JPH10325795A - Method and apparatus for measurement of medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate and measure the phase refractive index, the birefringence and the thickness of an object, to be measured, by using a light interference method. SOLUTION: Light from a light source 1 is condensed by a condensing lens 3. An object 4 to be measured is irradiated with the light. The object 4 to be measured or the condensing lens 3 and a reference-light mirror 6 are moved in such a way that intensities of interference light at the front and the rear of the reference-light mirror 6 and of the object 4 to be measured become respectively maximum. Then, the movement distance of the object 4 to be measured or the condensing lens 3 and that of the reference-light mirror 6 are found in a position in which the intensity of the interference light at the front becomes maximum and in a position in which the intensity of the interference light at the rear becomes maximum. Thereby, the refractive index and the thickness of the object 4 to be measured are measured simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for simultaneous measurement of refractive index and thickness of a medium, a simultaneous measurement apparatus, or a method or apparatus for measuring birefringence, or a method for simultaneous measurement of birefringence and thickness, or a simultaneous measurement apparatus or phase refraction. The present invention relates to a method for simultaneous measurement of refractive index and group refractive index, a measuring device, and an evaluation of a cured state or a degree of curing of a curable resin using the present measurement method.

[0002]

2. Description of the Related Art A method for non-contact measurement of optical characteristics such as the refractive index n (= phase refractive index np), birefringence, and thickness of a measurement object (medium) is one of the most basic techniques in the optical field. One. A representative example is an ellipsometer (automatic ellipsometer) [(1): Hiroshi Kubota et al. Polarization “Optical Handbook” 2,4 polarization analysis (pp. 256-26)
4), see Asakura Shoten]. This is a method of irradiating a medium (thin film) to be measured with light obliquely and focusing mainly on the difference in phase change between the P-polarized light and the S-polarized light of the reflected light. Is a method of measuring the refractive index n and the thickness t of the substrate and the thin film deposited on the surface of the substrate by observing the polarization state of the substrate.

Further, the film thickness and the refractive index of a medium are calculated using the reflectance.
n, there is also a reflectance analysis method for measuring the absorption coefficient.
Japanese Patent Application Laid-Open No. 75902/1988, Japanese Patent Application Laid-Open No. 63-128210, Japanese Patent Application Laid-Open No. 3-17505, and the like. JP-A-64-75902 and JP-A-63-12
The reflectivity analysis method disclosed in Japanese Patent No. 8210 measures the change in the reflected light intensity accompanying the change in the incident angle of the measurement light, that is, the incident angle dependence of the reflected light intensity, and determines the three extreme incident angles. This is a method of determining the characteristic value of the thin film using the method. JP-A-3-
The reflectance analysis method disclosed in Japanese Patent No. 17505 is a method of obtaining a characteristic value of a thin film from the incident angle dependence of the reflected light intensity obtained by detecting the light intensity on the rear side of the detection lens.

[0004] The equipment for performing these methods is of high precision and is frequently used for studying surfaces and thin films.
The apparatus itself is expensive, and the parallel beam irradiation part (about 1
The average refractive index n and thickness t in mm diameter) can only be measured. Furthermore, the thickness that can be actually measured is also
It was on the order of μm, and a thicker film could not be measured. In addition, there are a refractive index measurement of a medium by a prism, a refractive index n and a thickness t of a thin film by excitation of an optical waveguide mode, and the like, provided that the measurement surface is smooth. In contrast to the measurement method centered on such a thin film, in the optical field, the refractive index n of a medium including inorganic and organic materials is included.
There is a demand to accurately measure the thickness (including birefringence), the thickness t, and their spatial distribution.

[0005] In addition, the evaluation of the curing state or degree of curing of various curable resins (ultraviolet curing, heat curing, catalyst curing, electron beam curing, etc.) and coating films is currently carried out using gel fractions (measurement samples are measured using methyl ethyl ketone or the like as a solvent). The ratio of the weight change between the initial weight after extraction and the weight after solvent extraction) is the most common index. However, this evaluation method is a destructive test, and it takes a long time to prepare and evaluate a sample.

[0006]

In view of such a situation, here, based on an interference optical system using a low-coherence light source, the phase refractive index of a medium caused by irradiation of a converged beam is described.
A method for precisely measuring np and thickness t simultaneously, a method for precisely measuring the birefringence of a medium without the need for polarization control such as a polarizer / analyzer, a polarization rotator, and a phase refractive index
We propose a method for accurately and simultaneously measuring np and the group refractive index ng, and a method for evaluating the curability or degree of cure of a resin by using the method described above.

A Michelson interferometer with a low coherence light source has a coherence length of 2 along the light propagation axis.
Δlc (= ln (2) (2 / π) (λc2 / △ λ), where λc is the center wavelength of the light source, and Δλ is the resolution Δlc (〜) determined by the full width at half maximum (FWHM) of the spectrum of the light source.
(10 μm), the reflective surface can be identified, and it is used as a powerful diagnostic method in a minute area ((2): K.
Takada, I. Yokohama, K. Chida and J. Noda, "New m
easurement system for fault location in opticaL wa
veguide devices based on an interferometric techni
que, "AppLiedOptics, Vol.26, No. 9, pp.1603-1606 (1
987). (3): RC Youngquist, S. Carr and DE
N. Davies, "OpticaL coherence-domain reflectometry
: a newoptical evaluation technique, "Optics Let
ters, Vol. 12, No. 3, pp. 158-160 (1987). (4): H.
H. Gilgen, RP Novak, RP Salathe, W. Hodel an
dP. Beaud, "Submillimeter optical reflectometry,"
J. Lightwave Technology, Vol. 7, No. 8, pp.1225-1
233 (1989)).

Recently, the low coherence optical interferometry has been attracting attention in the field of biological photodiagnosis, and detection and visualization of subretinal tissue ((5): D. Huang, EA Swanson, CP L).
in, JS Schuman, WG Stinson, W. Chang, MR H
ee, T. Flotte, K. Gregory, CA Puliafito, JG
Fujimoto, "Optical coherency tomography," Scienc
e, Vol. 254, pp. 1178-1181, 22 Nov., 1991. (6):
JA Izatt, MR Hee, GM Owen, EA Swanson
and JG Fujimoto, "Optical coherence microscopy
in scattering media, "Optics Letters, Vol. 19, N
o. 8, pp. 590-592 (1994).) and measurement of eye length ((7)): AF Fercher, K. Mengedoht and W. Wre
ner, "Eye-length measurement by interferometry wit
h partially coherent light, "Optics Letters, Vol.
13, No. 3, pp. 186-188 (1988). (8): W. Drexier,
CK Hitzenberger, H. Sattmann AF Fercher, "Me
asurement of the thickness of fundus layers by par
tial coherence tomography, "Optical Engineering,
Vol. 34, No. 3, pp. 701-710 (1995).) And basic experiments for high-precision detection of subcutaneous tissue ((9): Shiraishi, Omi,
Haruna, Nishihara, "Basic experiment I for detecting in-vivo structure by low coherence light interference," The 56th JSAP Autumn Meeting 1995, 26a-SN-11 (1995)).

However, in the above-mentioned low coherence interferometry, the object to be measured (transparent plate) is irradiated with a parallel or condensed beam, and the optical path difference between the signal light reflected from the front and rear surfaces and the reference light becomes zero. The two positions of the reference light mirror are specified, and the optical path difference (group refractive index ng × thickness t) between the front surface and the rear surface of the measurement object is measured from these intervals. That is, in this case, since the measurement amount is only the group refractive index ng × the thickness t, separation measurement of the group refractive index ng or the phase refractive index np and the thickness t cannot be performed. Here, the group refractive index ng depends on the FWHM of the light source. As the FWHM increases, the influence of the wavelength dispersion of the refractive index of the object to be measured increases, and Δn (= ng−np) increases. Incidentally, the general refractive index n is a phase refractive index np
That is.

Phase index np (including birefringence), thickness of medium
Simultaneous optical measurement of t is an indispensable technology for manufacturers developing optical components and materials such as lenses. In particular, lenses require precise measurement of the thickness distribution simultaneously with the phase refractive index np. Recently, there are many optical components using polymers and liquid crystals in addition to various multi-component glasses, and simultaneous precision measurement of phase refractive index np (including birefringence) and thickness t is indispensable for the development of these components.・ It is a device. Also, research and development of various nonlinear optical materials are being actively pursued in order to realize a short wavelength light source and a wavelength tunable laser. However, when measuring the refractive index (including birefringence) of these new optical materials, simple phase Rate np, thickness t
Are required.

Also, in the medical field, for example, in the field of optical diagnosis and treatment, the phase refractive index np or group refractive index ng and thickness
The need for simultaneous measurement of t is increasing. For example, in ophthalmic treatment / diagnosis, precise measurement of the eye diameter, corneal thickness, and refractive index (accuracy is about 10 μm) is required. In this case, non-contact measurement is a condition, and an optical probe is used. However, at present, since it is impossible to separately measure the refractive index np or ng and the thickness t, the eye diameter, the thickness of the cornea, and the refractive index cannot be measured accurately. Furthermore, the optical CT, which is currently being actively studied,
(Construction of biological tomographic images using light) also requires the refractive index np or ng
And the thickness t must be measured simultaneously.

Further, in the quality evaluation and management of various protective layers (films) and coating films, evaluation using refractive index as an index is promising. This focuses on the fact that as various curable resins cure, the refractive index changes due to shrinkage and the like. In the case of measuring only the refractive index, it can be performed with a general Abbe refractometer, but in the Abbe refractometer, the measurement site of the refractive index in the measurement target is only the surface of the measurement target. In addition, it was impossible to measure the averaged refractive index of a measurement object having a non-uniform refractive index distribution in the thickness direction (the surface is cured, and the inside is uncured).
This is a serious problem when the cured state or degree of cure of the resin is evaluated using the refractive index as an index. In addition, it is necessary to prepare a test piece for the object to be measured according to the Abbe refractometer, and non-destructive and non-contact measurement was impossible.
Further, when the measurement target is an ultraviolet curable resin, the cured state changes depending on the thickness of the measurement target, and therefore, it is necessary to measure a term relating to the thickness of the measurement target.

The present invention has been made in view of the above circumstances, and has made it possible to separately measure the phase refractive index np and the birefringence and the thickness t of an object to be measured, and to simultaneously measure the phase refractive index np and the group refractive index ng. Provided is a method and an apparatus for measuring a medium using an optical interference method that enables the method, and a method for evaluating and measuring a cured state or a degree of curing of a curable resin by a refractive index using the method and the apparatus described above. The purpose is to:

[0014]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a driving means for holding and mounting an object to be measured or a condenser lens and a reference light mirror;
A light source, and a light receiving element that detects and detects light by multiplexing and interfering the reflected light from the measurement object and the reference light from the reference light mirror, from the light source of the interference optical system. The measurement object or the reference light mirror and the interference light intensity on the front and rear surfaces of the measurement object are respectively maximized, so that the measurement object or The condensing lens and the reference light mirror are moved, and the measurement object or the condensing lens and the reference light mirror are moved at a position where the maximum intensity of the interference light appears on the front surface and at a position where the maximum intensity of the interference light appears on the rear surface. A method for measuring a medium, comprising simultaneously measuring a refractive index and a thickness of the object to be measured by obtaining a distance, and a driving unit that holds and mounts the object to be measured and a reference light mirror. , A light source, a condensing lens held by holding means, and a light-receiving element for detecting by combining and interfering reflected light from the measurement object and reference light from the reference light mirror. The light from the light source of the interference optical system is condensed by the condensing lens and irradiates the object to be measured, and the interference light intensity on the front and rear surfaces of the reference light mirror and the object to be measured is The measurement object and the reference light mirror are moved so as to be maximum, respectively, and the measurement object and the reference light mirror at the position where the interference light maximum intensity appears on the front surface and the interference light maximum intensity position on the rear surface Measuring the refractive index and the thickness of the object to be measured simultaneously by calculating the moving distance of the medium.

Alternatively, driving means for holding and mounting a condenser lens and a reference light mirror, a light source, an object to be measured held by the holding means, light reflected from the object to be measured and reference from the reference light mirror A light receiving element for detecting light by multiplexing and interfering light, wherein the light from the light source of the interference optical system is condensed by the condensing lens on the object to be measured and the measurement is performed. By irradiating the object, the converging lens and the reference light mirror are moved so that the interference light intensity on the front surface and the rear surface of the reference light mirror and the front surface and the rear surface of the measurement object are maximized, and the interference light maximum intensity on the front surface The position where appears, and by determining the moving distance of the measurement object and the reference light mirror at the position of the interference light maximum intensity on the rear surface, it is possible to simultaneously measure the refractive index and thickness of the measurement object. It is a measurement method of a medium with symptoms.

Further, driving means for holding and mounting the object to be measured or the reference light mirror, a light source, and a light receiving means for detecting the reflected light from the object to be measured and the reference light from the reference light mirror by multiplexing / interfering with each other. An interference optical system comprising an element and
Light from the light source of the interference optical system is irradiated on the object to be measured, and two interference light intensities corresponding to an ordinary light and an extraordinary light at the front and rear surfaces of the reference light mirror and the object to be measured. Move the object to be measured or the reference light mirror so that each becomes the maximum, the position where the interference light maximum intensity appears on the front surface, and the two interference light maximum intensity corresponding to the ordinary ray and the extraordinary ray on the rear face. By measuring the moving distance of the measurement object or the reference light mirror at a position, a medium measuring method characterized by measuring the birefringence of the measurement object,
Driving means for holding and mounting the object to be measured, a light source, a reference light mirror held by the holding means, and detection by multiplexing / interfering reflected light from the object to be measured and reference light from the reference light mirror. An interference optical system comprising: a light receiving element that emits light from the light source of the interference optical system to the object to be measured; and a reference light mirror held by holding means and a front surface of the object to be measured. The object to be measured is moved so that the interference light intensity at the front and the two interference light intensities corresponding to the ordinary ray and the extraordinary ray at the rear surface are respectively maximized. A method of measuring a medium, comprising: measuring a birefringence of an object to be measured by calculating a difference in a moving distance between two positions of maximum intensity of interference light corresponding to a light beam and an extraordinary light beam.

Alternatively, a driving means for holding and mounting the reference light mirror, a light source, an object to be measured held by the holding means, a reflected light from the object to be measured and a reference light from the reference light mirror are multiplexed. An interference optical system including a light-receiving element that detects interference light, and irradiates the object to be measured with light from the light source of the interference optical system, and the reference light mirror and the front surface of the object to be measured. The reference light mirror is moved so that the interference light intensity at the front and the two interference light intensities corresponding to the ordinary ray and the extraordinary ray at the rear surface are respectively maximized. A method for measuring a medium, comprising: measuring a birefringence of an object to be measured by calculating a difference in a movement distance between two positions of maximum intensity of interference light corresponding to a light beam and an extraordinary light beam.

Further, a driving means for holding and mounting the object to be measured or the condensing lens and the reference light mirror, a light source, and multiplexing and interfering the reflected light from the object to be measured and the reference light from the reference light mirror. An interference optical system including a light receiving element for detecting the light, the light from the light source of the interference optical system is condensed by the condensing lens to irradiate the measurement object, the reference light mirror and the reference light mirror Move the measurement object or the condenser lens and the reference light mirror so that the interference light intensity on the front surface of the measurement object and the two interference light intensity corresponding to the ordinary ray and the extraordinary ray on the rear surface are respectively maximized. The object to be measured or the condensing lens and the reference lens at the position where the maximum intensity of the interference light appears on the front surface and at the position of the two maximum intensity of the interference light corresponding to the ordinary ray and the extraordinary ray on the rear face. A method for measuring a medium characterized by simultaneously measuring the birefringence and the thickness of the object to be measured by determining the moving distance of the optical mirror, and a driving unit that holds and mounts the object to be measured and a reference light mirror. , Light source,
A condensing lens, and an interference optical system including a light-receiving element for detecting by combining and interfering the reflected light from the object to be measured and the reference light from the reference light mirror, wherein the interference optical system includes: The light from the light source is condensed by the condensing lens and irradiated to the object to be measured. The object to be measured and the reference light mirror are moved so that the interference light intensities are maximized, and the position where the maximum intensity of the interference light appears on the front surface and the two interference light beams corresponding to the ordinary ray and the extraordinary ray on the rear face. A method for measuring a medium, wherein a birefringence and a thickness of the object to be measured are simultaneously measured by obtaining a difference between a moving distance of the object to be measured and a reference light mirror at a position of a maximum intensity.

Alternatively, driving means for holding and mounting the condenser lens and the reference light mirror, a light source, a measurement object held by the holding means, light reflected from the measurement object and reference from the reference light mirror. A light receiving element for detecting light by multiplexing and interfering light, wherein the light from the light source of the interference optical system is condensed by the condensing lens on the object to be measured and the measurement is performed. Irradiate the target object, so that the interference light intensity on the front surface of the reference light mirror and the measurement object and the two interference light intensity corresponding to the ordinary ray and the extraordinary ray on the rear face are respectively maximized, the condensing lens and By moving the reference light mirror, the measurement object and reference at the position where the maximum intensity of the interference light appears on the front surface and the position of the two maximum intensity of the interference light corresponding to the ordinary ray and the extraordinary ray on the rear face. By obtaining the difference between the moving distance of the optical mirror, a measuring method of the medium, characterized by simultaneously measuring the birefringence and thickness of the measurement object.

Further, driving means for holding and mounting the object to be measured or the condensing lens and the reference light mirror, a light source, and multiplexing / interfering the reflected light from the object to be measured and the reference light from the reference light mirror. An interference optical system including a light receiving element for detecting the light, the light from the light source of the interference optical system is condensed by the condensing lens to irradiate the measurement object, the reference light mirror and the reference light mirror The measurement object or the condenser lens and the reference light mirror are moved so that the interference light intensity on the front surface and the rear surface of the measurement object are respectively maximized, and the position where the interference light maximum intensity appears on the front surface and the rear surface By determining the moving distance of the object to be measured or the condensing lens and the reference light mirror at the position of the maximum intensity of the interference light in the phase refractive index and group refractive index of the object to be measured A measuring method of a medium characterized by performing time measurement, a driving means for holding and mounting a measurement object and a reference light mirror, a light source, a condenser lens held by holding means, An interference optical system including a light receiving element for detecting the reflected light by multiplexing and interfering the reference light from the reference light mirror, and collecting light from the light source of the interference optical system by the condenser lens. The measurement object and the reference light mirror are moved so that the interference light intensity at the front and rear surfaces of the reference light mirror and the measurement object is maximized, and the measurement object and the reference light mirror are moved. By calculating the moving distance of the object and the reference light mirror at the position where the maximum intensity of the interference light appears at the position of the maximum intensity of the interference light on the rear surface, the phase refractive index and the Measuring method of the medium, characterized by simultaneously measuring the beauty group index. Or
Driving means for holding and mounting the condenser lens and the reference light mirror, a light source, and an object to be measured held by the holding means,
An interference optical system including a light receiving element for detecting the reflected light from the measurement object by combining and interfering the reference light from the reference light mirror, wherein the light from the light source of the interference optical system is The condensing lens condenses the object to be measured and irradiates the object with the condensing lens so that the interference light intensity on the front and rear surfaces of the reference light mirror and the object to be measured is maximized. Move the lens and the reference light mirror, the position where the interference light maximum intensity appeared on the front surface,
Measurement of a medium characterized by simultaneously measuring a phase refractive index and a group refractive index of the measurement object by determining a movement distance of the measurement object and the reference light mirror at a position of the maximum intensity of the interference light on the rear surface. Is the way.

Also, a light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and another light splitting means for splitting the light by the means for splitting light. Means for irradiating the object to be measured with a condenser lens, driving means for holding and mounting the object to be measured or the condenser lens and the reference light mirror for minute movement, reflected light from the object to be measured and the reference A medium measuring device, wherein the refractive index and the thickness of the object to be measured are simultaneously measured by an interference optical system including a light receiving element that detects and multiplexes / interfers a reference light from an optical mirror. A light source, a unit for dividing light from the light source, a reference light mirror for receiving and reflecting one light divided by the unit for dividing light, and the other divided by the unit for dividing the light. Means for irradiating the object to be measured with a condensing lens, driving means for holding and mounting the object to be measured and the reference light mirror for minute movement, reflected light from the object to be measured and light from the reference light mirror. An apparatus for measuring a medium, wherein the refractive index and the thickness of the object to be measured are simultaneously measured by an interference optical system having a light receiving element for detecting and multiplexing and interfering a reference light.

Alternatively, a light source, a unit for dividing the light from the light source, a reference light mirror for receiving and reflecting one of the lights divided by the unit for dividing the light, and a second light divided by the unit for dividing the light Means for irradiating the object to be measured by a condensing lens, driving means for holding and mounting the condensing lens and the reference light mirror for fine movement, reflected light from the object to be measured, and reference light from the reference light mirror A measuring device for measuring the refractive index and the thickness of the object to be measured simultaneously by an interference optical system having a light receiving element for detecting by combining and interfering with each other.

Further, a light source, means for splitting the light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and another light splitting means for splitting the light split by the light splitting means Means for irradiating the object to be measured, driving means for holding and mounting the object to be measured or the reference light mirror for fine movement, and combining reflected light from the object to be measured and reference light from the reference light mirror A medium measuring device characterized by measuring the birefringence of the object to be measured by an interference optical system including a light receiving element for detecting by interference, a light source, and a unit for separating light from the light source; A reference light mirror that receives and reflects one light divided by the light dividing unit, a unit that irradiates the measurement target with the other light divided by the light dividing unit, and the measurement target The measurement object by the interference optical system, comprising: a driving unit that holds and mounts and moves the micro light, and a light receiving element that combines and interferes with the reflected light from the measurement object and the reference light from the reference light mirror to detect the light. A medium measuring device for measuring birefringence of an object.

Alternatively, a light source, a unit for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the unit for splitting light, and a second light split by the unit for splitting the light. Means for irradiating the object to be measured, driving means for holding and mounting the reference light mirror for minute movement, and detection by multiplexing / interfering the reflected light from the object to be measured and the reference light from the reference light mirror And a birefringence of the object to be measured by an interference optical system having a light receiving element.

Also, a light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and a second light splitting means for splitting the light split by the light splitting means. Means for irradiating the object to be measured with a condenser lens, driving means for holding and mounting the object to be measured or the condenser lens and the reference light mirror for minute movement, reflected light from the object to be measured and the reference A measuring apparatus for a medium, wherein the birefringence and the thickness of the object to be measured are simultaneously measured by an interference optical system including a light receiving element for detecting and multiplexing / interfering a reference light from an optical mirror. A light source, a unit for dividing light from the light source, a reference light mirror for receiving and reflecting one light divided by the unit for dividing light, and the other divided by the unit for dividing the light. Means for irradiating the object to be measured with a condensing lens, driving means for holding and mounting the object to be measured and the reference light mirror for minute movement, reflected light from the object to be measured and light from the reference light mirror. An apparatus for measuring a medium, wherein a birefringence and a thickness of an object to be measured are simultaneously measured by an interference optical system having a light receiving element for detecting and multiplexing / interfering a reference beam.

Alternatively, a light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and another light splitting means for splitting the light by the means for splitting light. Means for irradiating the object to be measured by a condensing lens, driving means for holding and mounting the condensing lens and the reference light mirror for fine movement, reflected light from the object to be measured, and reference light from the reference light mirror A medium measuring apparatus for simultaneously measuring the birefringence and the thickness of the object to be measured by an interference optical system including a light-receiving element for detecting the wavelength by multiplexing / interference.

Further, a light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and another light splitting means for splitting the light by the means for splitting light. Means for irradiating the object to be measured with a condenser lens, driving means for holding and mounting the object to be measured or the condenser lens and the reference light mirror for minute movement, reflected light from the object to be measured and the reference A medium measuring device for simultaneously measuring a phase refractive index and a group refractive index of the object to be measured by an interference optical system including a light receiving element for detecting and multiplexing / interfering a reference light from an optical mirror. A light source, a unit for dividing the light from the light source, a reference light mirror for receiving and reflecting one of the lights divided by the unit for dividing the light, and a unit for dividing the light. Means for irradiating the other object light to the object to be measured by a condenser lens, driving means for holding and mounting the object to be measured and the reference light mirror for minute movement, light reflected from the object to be measured and the reference A medium measuring device for simultaneously measuring a phase refractive index and a group refractive index of the object to be measured by an interference optical system including a light receiving element for detecting and multiplexing / interfering a reference light from an optical mirror. .

Alternatively, a light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and another light splitting means for splitting the light by the light splitting means Means for irradiating the object to be measured by a condensing lens, driving means for holding and mounting the condensing lens and the reference light mirror for fine movement, reflected light from the object to be measured, and reference light from the reference light mirror A medium measuring apparatus for simultaneously measuring the phase refractive index and the group refractive index of the object to be measured by an interference optical system including a light-receiving element that detects and multiplexes and interferes with each other.

In the simultaneous measurement of the refractive index and the birefringence and the thickness, the phase refractive index and the thickness of the object to be measured are derived simultaneously by using a calculation formula in consideration of the wavelength dispersion of the refractive index of the object to be measured. A method or apparatus for measuring a medium, characterized in that the light source is a light source that emits low coherence light. Further, the light source emitting the low coherence light is a linearly polarized light, non-polarized light or random polarized light source in the simultaneous measurement of the refractive index and the thickness and the simultaneous measurement of the phase refractive index and the group refractive index. And a device for measuring a medium, characterized in that the light source is a non-polarized or random polarized light source in the measurement of birefringence and the simultaneous measurement of birefringence and thickness.

Further, the light source for emitting the low coherence light has a coherence length Δlc (= ((ln (2)) × (2
/ Π) × (λc2 / △ λ)) / 2) is 30 μm or less, wherein the light source for emitting the low coherence light is:
A method or apparatus for measuring a medium, characterized in that the light is a light source obtained by dispersing light from a superluminescent diode or a white light source in a specific wavelength range using a monochromator.

The interference optical system is a method or apparatus for measuring a medium, comprising means for demultiplexing and combining light from the light source as one of the components. The driving means for holding and mounting the object, the reference light mirror, and the condenser lens is a fine movement stage or a medium measurement method or medium measurement apparatus.

The reference light mirror is fixed to a vibrator for oscillating the reference light mirror in order to phase-modulate the reference light in the interference optical system. In the measurement device, the phase modulation of the reference light is performed by changing the amplitude to λ of the oscillation center wavelength λc of the light source.
A medium measuring method or medium measuring apparatus characterized by applying a vibration of c / 2 or less and a frequency of 100 Hz or more.

Further, the light receiving element is a photodiode for heterodyne detection, wherein the detection signal is converted into a digital signal by a detection circuit and processed. A medium measuring method or a medium measuring device.

The object to be measured is a medium or a medium measuring device which is a medium which does not completely absorb light from the light source, and the object to be measured is a living tissue. Or a measuring device for a medium.

Further, a method for measuring a medium is characterized in that the cured state or the degree of cure of the curable resin is evaluated using an averaged refractive index as an index in the thickness direction of the curable resin, The refractive index measurement of the curable resin is performed by: a driving means for holding and mounting an object to be measured or a condensing lens and a reference light mirror; a light source; reflected light from the object to be measured and reference light from the reference light mirror. An interference optical system comprising a light-receiving element for detection by combining and interfering, and irradiates the object to be measured by condensing light from the light source of the interference optical system with the condenser lens, Move the object to be measured or the condensing lens and the reference light mirror so that the reference light mirror and the interference light intensity at the front and rear surfaces of the measurement object are respectively maximum, and obtain the maximum intensity of the interference light at the front surface. And it appeared position, by obtaining the measurement object or the moving distance of the condenser lens and the reference mirror at the position of the interference light maximum intensity at the rear face,
A method for measuring a medium, comprising simultaneously measuring a refractive index and a thickness of the object to be measured, the medium being held by a driving unit for holding and mounting the object to be measured and a reference light mirror, a light source, and a holding unit. A condensing lens, and an interference optical system including a light receiving element that detects the reflected light from the measurement object and the reference light from the reference light mirror by multiplexing and interfering,
The light from the light source of the interference optical system is condensed by the condenser lens and irradiates the object to be measured, and the interference light intensity on the front and rear surfaces of the reference light mirror and the object to be measured is maximized. As described above, the measurement object and the reference light mirror are moved, and the position where the interference light maximum intensity appears on the front surface and the movement distance of the measurement object and the reference light mirror at the position of the interference light maximum intensity on the rear surface are By obtaining, a method for measuring a medium characterized by simultaneously measuring the refractive index and the thickness of the object to be measured, or
Driving means for holding and mounting the condenser lens and the reference light mirror, a light source, and an object to be measured held by the holding means,
An interference optical system including a light receiving element for detecting the reflected light from the measurement object by combining and interfering the reference light from the reference light mirror, wherein the light from the light source of the interference optical system is The condensing lens condenses the object to be measured and irradiates the object with the condensing lens so that the interference light intensity on the front and rear surfaces of the reference light mirror and the object to be measured is maximized. Move the lens and the reference light mirror, the position where the interference light maximum intensity appeared on the front surface,
By measuring the moving distance of the object to be measured and the reference light mirror at the position of the maximum intensity of the interference light on the rear surface, by a method of measuring a medium characterized by simultaneously measuring the refractive index and thickness of the object to be measured A method for measuring a medium characterized by measuring, wherein the refractive index measurement of the curable resin is a light source, a unit for dividing light from the light source, and one of the lights divided by the unit for dividing the light. A reference light mirror that receives and reflects light, a unit that irradiates the other object light, which is divided by the unit that divides the light, to a measurement object with a condenser lens, and holds and mounts the measurement object or the condenser lens and the reference light mirror. Driving means for micro-moving
Simultaneously measure the refractive index and the thickness of the measurement object by an interference optical system including a light receiving element that combines and interferes with the reflected light from the measurement object and the reference light from the reference light mirror for detection. A medium measuring device, characterized in that:
A light source, a unit for dividing the light from the light source, a reference light mirror for receiving and reflecting one of the lights divided by the unit for dividing the light, and the other light divided by the unit for dividing the light measured by a condenser lens Means for irradiating the object;
A driving unit that holds and mounts the measurement object and the reference light mirror and performs minute movement, a light receiving element that detects reflected light from the measurement object and reference light from the reference light mirror by multiplexing / interfering with each other; A measuring device for a medium characterized by simultaneously measuring the refractive index and the thickness of the object to be measured by an interference optical system comprising: or a light source; a unit for separating light from the light source; and separating the light. A reference light mirror for receiving and reflecting one of the lights divided by the means, a means for irradiating the object to be measured with the other light divided by the means for dividing the light by a condenser lens, the condenser lens and the reference light mirror An interfering optical system comprising a driving means for holding and mounting and micro-moving, and a light receiving element for multiplexing / interfering the reflected light from the object to be measured and the reference light from the reference light mirror for detection. That by the measurement object medium of a measuring device and measuring simultaneously the refractive index and thickness of a measuring method of a medium and measuring.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides a driving means for holding and mounting an object to be measured or a condenser lens and a reference light mirror, a light source, and light reflected from the object to be measured. A light-receiving element for detecting and multiplexing / interfering the reference light from the reference light mirror, wherein light from the light source of the interference optical system is condensed by the condenser lens. The measurement object is irradiated, and the measurement object or the condenser lens and the reference light mirror are moved so that the interference light intensity on the front and rear surfaces of the reference light mirror and the measurement object is maximized. By measuring the position where the maximum intensity of the interference light appears on the front surface and the moving distance of the measuring object or the condensing lens and the reference light mirror at the position of the maximum intensity of the interference light on the rear surface, the measurement is performed. This is a method for measuring a medium characterized by simultaneously measuring the refractive index and the thickness of an elephant, and has the effect of separating and simultaneously measuring the refractive index and the thickness of the object without contact. .

According to a second aspect of the present invention, there is provided a driving means for holding and mounting an object to be measured and a reference light mirror, a light source, a condenser lens held by the holding means, An interference optical system including a light receiving element for detecting the reflected light by combining and interfering the reflected light and the reference light from the reference light mirror, wherein light from the light source of the interference optical system is collected by the condenser lens. Irradiate the measurement object with light,
The measurement object and the reference light mirror are moved so that the interference light intensity on the front and rear surfaces of the reference light mirror and the measurement object are respectively maximized, and a position where the interference light maximum intensity appears on the front surface, By measuring the moving distance of the measurement object and the reference light mirror at the position of the maximum intensity of the interference light on the rear surface, a measurement method of a medium characterized by simultaneously measuring the refractive index and thickness of the measurement object. By scanning the object to be measured and the reference light mirror, it is possible to perform non-contact separation and simultaneous measurement of the refractive index and thickness of the object to be measured.

According to a third aspect of the present invention, there is provided a driving means for holding and mounting a condenser lens and a reference light mirror, a light source, an object to be measured held by the holding means, and An interference optical system comprising a light receiving element for detecting the reflected light by multiplexing and interfering the reference light from the reference light mirror, wherein the light from the light source of the interference optical system is applied to the object to be measured. The condensing lens and the reference light mirror are condensed by a condensing lens and illuminated on the object to be measured, so that the interference light intensity on the front and rear surfaces of the reference light mirror and the object to be measured is maximized, respectively. Is moved, the position where the interference light maximum intensity appears on the front surface, and the moving distance of the measurement object and the reference light mirror at the position of the interference light maximum intensity on the rear surface are determined. Is a method of measuring a medium characterized by simultaneous measurement of the refractive index of the object to be measured in a non-contact manner by scanning the condenser lens and the reference light mirror while the object to be measured is fixed. And the thickness can be separated and measured simultaneously.

According to a fourth aspect of the present invention, there is provided a driving means for holding and mounting an object to be measured or a reference light mirror, a light source, light reflected from the object to be measured and reference light from the reference light mirror. A light receiving element for multiplexing and interfering with the light, and irradiating the object to be measured with light from the light source of the interference optical system, the reference light mirror and the object to be measured The measurement object or the reference light mirror is moved so that the two interference light intensities corresponding to the ordinary light beam and the extraordinary light beam on the front surface and the ordinary light beam and the extraordinary light beam on the rear surface are respectively maximized. Appearing position, by determining the moving distance of the measurement object or the reference light mirror at the position of the two interference light maximum intensity corresponding to the ordinary ray and the extraordinary ray on the rear surface, the measurement object It is obtained by the measurement method of the medium and measuring the birefringence, an effect that a very simple structure, the birefringence in a non-contact can be measured.

According to a fifth aspect of the present invention, there is provided a driving means for holding and mounting an object to be measured, a light source, a reference light mirror held by the holding means, a light reflected from the object to be measured, and A light receiving element for multiplexing and interfering the reference light from the reference light mirror to detect the light, and irradiates the object to be measured with light from the light source of the interference optical system and holds the light. Move the measurement object so that the two interference light intensities corresponding to the reference light mirror and the interference light intensity on the front surface of the measurement object and the ordinary ray and the extraordinary ray on the rear surface held by the means are respectively maximized, The birefringence of the measurement object is measured by determining the difference between the position where the maximum intensity of the interference light on the front surface appears and the position of the maximum intensity of the interference light corresponding to the ordinary ray and the extraordinary ray on the rear face. It is obtained by the measurement method of the medium, characterized in, such an action can be measured easily birefringence by scanning only the measurement object.

According to a sixth aspect of the present invention, there is provided a driving means for holding and mounting a reference light mirror, a light source, an object to be measured held by the holding means, light reflected from the object to be measured, and A light receiving element for detecting by multiplexing and interfering reference light from a reference light mirror, and irradiating the object to be measured with light from the light source of the interference optical system, The reference light mirror and the interference light intensity on the front surface of the object to be measured and the reference light mirror are moved so that the two interference light intensity corresponding to the ordinary ray and the extraordinary ray on the rear face become maximum, respectively. By measuring the difference in the distance between the position where the intensity appears and the position of the two interference light maximum intensities corresponding to the ordinary ray and the extraordinary ray on the rear surface, the birefringence of the measurement object is measured. Is obtained by a method of measuring quality, while fixing the object to be measured, conveniently birefringence only by scanning the reference mirror has an effect that can be measured.

According to a seventh aspect of the present invention, there is provided a driving means for holding and mounting an object to be measured or a condenser lens and a reference light mirror, a light source, light reflected from the object to be measured and the reference light mirror. And a light-receiving element for detecting a reference light by multiplexing / interfering the light from the light source, the light from the light source of the interference optical system being condensed by the condenser lens, and Irradiating the object to be measured or the collection so that the interference light intensity on the front surface of the reference light mirror and the object to be measured and the two interference light intensities corresponding to the ordinary ray and the extraordinary ray on the rear surface are maximized. By moving the optical lens and the reference light mirror, the object to be measured is located at the position where the maximum intensity of the interference light appears on the front surface and at the position of the two maximum intensity of the interference light corresponding to the ordinary and extraordinary rays on the rear surface. Is a method of measuring a medium characterized by simultaneously measuring the birefringence and the thickness of the object to be measured by obtaining the moving distance of the condensing lens and the reference light mirror. Birefringence and thickness can be separated and measured simultaneously without contact.

According to an eighth aspect of the present invention, there is provided a driving means for holding and mounting an object to be measured and a reference light mirror, a light source, a condenser lens, light reflected from the object to be measured and the reference light. A light receiving element for multiplexing / interfering a reference light from a mirror to detect the light, wherein light from the light source of the interference optical system is condensed by the condensing lens and the measurement object Irradiate the object, so that the interference light intensity on the front surface of the reference light mirror and the measurement object and the two interference light intensity corresponding to the ordinary ray and the extraordinary ray on the rear surface are respectively maximum, the measurement object and the The reference light mirror is moved, and the object to be measured and the reference light mirror are moved at the position where the maximum intensity of the interference light appears on the front surface and at the position of the two maximum intensity of the interference light corresponding to the ordinary ray and the extraordinary ray on the rear face. By determining the difference in separation, it is a method of measuring a medium characterized by simultaneously measuring the birefringence and the thickness of the measurement object, by simply scanning the measurement object and the reference light mirror, This has the effect that the birefringence and thickness of the object to be measured can be easily separated and measured simultaneously without contact.

According to a ninth aspect of the present invention, there is provided a driving unit for holding and mounting a condenser lens and a reference light mirror, a light source, an object to be measured held by the holding unit, An interference optical system including a reflected light and a light receiving element that detects and detects the combined light by combining and interfering the reference light from the reference light mirror, wherein the light from the light source of the interference optical system is applied to the object to be measured. The light is condensed by a condenser lens and irradiates the object to be measured. So that the converging lens and the reference light mirror are moved, and a position where the maximum intensity of the interference light appears on the front surface;
The birefringence and thickness of the measurement object are simultaneously determined by determining the difference between the moving distance of the measurement object and the reference light mirror at the position of the two interference light maximum intensities corresponding to the ordinary ray and the extraordinary ray on the rear surface. It is a method of measuring a medium characterized by measuring, with the measurement object fixed,
By simply scanning the condenser lens and the reference light mirror, the birefringence and thickness of the object to be measured can be separated and measured simultaneously without contact.

According to a tenth aspect of the present invention, there is provided a driving means for holding and mounting an object to be measured or a condenser lens and a reference light mirror, a light source, light reflected from the object to be measured and the reference light mirror. And a light-receiving element for detecting by combining and interfering the reference light from the light source, wherein the light from the light source of the interference optical system is condensed by the condensing lens and the object to be measured is collected. And moving the object to be measured or the condensing lens and the reference light mirror so that the interference light intensity at the front and rear surfaces of the reference light mirror and the object to be measured are maximized. The position at which the light maximum intensity appears and the movement distance of the measurement object or the condensing lens and the reference light mirror at the position of the interference light maximum intensity on the rear surface determine the measurement object. It is a method for measuring a medium characterized by simultaneously measuring the phase refractive index and the group refractive index, and it is possible to simultaneously measure the phase refractive index and the group refractive index of a measurement target having a known thickness in a non-contact manner. Has an action.

According to an eleventh aspect of the present invention, there is provided a driving means for holding and mounting an object to be measured and a reference light mirror,
A light source, a condenser lens held by holding means, and an interference optical system including a light receiving element that multiplexes and interferes with reflected light from the measurement object and reference light from the reference light mirror to detect the light. The light from the light source of the interference optical system is condensed by the condenser lens and irradiates the object to be measured, and the interference light intensities at the front and rear surfaces of the reference light mirror and the object to be measured are respectively The measurement object and the reference light mirror are moved so that the maximum, the position where the interference light maximum intensity appears on the front surface, and the measurement object and the reference light mirror at the position of the interference light maximum intensity on the rear surface By determining the moving distance, a method for measuring a medium characterized by simultaneously measuring the phase refractive index and the group refractive index of the measurement object, the measurement object and the reference light mirror By 査, it has the effect of thickness of the non-contact can simultaneously measure the phase index and the group index of the known measurement object.

According to a twelfth aspect of the present invention, there is provided a driving means for holding and mounting a condenser lens and a reference light mirror,
A light source, an object to be measured held by holding means, and an interference optical system including a light receiving element for detecting by combining and interfering reflected light from the object to be measured and reference light from the reference light mirror. There, the light from the light source of the interference optical system is condensed by the condensing lens on the measurement object and irradiates the measurement object, the front and rear surfaces of the reference light mirror and the measurement object The condensing lens and the reference light mirror are moved so that the interference light intensity is maximized, and the measurement object at the position where the interference light maximum intensity appears on the front surface and the interference light maximum intensity position on the rear surface And by determining the moving distance of the reference light mirror, a method for measuring a medium characterized by simultaneously measuring the phase refractive index and the group refractive index of the object to be measured, wherein the object to be measured is fixed. Also, an effect that by scanning the reference mirror and the condenser lens, the thickness of the non-contact can simultaneously measure the phase index and the group index of the known measurement object.

According to a thirteenth aspect of the present invention, there is provided a light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one of the lights split by the light splitting means, and Means for irradiating the object to be measured with a condensing lens with the other light divided by the means for dividing, a driving means for holding and mounting the object to be measured or the condensing lens and the reference light mirror and performing a minute movement, Simultaneously measuring the refractive index and the thickness of the measurement object by an interference optical system including a light receiving element that combines and interferes with the reflected light from the measurement object and the reference light from the reference light mirror for detection. It is a medium measuring device characterized by the fact that a simple interference optical system simply adds a driving means for holding and mounting a measuring object or a condensing lens and a reference light mirror and performing a minute movement. It has an effect of simultaneously measuring device can be of refractive index and thickness of the measuring object.

According to a fourteenth aspect of the present invention, there is provided a light source, a means for dividing light from the light source, a reference light mirror for receiving and reflecting one of the lights divided by the light dividing means, and Means for irradiating the other light separated by the means for separating the object to be measured with a condenser lens, driving means for holding and mounting the measurement object and the reference light mirror for minute movement, and A medium for simultaneously measuring the refractive index and the thickness of the object to be measured by an interference optical system including a light receiving element for detecting the reflected light by multiplexing / interfering the reflected light and the reference light from the reference light mirror; Simultaneous measurement of the refractive index and thickness of the measurement object by simply adding a driving means for holding and mounting the object to be measured and the reference light mirror and moving it minutely to a simple interference optical system. It has the effect that it is location.

According to a fifteenth aspect of the present invention, there is provided a light source, means for dividing light from the light source, a reference light mirror for receiving and reflecting one of the lights divided by the light dividing means, and Means for irradiating the object to be measured with a condensing lens with the other light divided by the means for dividing the light, driving means for holding and mounting the condensing lens and the reference light mirror for minute movement, and reflection from the object to be measured A medium characterized by simultaneously measuring the refractive index and the thickness of the object to be measured by an interference optical system including a light receiving element for multiplexing / interfering the light and the reference light from the reference light mirror for detection. It is a measurement device, and simply adds a driving means for holding and mounting a condenser lens and a reference light mirror on a simple interference optical system and moving it finely. It has an effect of simultaneously measuring device can be of refractive index and thickness.

According to a sixteenth aspect of the present invention, there is provided a light source, means for dividing light from the light source, a reference light mirror for receiving and reflecting one of the lights divided by the light dividing means, and Means for irradiating the object to be measured with the other light divided by the means for dividing, the driving means for holding and mounting the object to be measured or the reference light mirror and moving it slightly, and the reflected light from the object to be measured and A medium detecting device for measuring the birefringence of the object to be measured by an interference optical system including a light receiving element for multiplexing / interfering the reference light from the reference light mirror and detecting the combined light. The birefringence measuring device for the object to be measured can be obtained simply by adding a driving means for holding and mounting the object to be measured or the reference light mirror to the simple interference optical system and moving the object minutely.

According to a seventeenth aspect of the present invention, there is provided a light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one of the lights split by the light splitting means, and Means for irradiating the object to be measured with the other light divided by the means for dividing, a driving means for holding and mounting the object to be measured and for micro-moving, reflected light from the object to be measured and light from the reference light mirror. A medium measuring device for measuring the birefringence of the object to be measured by an interference optical system having a light receiving element for detecting and multiplexing / interfering the reference light; By simply adding a driving means for holding and mounting the object to be measured and moving it in the system, the birefringence measuring device for the object to be measured can be provided.

According to an eighteenth aspect of the present invention, there is provided a light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one of the lights split by the light splitting means, and Means for irradiating the object to be measured with the other light divided by the means for dividing, a driving means for holding and mounting the reference light mirror for minute movement, reflected light from the object to be measured and light from the reference light mirror Combines reference light
A medium measuring device characterized by measuring the birefringence of the object to be measured by an interference optical system having a light receiving element that detects and detects interference, a reference light mirror to a simple interference optical system By simply adding a driving means for holding and mounting and moving it minutely, the birefringence measuring device for the object to be measured can be provided while the object to be measured is fixed.

According to a nineteenth aspect of the present invention, there is provided a light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one of the lights split by the light splitting means, and Means for irradiating the object to be measured with a condensing lens with the other light divided by the means for dividing, a driving means for holding and mounting the object to be measured or the condensing lens and the reference light mirror and performing a minute movement, Simultaneously measuring the birefringence and the thickness of the object to be measured by an interference optical system including a light receiving element that combines and interferes with the reflected light from the object to be measured and the reference light from the reference light mirror for detection. It is a medium measuring device characterized by the fact that a simple interference optical system only needs to add a driving means for holding and mounting a measuring object or a condensing lens and a reference light mirror and performing a minute movement. It has an effect that it is simultaneous analysis device of the birefringence and thickness of the measuring object.

According to a twentieth aspect of the present invention, a light source, means for dividing light from the light source, a reference light mirror for receiving and reflecting one of the lights divided by the light dividing means, Means for irradiating the other light separated by the means for separating the object to be measured with a condenser lens, driving means for holding and mounting the measurement object and the reference light mirror for minute movement, and A medium for simultaneously measuring the birefringence and the thickness of the object to be measured by an interference optical system including a light receiving element for detecting the reflected light by combining and interfering the reflected light and the reference light from the reference light mirror. Simultaneous measurement of the birefringence and thickness of the measurement object by simply adding a driving means for holding and mounting the measurement object and the reference light mirror and moving it minutely to a simple interference optical system. It has the effect that it is location.

According to a twenty-first aspect of the present invention, there is provided a light source, a means for dividing light from the light source, a reference light mirror for receiving and reflecting one of the lights divided by the light dividing means, Means for irradiating the object to be measured with a condensing lens with the other light divided by the means for dividing the light, driving means for holding and mounting the condensing lens and the reference light mirror for minute movement, and reflection from the object to be measured A medium characterized in that the birefringence and the thickness of the object to be measured are simultaneously measured by an interference optical system including a light receiving element for multiplexing / interfering the light and the reference light from the reference light mirror for detection. It is a measurement device, and simply adds a driving means for holding and mounting a condenser lens and a reference light mirror on a simple interference optical system and moving it finely. It has an effect that it is simultaneous analysis device of the birefringence and thickness.

According to a twenty-second aspect of the present invention, there is provided a light source, means for dividing light from the light source, a reference light mirror for receiving and reflecting one of the lights divided by the light dividing means, and Means for irradiating the object to be measured with a condensing lens with the other light divided by the means for dividing, a driving means for holding and mounting the object to be measured or the condensing lens and the reference light mirror and performing a minute movement, Simultaneously measure the phase refractive index and the group refractive index of the measurement object by an interference optical system including a light receiving element that combines and interferes with the reflected light from the measurement object and the reference light from the reference light mirror for detection. It is a device for measuring a medium characterized by the fact that a simple interference optical system holds and mounts an object to be measured or a condensing lens and a reference light mirror, and has a driving means for minute movement. Simply, it has the effect of thickness can simultaneously measuring device phase index and the group index of a known measurement object.

According to a twenty-third aspect of the present invention, there is provided a light source, means for dividing light from the light source, a reference light mirror for receiving and reflecting one of the lights divided by the light dividing means, and Means for irradiating the other light separated by the means for separating the object to be measured with a condenser lens, driving means for holding and mounting the measurement object and the reference light mirror for minute movement, and Simultaneously measuring a phase refractive index and a group refractive index of the object to be measured by an interference optical system including a light receiving element for detecting and detecting the reflected light by multiplexing and interfering the reflected light and the reference light from the reference light mirror. It is a measuring device for a medium to be measured, and a measuring object with a known thickness can be obtained by simply adding a driving means for holding and mounting a measuring object and a reference light mirror and moving it slightly to a simple interference optical system. It has an effect that it is simultaneous measurement apparatus phase index and group index.

According to a twenty-fourth aspect of the present invention, there is provided a light source, means for dividing light from the light source, a reference light mirror for receiving and reflecting one of the lights divided by the light dividing means, and Means for irradiating the object to be measured with a condensing lens with the other light divided by the means for dividing the light, driving means for holding and mounting the condensing lens and the reference light mirror for minute movement, and reflection from the object to be measured A phase refraction index and a group refraction index of the object to be measured are simultaneously measured by an interference optical system including a light receiving element for multiplexing / interfering the light and the reference light from the reference light mirror for detection. It is a measurement device for the medium, and simply adds a driving means for holding and mounting the condenser lens and the reference light mirror on the simple interference optical system and moving it minutely, leaving the measurement object fixed. Thickness has the effect that it is simultaneous measurement apparatus phase index and the group index of a known measurement object.

According to a twenty-fifth aspect of the present invention, in the simultaneous measurement of the refractive index and the thickness, the phase of the object to be measured is calculated by using a calculation formula in consideration of the wavelength dispersion of the refractive index of the object to be measured. The method for measuring a medium according to any one of claims 1 to 3, wherein the refractive index and the thickness are derived at the same time, and the phase refractive index and the thickness of the object to be measured are simultaneously derived with high accuracy. Has the effect of being able to.

According to a twenty-sixth aspect of the present invention, the simultaneous measurement of the birefringence and the thickness is performed by using a calculation formula in consideration of the wavelength dispersion of the refractive index of the object to be measured. The method for measuring a medium according to any one of claims 7 to 9, wherein the refractive index and the thickness are derived at the same time, and the birefringence and the thickness of the object to be measured can be derived at the same time with high accuracy. It has the action of:

According to a twenty-seventh aspect of the present invention, the light source is a light source that emits low coherence light.
This is a method for measuring a medium described in the description, and has an effect that a reflection surface from a measurement object can be identified with high accuracy.

According to a twenty-eighth aspect of the present invention, in the method for measuring a medium according to any one of the fourth to ninth aspects, the light source is a light source that emits low coherence light. This has the effect that the reflection surface from the measurement object can be identified with high accuracy.

According to a twenty-ninth aspect of the present invention, in the method for measuring a medium according to the twenty-seventh aspect, the light source for emitting the low coherence light is a linearly polarized light, a non-polarized light, or a randomly polarized light source. This has the effect that the refractive index and the thickness can be measured simultaneously without being influenced by the polarization state of the light source.

The invention according to claim 30 of the present invention is the method according to claim 28, wherein the light source for emitting the low coherence light is a non-polarized or random polarized light source. This has the effect that birefringence measurement and simultaneous measurement of birefringence and thickness can be performed without controlling the polarization of the light source.

According to a thirty-first aspect of the present invention, the light source for emitting the low coherence light has a coherence distance Δlc
(= ((Ln (2)) × (2 / π) × (λc ² / △
31) The method for measuring a medium according to claim 29, wherein λ)) / 2) is 30 μm or less, and the reflection surface from the object to be measured is 30 μm or less with high accuracy. It has the effect of being able to be identified.

According to a thirty-second aspect of the present invention, there is provided the method for measuring a medium according to the thirty-first aspect, wherein the light source emitting the low coherence light is a superluminescence diode. This has the effect that the low coherence interference optical system can be configured easily and inexpensively.

According to a thirty-third aspect of the present invention, the light source for emitting the low coherence light is a light source obtained by dispersing light from a white light source into a specific wavelength range using a monochromator. 31 is a method for measuring a medium described in 31. The method has a function of easily performing measurement at a specific desired wavelength and measuring wavelength characteristics (wavelength dispersion).

According to a thirty-fourth aspect of the present invention, the interference optical system includes means for demultiplexing and combining light from the light source as one of the components.
12. The method for measuring a medium according to any one of Items 1 to 12, having an effect that the propagation of the light beam can be determined at a desired position.

According to a thirty-fifth aspect of the present invention, the driving means for holding and mounting the object to be measured, the reference light mirror and the condenser lens is a fine movement stage. 12. The method for measuring a medium according to any one of the above 12, which has an effect that a highly accurate driving means can be easily obtained.

According to a thirty-sixth aspect of the present invention, the reference light mirror is fixed to a vibrator for vibrating the reference light mirror in order to phase-modulate the reference light in the interference optical system. The method for measuring a medium according to any one of claims 1 to 12, wherein the processing of the interference light signal is stabilized, and the front and back surfaces can be positioned with high accuracy.

According to a thirty-seventh aspect of the present invention, in the phase modulation of the reference light, a vibration having an amplitude of not more than λc / 2 of the oscillation center wavelength λc of the light source and a frequency of not less than 100 Hz is applied. The method for measuring a medium according to claim 36 has the effect of stabilizing an interference light signal and increasing the speed of signal processing.

The invention according to claim 38 of the present invention is the method according to any one of claims 1 to 12, wherein the light receiving element is a photodiode for heterodyne detection. This has the effect that stable processing of the interference light signal can be performed.

The medium according to any one of claims 1 to 12, wherein the heterodyne-detected detection signal is converted into a digital signal by a detection circuit and processed. And has the effect that the detection signal can be processed simply and at high speed.

The invention according to claim 40 of the present invention is characterized in that the object to be measured is a medium that does not completely absorb light from the light source. The method has the function of detecting reflected light (signal light) from the object to be measured.

The invention according to claim 41 of the present invention is the method according to any one of claims 1 to 12, wherein the object to be measured is a living tissue. It has the effect that measurement can be performed without damaging the living tissue.

According to an embodiment of the present invention, in the simultaneous measurement of the refractive index and the thickness, the phase of the object to be measured is calculated by using a calculation formula in consideration of the wavelength dispersion of the refractive index of the object to be measured. 16. The apparatus for measuring a medium according to claim 13, wherein the refractive index and the thickness are derived simultaneously, and the phase refractive index and the thickness of the object to be measured are measured with high accuracy. It has an effect that a device can be manufactured.

In the invention according to claim 43 of the present invention, the simultaneous measurement of the birefringence and the thickness is performed by using a calculation formula in consideration of the wavelength dispersion of the refractive index of the object to be measured. 22. The apparatus for measuring a medium according to claim 19, wherein the refractive index and the thickness are derived at the same time, and the apparatus for simultaneously measuring the birefringence and the thickness of a measurement object with high accuracy. Can be produced.

The invention according to claim 44 of the present invention, wherein the light source is a light source that emits low coherence light, wherein the measurement of the medium according to any one of claims 13 to 15 or 22 to 24 is performed. The device has the function of accurately identifying the reflection surface from the object to be measured and producing a high-performance device.

The invention according to claim 45 of the present invention is the medium measuring device according to any one of claims 16 to 21, wherein the light source is a light source that emits low coherence light. This has the effect that the reflection surface from the measurement object can be identified with high accuracy, and a high-performance device can be manufactured.

The invention according to claim 46, wherein the light source for emitting the low coherence light is a linearly polarized light, non-polarized light or random polarized light source. The reflective surface from the object to be measured can be accurately identified without being influenced by the polarization state of the light source, and an effect is obtained that a high-performance simultaneous refractive index and thickness measuring device can be manufactured.

The invention according to claim 47 of the present invention is the medium measuring apparatus according to claim 45, wherein the light source for emitting the low coherence light is an unpolarized or random polarized light source. Therefore, it is possible to accurately identify the reflection surface from the measurement object without controlling the polarization of the light source, and to produce a high-performance birefringence measurement and a simultaneous birefringence and thickness measurement apparatus.

According to a forty-eighth aspect of the present invention, the light source for emitting the low coherence light has a coherence length Δlc
(= ((Ln (2)) × (2 / π) × (λc ² / △
48) The apparatus for measuring a medium according to any one of claims 46 and 47, wherein λ)) / 2) is 30 µm or less, wherein a reflection surface from a measurement object can be identified with 30 µm or less; This has the effect that a high-resolution device can be provided.

According to a fifty-ninth aspect of the present invention, the light source for emitting the low coherence light is a superluminescent diode. There is an effect that a high-performance light source can be incorporated at low cost.

According to a fiftyth aspect of the present invention, the light source for emitting the low coherence light is a light source obtained by dispersing light from a white light source to a specific wavelength by a monochromator. It is a device for measuring the medium described, and can be easily measured at a specific desired wavelength,
In addition, it has an effect that an apparatus capable of measuring wavelength characteristics (wavelength dispersion) can be easily formed.

According to a fifty-first aspect of the present invention, the interference optical system includes means for demultiplexing and combining light from the light source as one of the components.
According to a third aspect of the present invention, there is provided an apparatus for measuring a medium according to any one of the items 3 to 24, which has an effect that light beam propagation in the apparatus can be easily determined at a desired position.

According to a fifty-second aspect of the present invention, the driving means for holding and mounting the object to be measured, the reference light mirror and the condenser lens is a fine movement stage. 24. An apparatus for measuring a medium according to any one of the items 24, which has an effect that a highly accurate driving means can be easily obtained.

According to a fifty-third aspect of the present invention, the reference light mirror is fixed to a vibrator that vibrates the reference light mirror in order to phase-modulate the reference light in the interference optical system. An apparatus for measuring a medium according to any one of claims 13 to 24, which stabilizes processing of an interference light signal and has an effect of enabling accurate measurement.

According to a fifty-fourth aspect of the present invention, the phase modulation of the reference light is performed by applying a vibration whose amplitude is not more than λc / 2 of the oscillation center wavelength λc of the light source and whose frequency is not less than 100 Hz. A medium measuring device according to claim 53, which has an effect of stabilizing an interference light signal and speeding up signal processing.

The invention according to claim 55 of the present invention is the apparatus for measuring a medium according to any one of claims 13 to 24, wherein said light receiving element is a photodiode for heterodyne detection. This has the effect that stable processing of the interference light signal can be performed.

The medium according to any one of claims 13 to 24, wherein the detection signal subjected to the heterodyne detection is converted into a digital signal by a detection circuit and processed. And has the effect that the detection signal can be processed simply and at high speed.

According to a fifty-seventh aspect of the present invention, the object to be measured is a medium that does not completely absorb light from the light source.
This is an apparatus for measuring a medium according to the description, and has an operation of detecting reflected light (signal light) of an object to be measured.

According to a fifty-eighth aspect of the present invention, there is provided the medium measuring device according to any one of the thirteenth to twenty-fourth aspects, wherein the object to be measured is a living tissue. It has the effect that highly accurate measurement can be performed without damaging the living tissue.

According to a fifty-ninth aspect of the present invention, the evaluation of the cured state or the degree of cure of the curable resin in the thickness direction of the curable resin using the averaged refractive index as an index. This is a method for measuring a characteristic medium, and has an effect that the cured state or the degree of cure of the resin can be measured by the refractive index.

According to a 60th aspect of the present invention, in the method for measuring a medium, the refractive index of the curable resin is measured by the measuring method according to any one of the first to third aspects. This has the effect that the refractive index and thickness of the resin can be measured with high accuracy.

According to a sixteenth aspect of the present invention, in the method for measuring a medium, the refractive index of the curable resin is measured by the measuring device according to any one of the thirteenth to fifteenth aspects. This has the effect that the refractive index and thickness of the resin can be measured with high accuracy.

The low coherence light source is not limited to a superluminescent diode or a white light source, and any light source having a coherence distance of 30 μm or less, such as a laser diode driven by an injection current of a threshold value or less, is used. Can be used. Therefore, in this measurement method and measurement apparatus, by using several laser diodes having different oscillation center wavelengths in combination, the refractive index of the object to be measured can be measured in the same manner as in the case of using a white light source obtained by dispersing a white light source with a monochromator. Chromatic dispersion can also be measured. The components of the interference optical system may be any components that can split the light from the light source and combine and interfere the signal light and the reference light, and a beam splitter, a half mirror, a single mode fiber coupler, or the like can be used. . The driving means is not limited to the fine movement stage, but may be any as long as it can accurately measure the moving distance. Also, the vibrator may be a piezoelectric actuator, an electromagnetic actuator, or the like, as long as stable vibration and amplitude can be obtained.

The principle of simultaneous measurement of the phase refractive index np or the birefringence and the thickness t of the object to be measured, the birefringence measurement, the principle of simultaneous measurement of the phase refractive index and the group refractive index, and the cured state or degree of cure of the curable resin The evaluation based on the refractive index will be described.

FIG. 1 is a basic system configuration diagram of simultaneous measurement of phase refractive index and thickness, and simultaneous measurement of phase refractive index and group refractive index according to one embodiment of the present invention. Here, first, the light path in the present system configuration will be described. The light emitted from the light source 1 is collimated by a lens 12a, and is split / combined by a demultiplexing / combining means 2 for demultiplexing / combining the light from the light source 1.
It is led to. The light source 1 is bisected by the demultiplexing / multiplexing means 2,
One of the lights goes straight and is condensed on the measurement object 4 held and mounted on the driving means 5 by the condenser lens 3 held and mounted on the driving means 8. On the other hand, the other light travels in the vertical direction from the demultiplexing / combining means 2 and is held and mounted on the driving means 7.
The light is emitted to the reference light mirror 6 fixed to the vibrator 9. Vibration at a frequency f and a predetermined amplitude is applied to the vibrator 9,
The reflected light (reference light) from the reference light mirror 6 is phase-modulated. The reflected light (signal light) from the measurement object 4 is incident on the light receiving element 10 via the condenser lens 3, the demultiplexing / combining means 2, and the lens 12b. The reflected light (reference light) from the reference light mirror 6 is incident on the light receiving element 10 via the demultiplexing / combining means 2 and the lens 12b. The detection signal of the light receiving element 10 is converted into a digital signal by the detection circuit 11,
The data is processed by the PC 13. The driving means 5, 7, 8 are controlled by a signal from the PC 13 via the stage controller 14.

1) As a method of simultaneously measuring the phase refractive index np or the birefringence and the thickness t of the object to be measured and the simultaneous measurement of the phase refractive index and the group refractive index, the condenser lens 3 is fixed, and There are two methods: a method in which the object 4 and the reference light mirror 6 are scanned in the optical axis direction, and a method in which the object 4 to be measured is fixed and the condenser lens 3 and the reference light mirror 6 are scanned in the optical axis direction. I will explain.

1) -1. Measurement Sample Scanning Method For the measurement sample scanning method, FIGS.
This will be described with reference to FIG. Figure 2 shows the measurement sample scanning method.
As shown in FIG. 3A, the light from the light source 1 is condensed on the front surface of the measuring object 4, and the optical path difference between the reference light and the signal light arm becomes zero, as shown in FIG. The position of the reference light mirror 6 is adjusted by the driving means 7. FIG. 6A shows that the light from the condenser lens 3 is focused on the vicinity of the front surface of the measurement object 4, and the position of the reference light mirror 6 is scanned at a predetermined interval. 4 shows an interference signal intensity pattern group obtained when the object 4 is scanned. Z = 0 is determined from the position of the measuring object 4 (driving means 5) at which the interference signal intensity is maximum, and the corresponding position of the reference light mirror 6 (driving means 7) is x = xF1.

Next, as shown in FIG.
Is moved to bring the measurement object 4 closer to the condenser lens 3 and focus on the rear surface of the measurement object 4. In this state, the optical path difference between the two arms of the interferometer becomes zero again as shown in FIG.
As shown in (b), the reference light mirror 6 is moved by the driving means 7 by ΔL1. FIG. 6B focuses light from the condenser lens 3 on the vicinity of the rear surface of the measurement object 4 and scans the position of the reference light mirror 6 at predetermined intervals.
7 shows a group of interference signal intensity patterns obtained when the measuring object 4 is scanned by the driving means 5. From the position of the measuring object 4 (driving means 5) at which the interference signal intensity is maximum, z
= Z1 is determined, and the corresponding position of the reference light mirror 6 (driving means 7) is x = xR1.

As shown in FIG. 4, first, the measuring object 4 (driving means 5) is moved at a distance z1 with reference to a state F ′ (thin line in the figure) in which light is focused on the front surface of the measuring object 4. When the light is converged on the rear surface only
(Solid line in the figure). When the incident angle of light with respect to the measurement object 4 is θ, the incident position is r, and the refraction angle is φ, according to Snell's law,

[0104]

(Equation 1)

There is the following relationship. From (Equation 1),

[0106]

(Equation 2)

Is obtained. Here, the aforementioned reference light mirror 6
The moving distance ΔL1 of the (driving means 7) is obtained. ΔL1 is the distance z1 between the case where the light is focused on the front surface (z = 0 surface) of the measurement object 4 (the thin line in the figure) and the measurement object 4 (the driving means 5).
When only moving and focusing on the rear surface (solid line in the figure)
In FIG. 4, it is equal to the optical path difference between the two focal points F and F ′ on the basis of z = z1. Since the phase of the convergent light (or divergent light) after passing through the condenser lens 3 can be considered as a light ray passing through the central axis of the condenser lens 3,

[0108]

(Equation 3)

The following relationship is satisfied. Here, the measurement object 4
It should be noted that the optical path difference ΔL1 changes according to the moving distance z1 because the (driving means 5) moves. From (Equation 2) and (Equation 3), t is deleted,

[0110]

(Equation 4)

Is obtained. (Equation 4) indicates that if the numerical aperture NA (= sin θ) of the condenser lens 3 is known, the refractive index n of the measurement object 4 can be obtained from the ratio of the measured value ΔL1 to the moving distance z1. I have. The thickness t is obtained from (Equation 3),

[0112]

(Equation 5)

Is obtained. That is, in FIG. 4, the light is condensed on the front surface of the measuring object 4 (the position z of the driving means 5; the focal point F '), and the position of the reference light mirror 6 (the driving means) at which the maximum interference signal intensity is obtained in this state. 7 at the position x = xF1) via the detection circuit 11 to take in the digitized signal by the PC 13, and move the driving means 5 to take in the data before and after xF1 to obtain xF1 which is the maximum light interference intensity. Identify.
Next, the measuring object 4 is brought closer to the condenser lens 3 by a distance z1 using the driving means 5 (z = z condensed on the rear surface of the measuring object 4).
1; focus F), in this state, the driving means 7 (reference light mirror 6) is adjusted so that the interference signal intensity becomes maximum again, and the position x = xR1 is specified in the same manner as in the above-mentioned xF1. The optical path difference between the two states focused on the front surface and the rear surface is ΔL1 =
xR1−xF1, and the refractive index n and the thickness t of the measurement object 4 are obtained from the two independent measurement values ΔL1 and z1.

Similarly, simultaneous measurement of the birefringence n and the thickness t can be performed. When non-polarized or randomly-polarized light is incident on a measurement object 4 having birefringence (eg, X-cut lithium niobate (LN) in which the X-axis of the crystal is perpendicular to the plane), the measurement is performed as shown in FIG. Since it is separated into two linearly polarized waves corresponding to the ordinary ray and the extraordinary ray polarized in the principal axis direction of the object 4, in-plane birefringence is not required without the need for polarization control such as a polarizer / analyzer and a polarization rotator. (Ne, no, or their difference) and thickness t can be measured simultaneously.

That is, in the case of the measuring object 4 having birefringence, the light is condensed on the front surface of the measuring object 4 (position z = 0 of the driving means 5; focal point F ') in FIG. The position of the reference light mirror 6 (the position x = xF1 of the driving means 7) at which the maximum interference signal intensity is obtained is fetched by the PC 13 via the detection circuit 11 via the detection circuit 11, and the driving means 5
Is moved to capture the data before and after xF1, and identify xF1 that has the maximum optical interference intensity. Next, the measuring object 4 is brought closer to the condenser lens 3 by using the driving means 5 and corresponds to an ordinary ray and an extraordinary ray which are condensed on the rear surface of the measuring object 4 appearing due to the characteristics of the birefringent measuring object 4. Two points (z = z1
(1), z1 (2); focus F) are specified (see FIG. 10),
For these states of z = z1 (1) and z1 (2), the driving means 7 (reference light mirror 6) so that the interference signal intensity becomes maximum again.
And adjust the corresponding position x = xR1 (1), xR1 (2) to xF1
Identify as above. The optical path difference between the two states focused on the front surface and the rear surface is ΔL1 (1) = xR1 (1) −xF1, ΔL1 (2) = xR1
(2) −xF1, ΔL1 (1), ΔL1 (2) and z1 (1), z1
(2) The in-plane birefringence (ne, no, or a difference between them) and the thickness t of the measurement object 4 are obtained from the two independent measurement values corresponding to (2).

By the above measurement, the desired amount ΔL1 (= xR1
−xF1) and z1 are obtained, (Equation 4) and (Equation 5)
Can be used to calculate the refractive index (birefringence) n and the thickness t of the measurement object 4.

However, it should be noted that the refractive index n obtained here is the group refractive index ng. Low coherence light with oscillation wavelength spread as a light source must be considered as a wave packet, and the refractive index obtained by the above measurement
n is a refractive index (= group refractive index ng) including the wavelength dispersion of the refractive index of the object to be measured. Snell's law is the phase index n
p, since the optical path length of this interferometer follows the group refractive index ng, (Equation 2) and (Equation 3) become

[0118]

(Equation 6)

[0119]

(Equation 7)

Is obtained. here,

[0121]

(Equation 8)

There is the following relationship. λc is the oscillation center wavelength of the light source. From Equations (6) to (8), t is eliminated, and as a linear approximation of δn1,

[0123]

(Equation 9)

[0124]

(Equation 10)

Is obtained. Now, the correction term 2δn1 included in (Equation 9) is unknown because the chromatic dispersion is originally unknown, and np cannot be calculated. Therefore, it is necessary to examine the relationship between chromatic dispersion and phase refractive index by experiment (FIG. 7). The measurement object to be examined has a measurement wavelength range sufficiently distant from the absorption edge and shows normal dispersion (dispersion as given by the Sellmeier equation). From FIG.
It can be seen that np and dnp / dλ have an exponential relationship. Therefore, considering that chromatic dispersion is 0 in the atmosphere (np = 1), δn1 can be expressed by a function of (Equation 11) with respect to np.

[0126]

[Equation 11]

In (Equation 11), a and b are constants determined from experiments. Here, when approximation of ζ2 << 1 and δn1 << 1 in (Equation 9), the first-order approximate value of np is:

[0128]

(Equation 12)

(Equation 12) (Equation 11), (Equation 1)
From 2), δn1 can be expressed only by the measured values ΔL1 and z1,

[0130]

(Equation 13)

From the two actually measured values ΔL 1 and z 1, np and t can be calculated using (Equation 9), (Equation 13) and (Equation 6). However, the NA (ζ) of the condenser lens here is the thickness
A sample whose t and phase refractive index np are known is measured, and is obtained from (Equation 14).

[0132]

[Equation 14]

To determine the constants a and b in (Equation 11),
What is necessary is just to obtain np and ng and the difference Δn1 between them by an experiment on a measurement target whose t is known, and plot the measured values (Δn1, np−1) on a log-log graph. That is, taking the logarithm of both sides of (Equation 11),

[0134]

(Equation 15)

Therefore, b can be determined from the slope and a can be determined from the intercept of np = 2. However, in this measurement, ζ and t
Since is known, from (Equation 6) and (Equation 7), (Equation 1)
6), (Equation 17) and (Equation 18) are obtained.

[0136]

(Equation 16)

[0137]

[Equation 17]

[0138]

(Equation 18)

When the constants a and b are determined by the above-described method, the condensing lens of the calculation formula (Equation 9) including the correction term δn1 is obtained.
Calibrate NA (ζ). By transforming (Equation 9),

[0140]

[Equation 19]

Here, δn1 follows (Equation 13), and the values of a and b are given by (Equation 15).

Once the calibration value of ζi is determined, the measured values (z1, ΔL
Based on (1) and (Equation 20),

[0143]

(Equation 20)

The phase refractive index np is obtained, and the thickness t can be calculated from Equation (21) obtained by modifying Equation (6).

[0145]

(Equation 21)

Therefore, in order to obtain the phase refractive index np and the thickness t, and the birefringence (np or Δnp) and the thickness t of the object 4 to be measured, the thickness t and the phase refractive index np are known in advance. By measuring the transparent material, (Equation 13)
Using the determination of constants a and b in
As long as the NA (= ζi) of the condenser lens is calibrated, the light is focused on the front surface of the measuring object 4 (position z = 0 of the driving means 5; focal point F ′) in FIG. The position of the reference light mirror 6 where the signal intensity is obtained (the position x = xF of the driving means 7)
1) is fetched by a personal computer (hereinafter, PC) 13 through a photodetection circuit 11 by a photodetector circuit 11, and the driving means 5 is moved to fetch data before and after xF1 so that the maximum light interference intensity is obtained. Specify xF1. Next, the measuring object 4 is brought closer to the condenser lens 3 by a distance z1 using the driving means 5 (z = z condensed on the rear surface of the measuring object 4).
1; focus F), in this state, the driving means 7 (reference light mirror 6) is adjusted so that the interference signal intensity becomes maximum again, and the position x = xR1 is specified in the same manner as in xF1 described above. The optical path difference between the two states focused on the front surface and the rear surface is ΔL1 =
xR1−xF1, and from the two independent measured values ΔL1 and z1, based on (Equation 20), (Equation 13) and (Equation 21), the phase refractive index np and the thickness of the object 4 to be measured t can be calculated.

Similarly, in the case of the measuring object 4 having birefringence, the light is condensed on the front surface of the measuring object 4 in FIG. 4 (the position z = 0 of the driving means 5; the focal point F '). The position of the reference light mirror 6 (the position x = xF1 of the driving means 7) at which the maximum interference signal intensity is obtained is fetched by the PC 13 via the detection circuit 11 and the digitized signal is taken in, and the driving means 5 is moved. The data before and after xF1 is fetched, and xF1 having the maximum optical interference intensity is specified. Next, the measuring object 4 is brought closer to the condenser lens 3 by using the driving means 5 and corresponds to the ordinary ray and the extraordinary ray which are condensed on the rear surface of the measuring object 4 which appears due to the characteristics of the birefringent measuring object 4. Two points (z = z1 (1), z
1 (2); focus F) is specified (see FIG. 10). For these states of z = z1 (1) and z1 (2), the driving means 7 (reference light) is set so that the interference signal intensity becomes maximum again. The mirror 6) is adjusted, and the corresponding position x = xR1 (1), xR1 (2) is specified in the same manner as xF1. The optical path difference between the two states focused on the front surface and the rear surface is ΔL1 (1) = xR1 (1) −xF1, ΔL1 (2) = xR1
(2) −xF1, ΔL1 (1), ΔL1 (2) and z1 (1), z1
From the two independent measured values corresponding to (2), the in-plane birefringence (nep, nop, nop, and np) of the measurement object 4 is calculated based on (Equation 20), (Equation 13), and (Equation 21). Or their difference)
And the thickness t can be calculated.

For an object whose thickness is known, two independent measured values ΔL1 and z1 obtained by the same measurement as above are obtained, together with ζ obtained by (Equation 14),
By substituting into (Equation 16) and (Equation 17), the phase refractive index np and the group refractive index ng of the measurement object 4 can be calculated.

Here, ζ, constants a, b and ζ used here
As for i, if the same light source 1 and condenser lens 3 are used, a value obtained by a lens scanning method described below can be used.

1) -2. Lens scanning method The lens scanning method will be described with reference to FIGS. In the lens scanning method, as shown in FIG. 2C, first, light from the light source 1 is condensed on the front surface of the measurement object 4 and the optical path difference between the reference light and the signal light arm is reduced to zero.
As shown in FIG. 3C, the position of the reference light mirror 6 is adjusted by the driving unit 7. FIG. 8A focuses light from the condenser lens 3 on the vicinity of the front surface of the measurement object 4 and scans the position of the reference light mirror 6 at predetermined intervals.
4 shows a group of interference signal intensity patterns obtained when the condensing lens 3 is scanned by the driving unit 8. From the position of the condenser lens 3 (driving means 8) at which the interference signal intensity becomes maximum, z
= 0, and the position of the reference light mirror 6 (drive means 7) corresponding to this is x = xF2. Next, as shown in FIG. 2D, the driving means 8 is moved to bring the condenser lens 3 close to the measurement object 4 and focus on the rear surface of the measurement object 4. In this state, as shown in FIG. 3D, the reference light mirror 6 is moved by ΔL2 by the driving means 7 so that the optical path difference between the two arms of the interferometer becomes zero again. FIG.
3B, the light from the condenser lens 3 is focused on the vicinity of the rear surface of the measurement object 4, and the position of the reference light mirror 6 is scanned at a predetermined interval by the driving unit 7, and the driving unit 8
3 shows an interference signal intensity pattern group obtained when the condenser lens 3 is scanned. Z = z2 is determined from the position of the condenser lens 3 (driving means 8) at which the interference signal intensity becomes maximum, and the corresponding position of the reference light mirror 6 (driving means 7) is x = xR2.

FIG. 5 shows the principle of the lens scanning method. From this, it can be seen that (Equation 22) is obtained.

[0152]

(Equation 22)

Since ΔL2 is the optical path difference between the focal points F and F ′ on the rear surface and the front surface of the object 4 to be measured, it is constant regardless of z2 and is given by (Equation 23).

[0154]

(Equation 23)

As described above, when the position of the measuring object 4 is fixed with respect to the demultiplexing / combining means 2 with respect to the light from the light source 1, the condensing lens 3 (driving means 8) between them is moved. It should be noted that the movement does not change the optical path difference ΔL2. Here, from (Equation 22) and (Equation 23), the refractive index n
Is given by (Equation 24),

[0156]

(Equation 24)

The thickness t is

[0158]

(Equation 25)

Is obtained. That is, in FIG. 5, first, light is condensed on the front surface of the measuring object 4 (the position z of the driving means 8 =
0; focal point F '), and the position of the reference light mirror 6 (position x = xF2 of the driving means 7) at which the maximum interference signal intensity is obtained in this state is specified in the same manner as in the measurement sample scanning method. Next, the condensing lens 3 is brought closer to the measurement object 4 by z2 using the driving means 8, and condensed on the rear surface of the measurement object 4 (z = z2; focal point F). In this state, the driving means 7 (reference light mirror 6) is adjusted so that the interference signal strength becomes maximum again, and the position x = x
R2 is specified in the same manner as in the measurement sample scanning method described above. The optical path difference between the two states focused on the front surface and the rear surface is ΔL2 = xR
2−xF2, and the refractive index n and the thickness t of the measuring object 4 are obtained from the two independent measured values ΔL2 and z2.

Similarly, simultaneous measurement of birefringence n and thickness t can be performed. When non-polarized light or random-polarized light is incident on the measurement object 4 having birefringence, the measurement is performed as shown in FIG. 11 (for example, X-cut lithium niobate (LN) in which the X axis of the crystal is perpendicular to the plane). Since it is separated into two linearly polarized waves corresponding to an ordinary ray and an extraordinary ray polarized in the principal axis direction of the object 4, in-plane birefringence is not required without a polarization control by a polarizer / analyzer, a polarization rotator, or the like. (Ne, no, or their difference) and thickness t can be measured simultaneously.

That is, in the case of the measuring object 4 having birefringence, the light is condensed on the front surface of the measuring object 4 in FIG. 5 (position z = 0 of the driving means 8; focal point F '). In the same manner as described above, data near x = xF2 is fetched, and the position of the reference light mirror 6 (the position x = xF2 of the driving means 7) at which the maximum interference signal intensity is obtained is specified. Next, the condensing lens 3 is brought close to the measurement object 4 by using the driving means 8, and corresponds to the ordinary ray and the extraordinary ray which are condensed on the rear surface of the measurement object 4 which appears due to the characteristics of the measurement object 4 having birefringence. Two points (z = z2
(1), z2 (2); focal point F) are respectively specified (see FIG. 11). For these states of z = z2 (1), z2 (2), the driving means is set so that the interference signal intensity becomes maximum again. 7 (reference light mirror 6), and adjust the position x = xR2 (1), xR2
Specify (2). The optical path difference between the two states focused on the front surface and the rear surface is ΔL2 (1) = xR2 (1) −xF2, ΔL2 (2) = xR2
(2) −xF2, ΔL2 (1), ΔL2 (2) and z2 (1), z2
(2) The in-plane birefringence (ne, no, or a difference between them) and the thickness t of the measurement object 4 are obtained from the two independent measurement values corresponding to (2).

From the above measurement, the desired amount ΔL2 (= xR2
−xF2) and z2 are obtained, (Equation 24), and (Equation 2)
Based on 5), the refractive index (birefringence) n and thickness t of the measurement object 4 can be calculated.

However, it should be noted that the refractive index n obtained here is the group refractive index ng, as in the above-described sample scanning method. The low coherence light having the oscillation wavelength spread as the light source needs to be considered as a wave packet, and the refractive index n obtained by the above measurement is a refractive index including the wavelength dispersion of the refractive index of the measurement object (= group refractive index ng). ). Therefore, considering the wavelength dispersion of the refractive index of the measurement object,

[0164]

(Equation 26)

It can be seen that Further, since ΔL2 is the optical path difference between the focal points F and F ′ on the rear surface and the front surface of the measurement object 4, it becomes constant regardless of z2,

[0166]

[Equation 27]

Is as follows. here,

[0168]

[Equation 28]

Λc is the oscillation center wavelength of the light source. From (Equation 26), (Equation 27) and (Equation 28), t
And as a linear approximation of δn2,

[0170]

(Equation 29)

[0171]

[Equation 30]

Is obtained. Correction term 2δ included in (Equation 29)
Since n2 is originally unknown because the chromatic dispersion is unknown, np cannot be calculated. Therefore, similarly to the measurement sample scanning method, the relationship between the chromatic dispersion and the phase refractive index is examined by an experiment, and considering that the chromatic dispersion is 0 in the atmosphere (np = 1), δn2 is calculated as follows with respect to np. Expressed as a functional form.

[0173]

(Equation 31)

In (Equation 31), a and b are constants determined from experiments. Here, when approximation of ζ2 << 1 and δn2 << 1 in (Equation 25), the first-order approximate value of np is:

[0175]

(Equation 32)

Is as follows. From (Equation 31) and (Equation 32), δ
n2 can be represented only by the measured values ΔL2 and z2,

[0177]

[Equation 33]

From the two actually measured values ΔL2 and z2, np and t can be calculated using (Equation 29), (Equation 33) and (Equation 26). However, the NA (ζ) of the condenser lens here is
Measure a sample whose thickness t and phase index np are known,

[0179]

(Equation 34)

From this, it is determined. In order to determine the constants a and b in (Equation 31), np is determined by an experiment on a measurement target whose t is known.
And ng and the difference δn2 are obtained, and the measured value (δn2, np−
1) may be plotted on a log-log graph. That is,
Taking the logarithm of both sides of (Equation 31),

[0181]

(Equation 35)

Therefore, b can be determined from the slope and a can be determined from the intercept of np = 2. However, in this measurement, ζ and t
Since is known, from (Equation 26) and (Equation 27),

[0183]

[Equation 36]

[0184]

(37)

[0185]

(38)

Is as follows. Further, the constant a,
When b is determined, a calculation formula including the correction term δn2 ((Equation 2)
9) Calibrate the condenser lens NA (ζ). By transforming (Equation 29),

[0187]

[Equation 39]

Here, δn2 follows (Equation 33), and the values of a and b are given by (Equation 35).

Once the calibration value of ζi is determined, the measured value (z2, ΔL
Based on 2)

[0190]

(Equation 40)

From the above, the phase refractive index np is obtained, and the thickness t
Is an expression obtained by transforming (Equation 26),

[0192]

[Equation 41]

Can be calculated from Therefore, the phase refractive index np and the thickness t of the measurement object 4 and the birefringence (np or Δnp)
In order to determine the thickness t and the thickness t and the phase refractive index np, various transparent materials whose thicknesses are known are measured in advance to determine the constants a and b in (Expression 33) and to use (Expression 39). As long as the NA (= ζi) of the condenser lens is calibrated, light is first focused on the front surface of the measurement object 4 (position z = 0 of the driving means 8; focal point F ′) in FIG. The position of the reference light mirror 6 where the maximum interference signal intensity is obtained in the state (the position x = xF2 of the driving means 7) is specified in the same manner as in the measurement sample scanning method. Next, the condensing lens 3 is
Is brought closer to the measurement object 4 by z2, and focused on the rear surface of the measurement object 4 (z = z2; focal point F). In this state, the driving means 7 (reference light mirror 6) so that the interference signal strength becomes maximum again.
Is adjusted, and the position x = xR2 is specified in the same manner as in the measurement sample scanning method. The optical path difference between the two states focused on the front surface and the rear surface is ΔL2 = xR2−xF2. From the two independent measurement values ΔL2 and z2, (Expression 40), (Expression 33) and (Expression 41) are obtained. Based on this, the phase refractive index np and the thickness t of the measurement object 4 can be calculated.

Similarly, in the case of the measuring object 4 having birefringence, the light is condensed on the front surface of the measuring object 4 in FIG. 5 (position z = 0 of the driving means 8; focal point F '). In the same manner as described above, data near x = xF2 is fetched, and the position of the reference light mirror 6 (the position x = xF2 of the driving means 7) at which the maximum interference signal intensity is obtained is specified. Next, the condensing lens 3 is brought close to the measurement object 4 by using the driving means 8, and corresponds to the ordinary ray and the extraordinary ray which are condensed on the rear surface of the measurement object 4 which appears due to the characteristics of the measurement object 4 having birefringence. Two points (z = z2 (1), z
2 (2); focus F) is specified (see FIG. 11). For these states of z = z2 (1) and z2 (2), the driving means 7 (reference light) is set so that the interference signal intensity becomes maximum again. The mirror 6) is adjusted, and the position x = xR2 (1) and xR2 (2) corresponding to each are specified. The optical path difference between the two states focused on the front surface and the rear surface is ΔL2 (1) = xR2 (1) −xF2, ΔL2 (2) = xR2 (2) −xF2, and these ΔL2 (1), ΔL2 (2) And z2 (1) and z2 (2), respectively, from two corresponding independent measured values (Equation 40), (Equation 3)
Based on 3) and (Equation 41), the in-plane birefringence (nep, nop, or a difference between them) and the thickness t of the measurement object 4 can be calculated.

Further, for the measurement object whose thickness is known, two independent measurement values ΔL2 and z2 obtained by the same measurement as above are obtained together with ζ obtained by (Expression 34),
By substituting into (Equation 36) and (Equation 37), the phase refractive index np and the group refractive index ng of the measurement object 4 can be calculated.

Here, ζ, constants a, b and ζ
As for i, if the same light source 1 and condenser lens 3 are used, a value obtained by the measurement sample scanning method can be used.

2) As a method of measuring the birefringence of the object to be measured, a scanning method of a measurement sample: a method of fixing a reference light mirror and scanning the object to be measured in the optical axis direction A scanning method of a reference light mirror: an object to be measured Is fixed, and the reference light mirror is caused to scan in the optical axis direction.

FIG. 12 is a diagram showing a basic system configuration of birefringence measurement according to an embodiment of the present invention. In FIG.
1 have the same functions, and the difference between FIG. 12 and FIG. 1 is that the condenser lens 3 and the driving means 8 for holding and mounting the condenser lens 3 are not provided. In this figure, light emitted from a light source 1 is transmitted through a lens 12a to a light source 1
Is split by a splitting / combining means 2 for splitting / combining light from the light source, and one of the lights is applied to a measurement object 4 held and mounted on a driving means 5. On the other hand, the other light is held and mounted on the driving means 7 and is applied to the reference light mirror 6 fixed to the vibrator 9. Vibration at a frequency f and a predetermined amplitude is applied to the vibrator 9 to phase-modulate the reflected light (reference light) from the reference light mirror 6. The reflected light (signal light) from the measurement object 4 and the reference light from the reference light mirror 6 are multiplexed by the demultiplexing / combining means 2 and are passed through the lens 12b to the light receiving element 1
It is detected at 0. The detection signal is converted into a digital signal by the detection circuit 11, and the data of the detection circuit 11 is
And is processed.

2) -1. Measurement Sample Scanning Method The measurement sample scanning method will be described with reference to FIGS. In the measurement sample scanning method, FIG.
As shown in (2), the measurement object 4 is irradiated with unpolarized or random polarized light, and the light path difference between the reference light and the signal light arm of the light (signal light) reflected on the front surface of the measurement object 4 becomes zero. As described above, the measuring object 4 is moved by the driving means 5 and the data near x = 0 is taken in the same manner as described above, and the position where the maximum interference signal strength is obtained is specified (z = 0). Next, the driving means 5 is moved as shown in FIG.
The measuring object 4 is brought closer to the demultiplexing / combining means 2 so that the optical path difference between the reflected light (signal light) from the rear surface of the measuring object 4 and the reference light arm from the reference light mirror 6 becomes zero again. Then, the measuring object 4 is moved by the driving means 5, and data near z = z3 is fetched in the same manner as described above, and the position where the maximum interference signal intensity is obtained is specified. Measurement object 4 at this time
The moving distance of (driving means 5) is z3. This z3 becomes the optical path difference (refractive index n × thickness t) (see FIG. 14).

Here, when the object 4 to be measured is a medium having birefringence, when the driving means 5 is moved to bring the object 4 closer to the demultiplexing / combining means 2, FIG. For example,
X-cut lithium niobate (L
As shown in N)), the reflected light (signal light) from the rear surface is separated into two linearly polarized waves corresponding to the ordinary ray and the extraordinary ray polarized in the principal axis direction due to the birefringence characteristic of the measurement object 4. Can be obtained.

That is, on the front surface of the measuring object 4,
After adjusting the optical path difference between the reference light and the signal light arm to be 0, the object 4 to be measured is scanned in the direction of the demultiplexing / combining means 2, and as shown in FIG. At positions (z3 (1), z3 (2)) corresponding to the two linearly polarized waves of object 4,
The interference light intensity is maximized, and information on each optical path length (refractive index n × thickness t) can be obtained. Therefore, when the thickness t is known, the in-plane birefringence (ne, no, or a difference between them) of the measurement object 4 can be evaluated.

Here, the refractive index (birefringence) is the group refractive index.
ng. 2) -2. Reference Light Mirror Scanning Method The reference light mirror scanning method will be described with reference to FIGS.

In the reference light mirror scanning method, as shown in FIG. 13C, unpolarized or random polarized light is irradiated on the measurement object 4 and light (signal light) reflected on the front surface of the measurement object 4 In the above, the reference light mirror 6 is moved by the driving means 7 so that the optical path difference between the reference light and the signal light arm becomes zero, and the data near x = xF3 is taken in the same manner as described above to obtain the maximum interference signal strength. Specify the position (x = xF3). Next, the driving means 7 is moved as shown in FIG.
The reference light mirror 6 is moved away from the demultiplexing / combining means 2 so that the optical path difference between the reflected light (signal light) from the rear surface of the measuring object 4 and the reference light arm from the reference light mirror 6 becomes zero again. Then, the reference light mirror 6 is moved by the driving means 7 to fetch data near x = xR3 in the same manner as described above, and the position where the maximum interference signal intensity is obtained is specified (x = xR3). At this time, the moving distance of the reference light mirror 6 (driving means 7) is set to ΔL3 (= xR3
−xF3). This ΔL3 is the optical path difference (refractive index n × thickness t) (see FIG. 16).

Here, when the object 4 to be measured is a medium having birefringence, the driving means 7 is moved and the reference light mirror 6 is moved.
Is moved away from the demultiplexing / combining means 2, as shown in FIG. 17 (for example, X-cut lithium niobate (LN) in which the X axis of the crystal is perpendicular to the plane), the birefringence of the object 4 to be measured Due to the characteristics, reflected light (signal light) from the rear surface, which is separated into two linearly polarized waves corresponding to an ordinary ray and an extraordinary ray polarized in the principal axis direction, can be obtained.

That is, on the front surface of the measuring object 4,
After adjusting the optical path difference between the reference light and the signal light arm to be 0, the object 4 to be measured is scanned in the direction of the demultiplexing / combining means 2, and as shown in FIG. At the position (ΔL3 (1), ΔL3 (2)) corresponding to each linearly polarized wave of the object 4,
The interference light intensity is maximized, and information on each optical path length (refractive index n × thickness t) can be obtained. Therefore, when the thickness t is known, the in-plane birefringence (ne, no, or a difference between them) of the measurement object 4 can be evaluated.

Here, the refractive index (birefringence) is the group refractive index.
ng. 3) In order to evaluate the cured state or degree of curing of the curable resin using the average refractive index in the thickness direction of the curable resin as an index, it is necessary to first understand the characteristics of various curable resins. is there. Generally curable resin (ultraviolet curable resin, thermosetting resin, electron beam curable resin, catalyst curable resin, coating film, etc.)
Changes in the refractive index (increase or decrease) due to the effects of curing shrinkage during the curing process from liquid to solid
And at some point an equilibrium is reached. However, this change in the refractive index is at most about 0.02. Therefore, in order to evaluate the cured state or the degree of cure of the curable resin with the refractive index, the resolution of the refractive index which is one digit higher than the amount of change in the refractive index of the resin is required. Further, for a resin such as an ultraviolet curable resin, which cures from the irradiation surface side of the ultraviolet light, the curing reaction state is greatly affected by the thickness of the resin, so that the refractive index in the thickness direction is not uniform. Various situations are assumed, such as a mixture of a cured portion and an uncured portion. Under such circumstances, it is necessary to use the averaged refractive index as an index in the thickness direction of the resin, and it is necessary to accurately grasp the thickness of the resin. In consideration of these facts, in order to evaluate the curing process (cured state or degree of curing) of the curable resin from a liquid state to a solid state by a refractive index, the refractive index n and the thickness t described in 1) are used. (Simultaneous measurement method or lens scanning method) can be used.

As the light source 1, in the simultaneous measurement of the refractive index and the thickness, and the simultaneous measurement of the phase refractive index and the group refractive index,
Linearly polarized light, unpolarized light or random polarized light can be used, and non-polarized or random polarized light can be used in birefringence measurement, birefringence and thickness measurement. As a specific example of the light source 1, a superluminescent diode (SL
D), the light from a white light source (halogen lamp or xenon lamp) is spectrally separated in a specific wavelength range by a monochromator, the laser diode (LD) driven by the injection current below the threshold, the light emitting diode, etc. Those having a size of 30 μm or less can all be used. Light source 1
The wavelength is not limited, and all the wavelengths from ultraviolet light to infrared light whose coherence length is 30 μm or less can be used. Therefore, it is also possible to scan the light wavelength from a short wavelength to a long wavelength using the light source 1 which is a combination of a white light source and a monochromator to measure the wavelength characteristic (wavelength dispersion) of the measurement object (medium). In addition, as in the case of using the light source 1, light obtained by dispersing a white light source by a monochromator is used to measure wavelength characteristics (wavelength dispersion) by using a plurality of laser diodes having different oscillation center wavelengths. Is also possible. The light source 1
The output of is stable without fluctuation, and multiplexes and interferes the signal light from the measurement object and the reference light from the reference light mirror. preferable.

The demultiplexing / combining means 2 demultiplexes the light from the light source 1 to the measuring object 4 and the reference light mirror 6, and reflects the reflected light (signal light) from the measuring object 4 and the reference light mirror 6. Multiplexing means for multiplexing the reflected light (reference light) from the light and emitting the light toward the light receiving element 10. Specific examples of the multiplexing / demultiplexing means 2 include a beam splitter (BS) and a chrome half mirror. , Aluminum half mirror, dielectric multilayer half mirror,
Single mode fiber couplers, optical waveguides, directional couplers, etc. can be used. Among them, BS and single mode fiber couplers are preferable from the viewpoint of operability such as optical axis alignment. The demultiplexing / combining means 2 is not limited to these, but may be any as long as it fulfills the functions described above. Needless to say, it is necessary to optimize the demultiplexing / combining means 2 so that absorption and loss are minimized with respect to the working wavelength, depending on the working wavelength of the light source 1. The demultiplexing / combining means 2 is desirably provided with an anti-reflection (AR) coating in order to minimize the reflection of incident light and increase the amount of transmitted light. As the AR coating, a multilayer coating is preferable.

The condensing lens 3 is a lens for condensing the light from the demultiplexing / combining means 2 on the object 4 to be measured.
Inorganic substances such as glass and optical crystals and polymethyl methacrylate (PMMA), polycarbonate (PC)
Plano-convex lens, bi-convex lens,
A cylindrical lens, a spherical lens, or the like can be used. Above all, B having extremely good transmittance for wavelengths in the visible region and the near infrared region.
Condensing lens 3 using K7, condensing lens 3 using quartz having good transmittance for wavelengths in the ultraviolet, visible, and near-infrared regions, a small coefficient of thermal expansion, and being stable to temperature. Is preferable. In addition, these condenser lenses are desirably provided with an AR coating in order to minimize the reflection of incident light and increase the amount of transmitted light. As the AR coating, a multilayer coating is preferable. Note that an objective lens for a metal microscope may be used as the condenser lens 3 having good transmittance and the like.

The object 4 to be measured may be glass (for example, quartz glass, soda-lime glass, borosilicate glass, lead glass, etc.) or polymer (for example, PMMA, PC, polyethylene terephthalate, polybutylene terephthalate, methyl methacrylate, epoxy Resin, polyfluoroacrylate,
Silicon resin, melamine resin, ultraviolet curable resin, electron beam curable resin, catalyst curable resin, thermosetting resin, etc.), crystalline materials (eg, lithium niobate, lithium tantalate, sapphire, KDP, ADP, calcite, etc.) and transparent containers The liquid material and the living tissue (for example, cornea, lens, nail, etc.) therein, and the like. Here, the front surface and the rear surface of the measuring object 4 do not necessarily have to be mirror surfaces, but can be measured even if they are rough surfaces. Further, the measurement object 4 is not limited to the above-mentioned glass, polymer, or crystal material, but may be a multilayer film of these materials. Further, the measuring object 4 may be a medium that does not completely absorb light, and even if it is a scattering medium in which a scatterer is interposed in the medium, only the reflected straight light (signal light) is extracted. And can be measured. Furthermore, the measuring object 4 does not necessarily need to be a parallel plate, and can measure even a medium having a front surface or a rear surface with a slope or curvature.

[0211] The driving means 5 is a driving means for holding and mounting the measuring object 4, and is for scanning the measuring object 4 in the optical axis direction. As the driving means 5, a fine movement stage such as a pulse stage or a linear motor stage can be used. These fine movement stages have a resolution of 1 μm or less and a repetitive positioning accuracy of ± 1 μm to improve measurement accuracy.
In the following, it is desirable to have a straightness of 1 μm or less, a parallelism of 1 μm or less, a yawing of 5 sec or less, and a pitching of 5 sec or less. The driving means 5 is not limited to the fine movement stage described above, but may be any device as long as the characteristics described above are satisfied.

The reference light mirror 6 receives and reflects the light of the light source 1 demultiplexed by the demultiplexing / combining means 2. The reflected light (reference light) is incident on the light receiving element 10 via the demultiplexing / combining means 2. The reference light mirror 6 is a chrome total reflection mirror, an aluminum total reflection mirror, a dielectric multilayer total reflection mirror, or the like, and is not particularly limited. Here, the area and the thickness of the reference light mirror 6 should be optimized according to the beam diameter of the light applied to the reference light mirror 6 and the generating force of the oscillator 9 that modulates the applied light. And the area is preferably three times or less the beam diameter of the light applied to the reference light mirror 6 (light beam diameter: 8 m
If it is mφ, the area is 24 mmφ or less), and the thickness is preferably 1 mm or less. The reference light mirror 6 is
It is needless to say that it is necessary to optimize the reflection characteristics according to the wavelength of the light used by the light source 1 so as to maximize the reflection characteristics.

The driving means 7 is a driving means for holding and mounting the reference light mirror 6, and is for scanning the reference light mirror 6 in the optical axis direction. As the driving means 7, a fine movement stage such as a pulse stage and a linear motor stage can be used. These fine movement stages have a resolution of 1 μm or less and a repetitive positioning accuracy of ± 1 μm to improve measurement accuracy.
m, a straightness of 1 μm or less, a parallelism of 1 μm or less, a yawing of 5 sec or less, and a pitching of 5 sec or less are desirable. The driving means 7 is not limited to the fine movement stage described above, but may be any device as long as it satisfies the characteristics described above.

The driving means 8 is a driving means for holding and mounting the condenser lens 3, and is for scanning the condenser lens 3 in the optical axis direction. As the driving means 8, a fine movement stage such as a pulse stage or a linear motor stage can be used. These fine movement stages have a resolution of 1 μm or less and a repetitive positioning accuracy of ± 1 μm to improve measurement accuracy.
In the following, it is desirable to have a straightness of 1 μm or less, a parallelism of 1 μm or less, a yawing of 5 sec or less, and a pitching of 5 sec or less. The driving means 8 is not limited to the fine movement stage described above, but may be any as long as it satisfies the characteristics described above.

The vibrator 9 modulates the phase of the light applied to the reference light mirror 6. The phase modulation applies a vibration having an amplitude of λc / 2 or less of the oscillation center wavelength λc of the light source and a frequency of 100 Hz or more. As the vibrator 9, a piezoelectric actuator (for example, a laminated piezoelectric actuator, a bimorph-type piezoelectric actuator, a monomorph-type piezoelectric actuator, or the like) or an electromagnetic actuator (for example, a voice coil or the like) can be used. Above all, a small-sized and light-weight laminated piezoelectric actuator that can obtain a large displacement amount at a low voltage, generate a large force, and has good responsiveness is preferable. Here, in selecting the vibrator 9, it is needless to say that the oscillation center wavelength λc of the used light source and the area and thickness (weight) of the reference light mirror 6 are important parameters. It is necessary to select an optimum vibrator 9 according to the specifications of the mirror 6. Here, as the vibrator 9, a piezoelectric actuator (for example, a laminated piezoelectric actuator, a bimorph-type piezoelectric actuator, a monomorph-type piezoelectric actuator, or the like) or an electromagnetic actuator (for example, a voice coil or the like) is used. However, the present invention is not limited thereto, and it is sufficient that the light applied to the reference light mirror 6 can be phase-modulated stably at a predetermined frequency and amplitude.

The light receiving element 10 receives the reflected light (signal light) from the measuring object 4 multiplexed by the demultiplexing / combining means 2 and the reference light from the reference light mirror 6. 10 is a silicon photodiode, silicon
PIN photodiodes, silicon avalanche photodiodes, GaAsP photodiodes (diffusion type), GaAsP photodiodes (Schottky type), GaP photodiodes, Ge photodiodes, Ge avalanche photodiodes, InGaAs-PIN photodiodes, and the like can be used. Here, it is needless to say that it is necessary to select an optimal light receiving element 10 according to the wavelength used, the output intensity, and the phase modulation frequency of the light source 1. Above all, a wavelength of 400 nm
A silicon photodiode is preferable for detection of wavelengths from 700 nm to 1000 nm, and a Ge photodiode is preferable for detection of wavelengths from 700 nm to 1700 nm. Here, as the light receiving element 10, a silicon photodiode, a silicon PIN photodiode, a silicon avalanche photodiode, a GaAsP photodiode (diffusion type), a GaAsP photodiode (Schottky type), a GaP photodiode, a Ge photodiode, a Ge avalanche Although the photodiode, the InGaAs-PIN photodiode and the like have been described, the light receiving element 10 is not limited thereto, and the reference light mirror 6 phase-modulated by the vibrator 9 is used.
Any signal can be used as long as it can perform heterodyne detection of the reference light from the optical disc and the signal light from the object 4 to be measured.

The detecting circuit 11 has a function of converting an analog detection (detection) signal from the light receiving element 10 into a digital signal. Specifically, the detection circuit 11 includes an amplifier, a low-pass / high-pass filter, a sampling and holding circuit, and an A / D converter. Since the signal from the light receiving element 10 is a small signal, it is input to an amplifier, which is an amplifier circuit, to increase the S / N ratio. Since the output contains a noise component from the outside or a power supply, the noise is removed by a low-pass / high-pass filter for removing the noise signal. The output of the low-pass / high-pass filter is vibrated by the vibrator 9 at a constant cycle, and a necessary analog signal is held by a sampling and holding circuit for detecting a signal in synchronization with the cycle. By converting the held signal from an analog signal to a digital signal by an A / D converter, a desired digital signal can be detected. The data converted from an analog signal to a digital signal by the detection circuit 11 is taken into a personal computer (hereinafter, PC) 13. Here, the function of analog / digital conversion is included in the detection circuit 11, but the function of analog / digital conversion may be performed by the PC 13. Further, the detection circuit 11 is not limited to the above-described function, and may perform data processing before the detection (detection) signal from the light receiving element 10 is taken into the PC 13.

The lens 12a is a means for collimating the light emitted from the light source 1 and making it incident on the demultiplexing / combining means 2. The lens 12a is made of an inorganic substance such as glass or optical crystal and polymethyl meta- Acrylate (PMMA),
Plano-convex lenses, biconvex lenses, spherical lenses, and the like of a polymer material (organic material) such as polycarbonate (PC) can be used. Among them, a lens 12a using BK7 having extremely good transmittance for wavelengths in the visible and near-infrared regions, a good transmittance for ultraviolet, visible and near-infrared wavelengths, a small coefficient of thermal expansion, and a temperature It is preferable to use an inorganic condensing lens such as a lens 12a using quartz having a property stable to the light.
In addition, these condenser lenses are desirably provided with an AR coating in order to minimize the reflection of incident light and increase the amount of transmitted light. As the AR coating, a multilayer coating is preferable. Note that an objective lens for a metal microscope may be used as the lens 12a having good transmittance and the like.

The lens 12b is a means for causing the reference light from the reference light mirror 6 and the signal light from the measuring object 4 multiplexed by the demultiplexing / combining means 2 to enter the light receiving element 10. As 12b, a plano-convex lens, a biconvex lens, a spherical lens, or the like of an inorganic substance such as glass and optical crystal and a polymer material (organic substance) such as polymethyl methacrylate (PMMA) and polycarbonate (PC) can be used. Above all, a lens 12b using BK7, which has a very good transmittance for wavelengths in the visible and near-infrared regions, a good transmittance for wavelengths in the ultraviolet, visible, and near-infrared regions, a small coefficient of thermal expansion, and a temperature It is preferable to use an inorganic condensing lens such as a lens 12b using quartz having a property stable to the light. In addition, these condenser lenses are desirably provided with an AR coating in order to minimize the reflection of incident light and increase the amount of transmitted light. As the AR coating, a multilayer coating is preferable. Note that an objective lens for a metal microscope may be used as the lens 12b having good transmittance and the like.

The PC 13 controls the driving means 5, 7, 8 via the stage controller 14, and the detection circuit 1
1 and the position data from the stage controller 14 are taken in, and the measurement result is processed. Specifically, first, the peak of the maximum interference light intensity on the front surface of the measuring object 4 is specified from the signal of the detecting circuit 11, and the measuring object 4 (driving means 5: z = 0) or the condensing lens in that state is specified. 3 (driving means 8: z = 0) and the position of the reference light mirror 6 (driving means 7: x = xF1 or x = xF2) are detected from data from the stage controller 14. On the basis of this position, the measurement object 4
The peak of the maximum interference light intensity on the rear surface is specified, and the measurement object 4 (driving means 5: z = z1) or the condenser lens 3 (driving means 8: z = z2) and the reference light mirror 6 (driving) in that state. Means 7: The position of x = xR1 or x = xR2) is detected, and the measuring object 4 (driving means 5) or the condenser lens 3 is detected.
The moving distance between the front surface and the rear surface of the (drive unit 8) and the reference light mirror 6 (drive unit 7) is obtained. In the case of the measurement sample scanning method, the respective moving distances obtained here are measured object 4 (driving means 5) and reference light mirror 6 (driving means 7).
Corresponds to z1 and ΔL1 = xR1−xF1, and in the case of the lens scanning method, the moving distances of the condenser lens 3 (driving means 8) and the reference light mirror 6 (driving means 7) are z2 and Δ
L2 = xR2-xF2. These z1, ΔL1 and z2,
The independent measurement value of ΔL2 and the value of NA (= ζi) of the condenser lens 3 are expressed by (Equation 20), (Equation 21) or (Equation 36), (Equation 3)
7), and the phase refractive index np and thickness of the measurement object 4
To calculate t, the value of NA (= ζ) of the condenser lens 3 is calculated by (Equation 1)
6), (Expression 17) or (Expression 32), and (Expression 33), and the phase refractive index np and the group refractive index ng of the measurement object 4 are calculated. The type of the PC 13 is not particularly limited as long as it can perform data processing from the detection circuit 11 and the stage controller 14 described above.
In addition, the function of the PC 13 is not limited to only the data processing, and the function of the analog / digital conversion performed by the detection circuit 11 may be performed.

The stage controller 14 controls the driving means 5, 7, and 8 with high accuracy in accordance with a signal from the PC 13, and obtains accurate position information. Therefore, it is necessary to select an optimum stage controller 14 according to the resolution and positioning accuracy of the driving means 5, 7, 8 to be used. If the above-mentioned driving means 5, 7, 8 can be controlled, the model is particularly suitable. It is not limited.

Generally, a semiconductor laser diode (LD) for optical communication has an oscillation wavelength spectrum width Δλ (<0.1 n
m) is a narrow, good quality monochromatic light source. On the other hand, a superluminescent diode (SLD) is intermediate between a light emitting diode (LED) and an LD, and the oscillation wavelength spectrum of a commercially available SLD is as wide as Δλ to about 15 nm. this
An interference optical system using a light source with a wide oscillation wavelength spectrum such as an SLD is called a low coherence interference optical system, and its coherence length Δlc is only 10 μm. That is, in the SLD interference optical system, 2
The two lights (the reference light and the signal light) cannot interfere with each other unless the difference between their propagation distances (optical path lengths) is 10 μm or less.
In other words, the low coherence interference optical system can identify the difference in the light propagation distance (optical path length) with a resolution of 10 μm. From this, the low coherence interference optical system has a resolution of 10
It can be used for measuring the optical path length on the order of μm and diagnosing minute areas, and is expected to be applied to various fields (industrial field, medical field). In particular, it goes without saying that the application to the medical field will be used for various diagnoses including ophthalmic medical treatment.

Hereinafter, embodiments of the present invention will be described. (Embodiment 1) In this embodiment, a superluminescent diode (SLD) having an oscillation center wavelength λc = 850 nm is used as the light source 1 in FIG. The full width at half maximum (FWHM) of the spectrum of this SLD is Δλ = 24 nm,
The coherence length of the interferometer determined by this is Δlc = 6.
6 μm. Further, a beam splitter (BS) is used as the demultiplexing / combining means 2, and a spherical lens (× 2
0), as the driving means 5 and 7, a linear motor stage of 0.1 μm / step (ALS902 manufactured by Chuo Seiki Co., Ltd.)
-H1L), and a laminated piezoelectric actuator (manufactured by Sumitomo Metal Industries, Ltd.) was used as the vibrator 9. The vibrator 9 is given a vibration of frequency f (= 500 Hz) and amplitude λc / 2, and phase-modulates the reflected light (reference light) from the reference light mirror 6 using a Si photodiode used as the light receiving element 10.
The reflected light (signal light) from the measuring object 4 and the reference light mirror 6
Heterodyne detection was performed by multiplexing and interfering the reference light from.
The detected detection signal was converted into a digital signal, taken into a PC and subjected to data processing, and ΔL1, z1 (measurement sample scanning method) was specified. The lenses 12a and 12b use 20 × and 5 × objective lenses, respectively.

First, the thickness t (= 1026 μm) and np
The NA (= ζ) of the condenser lens 3 was calibrated using a fused quartz plate with a known (= 1.42525). In the measurement sample scanning method
z1 (= 703 μm) was actually measured, and a calibration value ζ = 0.134 was obtained using (Equation 14).

Next, the constants a and b in (Equation 13) were determined. Based on に obtained in (Equation 14) above, thickness
Various transparent materials with known t (solid materials: quartz, BaCD14, F
D60, soda glass, LiNbO3 (no), liquid material: water, glycerin, ethanol, ZEP520) were used as the measurement object 4, and the results of simultaneous measurement of ng and np are shown in Table 1 and FIG.

In FIG. 9, δn is the difference between ng and np.

[0227]

[Table 1]

The phase refractive index np and group refractive index ng in (Table 1)
From the simultaneous measurement results, the errors (Δnp and Δng) between the theoretical values and the calculated values of various materials are 0.8% or less, and simultaneous measurement of the phase refractive index np and group refractive index ng can be performed accurately. did it.

In FIG. 9, when a straight line is drawn for all the measurement points by the least square method, it is understood that the measurement points are distributed around the straight line for the solid material. At the same time, the measurement of the liquid was performed, but it is expected that the measurement point of the liquid would be on a straight line different from the solid material.

From the straight line by the least square method, a = 2.406 × 10 −2 and b = 1.692 for a solid material, while a = 4.598 × 10 −2 and b for a liquid. = 1.525.

From the constants a and b for the solid and liquid materials obtained from the above-described experiments, the values of z1 and ΔL1 of the fused quartz plate are used for the solid material, and the values of the liquid material are Assuming that the phase refractive index of water is np = 1.329, (Equation 1)
9), the NA (= ζi) of the condenser lens 3 was calibrated.

Δi = 0.114 solid material Δi = 0.123 liquid material was obtained.

The NA of a spherical lens calibrated with a fused silica plate (= ζ
i = 0.114), z1 of various measurement objects 4,
The results of calculating the phase refractive index np and the thickness t by substituting the measured values of ΔL1 into (Equation 13), (Equation 20), and (Equation 21) are shown in (Table 2).

[0234]

[Table 2]

Sapphire, X-cut LiNbO3 (ne) and X
In the cut LiTaO3 (no), the error of np was 0.7% or less, and the error of t was 0.3% or less. In addition, optical glass (FDS1), vinyl chloride plate,
As a result of measuring acrylic plate and styrene plate,
The error from the measured value of t with the micrometer gauge is 0.
It was less than 2%.

(Embodiment 2) In the present embodiment, the light of a halogen lamp is split into a light source 1 in FIG. 1 by a monochromator (SM-3, manufactured by Spectrometer Co., Ltd.), and a center wavelength λc = 850 nm. Was used. The full width at half maximum (FWHM) of the spectrum of this light is ΔΔ as in the first embodiment.
λ was adjusted to 24 nm. The coherence length of the interferometer determined by this is Δlc = 6.6 μm. In addition,
Aluminum multiplex mirror, condenser lens 3 as multiplexing means 2
A spherical lens (× 20) similar to that of Embodiment 1, 0.1 μm / step linear motor stage (ALS902-H1L, manufactured by Chuo Seiki Co., Ltd.) as drive means 5 and 8;
As the vibrator 9, a laminated piezoelectric actuator (manufactured by Tokin Co., Ltd.) was used. The vibrator 9 has a frequency f (= 500H
z), a vibration having an amplitude of λc / 2 is given, the reflected light (reference light) from the reference light mirror 6 is phase-modulated, and the reflected light (signal light) from the object 4 is measured by the Si photodiode used as the light receiving element 10. ) And the reference light from the reference light mirror 6 are combined and interfered to perform heterodyne detection. The detected detection signal was converted into a digital signal, taken into a PC, and subjected to data processing to specify ΔL2, z2 (; lens scanning method).
The lenses 12a and 12b have a magnification of 20 and 5, respectively.
A double objective lens is used.

The NA (ζ) of the condenser lens 3 and the constants a and b
Used the value calibrated in the first embodiment.

As the object 4 to be measured, X-cut LiNbO3 was measured, and z2 and ΔL2 were measured for each of birefringence (ordinary light: no, extraordinary light: ne), and the values were expressed by (Equation 36) and (Equation 37).
The results of calculating the phase refractive index np, the group refractive index ng, the phase refractive index np, and the thickness t by substituting into (Equation 33), (Equation 40), and (Equation 41) are shown in (Table 3).

[0239]

[Table 3]

In the simultaneous measurement of the phase refractive index np and the group refractive index ng, the measurement error concerning ne and no of the X-cut LiNbO3 is 0.8% or less, and the phase refractive index (birefringence) np and the thickness t In the simultaneous measurement, the phase refractive index np is set to 0.1.
The error of t was 2% or less, and the error of t was 0.6% or less.

(Embodiment 3) In the present embodiment, the light source 1 shown in FIG.
m superluminescent diode (SLD) was used. The full width at half maximum (FWHM) of the spectrum of this SLD is Δλ
= 24 nm, and the determined coherence length of the interferometer is Δlc = 6.6 μm. A beam splitter (BS) and a condenser lens 3 are used as the demultiplexing / combining means 2.
As in the first embodiment, a spherical lens (× 20) similar to that of the first embodiment, 1 μm / step pulse stage (manufactured by Chuo Seiki Co., Ltd .: MM-60X), and vibrator 9 as driving means 5 and 7
As a laminated piezoelectric actuator (Sumitomo Metal Industries, Ltd.)
Was used. The vibrator 9 has a frequency f (= 500H
z), a vibration having an amplitude of λc / 2 is given, the reflected light (reference light) from the reference light mirror 6 is phase-modulated, and the reflected light (signal light) from the object 4 is measured by the Si photodiode used as the light receiving element 10. ) And the reference light from the reference light mirror 6 are combined and interfered to perform heterodyne detection. The detected detection signal was converted to a digital signal, taken into the PC 13 and subjected to data processing to specify ΔL1, z1 (measurement sample scanning method). The lenses 12a and 12b each have 2
A 0x and 5x objective lens is used.

The values calibrated in the first embodiment were used for NA (ζ, Δi) and constants a and b of the condenser lens 3.

A human hand was measured as the object 4 to be measured. As a result, ΔL1 = 303 μm and z1 = 242 μm. From the measured values, the refractive index np = 1.924, the thickness t
= 362.5 μm.

This measured value was in good agreement with the thickness (= 359 μm) actually measured by the micrometer, and the phase refractive index np and the thickness t could be measured simultaneously and accurately.

(Embodiment 4) In the present embodiment, light from a xenon lamp is split into light sources 1 in FIG. 12 by a monochromator (SM-3, manufactured by Spectrometer Co., Ltd.).
Light having a center wavelength λc = 850 nm was used. The full width at half maximum (FWHM) of this light spectrum was adjusted to Δλ = 24 nm as in the first embodiment. The coherence length of the interferometer determined by this is Δlc = 6.6 μm. Further, as the demultiplexing / combining means 2, a single mode fiber coupler,
A linear motor stage of 0.1 μm / step (ALS902-H1L, manufactured by Chuo Seiki Co., Ltd.) is used as the driving means 5, and an X-cut LiNbO 3 whose X-axis is perpendicular to the surface of the crystal is used as the object 4 to be measured.
(LN), a bimorph type piezoelectric actuator (manufactured by Sumitomo Metal Industries, Ltd.) was used as the vibrator 9. Vibrator 9 is given a vibration of frequency f (= 1 kHz) and amplitude λc / 2,
The reflected light (reference light) from the reference light mirror 6 is phase-modulated,
The reflected light (signal light) from the measuring object 4 and the reference light from the reference light mirror 6 were combined and interfered by the Si photodiode used as the light receiving element 10 to perform heterodyne detection. The detected detection signal is converted into a digital signal and
C to perform data processing, z3 (no) and z3 (n
e) (; the measurement sample scanning method) was specified, a known thickness t was given, and the birefringence of the X-cut LN was evaluated. In addition, 12
20 × and 5 × objective lenses are used for the lenses a and 12b, respectively. In addition, 20x objective lenses are used for the input and output ports of the light to the single mode optical fiber coupler, and the light entering the coupler is focused on the mode field diameter of the fiber, optimizing the coupling efficiency with the fiber. The emitted light is collimated into a 6 mmφ beam and guided to the condenser lens 3, the reference light mirror 6, and the lens 12b.

As a result, the optical path length z3 (1) (=
no × t) = 2388.2 μm, optical path length z3 in extraordinary light
(2) (= ne × t) = 2294.2 μm, and Δn × t =
| No-ne | × t = 94 μm. Since this measured value depends on the group refractive index ng, the group refractive index nog of ordinary light can be calculated from the thickness t = 1,028 μm measured with a micrometer.
2.3232, group refractive index ne g of the extraordinary light = 2.2317,
Δng = 0.0915 was obtained.

This result is based on the theoretical refractive index of the X-cut LN (nog =
2.3411, neg = 2.2497, Δng = 0.091
4), and the birefringence could be measured with an accuracy of less than 0.2%.

(Embodiment 5) In the present embodiment, the light of the xenon lamp is split into light source 1 in FIG. 12 by a monochromator (SM-3, manufactured by Spectrometer Co., Ltd.).
Light having a center wavelength λc = 850 nm was used. The full width at half maximum (FWHM) of this light spectrum was adjusted to Δλ = 24 nm as in the first embodiment. The coherence length of the interferometer determined by this is Δlc = 6.6 μm. Further, as the demultiplexing / combining means 2, a single mode fiber coupler,
0.1 μm / step linear motor stage (manufactured by Chuo Seiki Co., Ltd .: ALS902-H1L) as the driving means 7, and X-cut LiNbO 3 having the X axis of the crystal perpendicular to the plane as the object 4 to be measured
(LN), a bimorph type piezoelectric actuator (manufactured by Sumitomo Metal Industries, Ltd.) was used as the vibrator 9. The vibrator 9 is given a vibration of a frequency f (= 1 kHz) and an amplitude of λc / 2, and phase-modulates the reflected light (reference light) from the reference light mirror 6, using a Si photodiode used as the light receiving element 10.
The reflected light (signal light) from the measuring object 4 and the reference light mirror 6
Heterodyne detection was performed by multiplexing and interfering the reference light from.
The detected detection signal is converted into a digital signal, taken into a PC and subjected to data processing, and ΔL3 (no) and ΔL3 (n
e) (; reference light mirror scanning method) was specified, given a known thickness t, and the birefringence of the X-cut LN was evaluated. In addition, 12
20 × and 5 × objective lenses are used for the lenses a and 12b, respectively. In addition, 20x objective lenses are used for the input and output ports of the light to the single mode optical fiber coupler, and the light entering the coupler is focused on the mode field diameter of the fiber, optimizing the coupling efficiency with the fiber. The emitted light is collimated into a 6 mmφ beam and guided to the condenser lens 3, the reference light mirror 6, and the lens 12b.

As a result, the optical path length ΔL3 in ordinary light (1)
(= No × t) = 2388.1 μm, the optical path length in extraordinary light ΔL3 (2) (= ne × t) = 2293.9 μm, and Δn
× t = | no-ne | × t = 94.2 μm. Since this measured value depends on the group refractive index ng, the group refractive index n of ordinary light is obtained from the thickness t = 1,028 μm measured with a micrometer.
og = 2.3231, group refraction index of extraordinary light neg = 2.231
4. Δng = 0.0917 was obtained.

This result is based on the theoretical refractive index of the X-cut LN (nog =
2.3411, neg = 2.2497, Δng = 0.091
4), and the birefringence could be measured with an accuracy of less than 0.4%.

(Embodiment 6) In the present embodiment, the light source 1 shown in FIG.
m superluminescent diode (SLD) was used. The full width at half maximum (FWHM) of the spectrum of this SLD is Δλ
= 24 nm, and the determined coherence length of the interferometer is Δlc = 6.6 μm. A beam splitter (BS) and a condenser lens 3 are used as the demultiplexing / combining means 2.
, A 0.1 μm / step linear motor stage (ALS902-H1L, manufactured by Chuo Seiki Co., Ltd.) as the driving means 5 and 7, and a laminated piezoelectric actuator (Sumitomo Metal Industries, Ltd.) as the vibrator 9. Co., Ltd.) was used. The vibrator 9 has a frequency f (= 500 Hz) and an amplitude λc.
/ 2, the reflected light (reference light) from the reference light mirror 6 is phase-modulated, and the reflected light (signal light) from the object 4 and the reference light mirror are modulated by the Si photodiode used as the light receiving element 10. The reference light from No. 6 was multiplexed and interfered and heterodyne detected. The detected detection signal is converted into a digital signal, taken into a PC and processed for data, and ΔL
1, z1 (measurement sample scanning method) was specified. In addition, 12
20 × and 5 × objective lenses are used for the lenses a and 12b, respectively.

The NA (ζ) of the condenser lens 3 and the constants a and b
Used the value calibrated in the first embodiment.

As the object 4 to be measured, an ultraviolet-curable resin (manufactured by Kansai Paint Co., Ltd.) with a different amount of ultraviolet irradiation was measured. The same as the result of calculating the phase refractive index np and the thickness t by substituting the actually measured values of z1 and ΔL1 of the measuring object 4 at each ultraviolet irradiation amount into (Equation 13), (Equation 20), and (Equation 21). The results obtained by measuring the gel fraction of the sample (Table 4) and FIG.
FIG.

The conditions for measuring the gel fraction were as follows: reflux of methyl ethyl ketone: 2 hours, drying: 105 ° C. × 1 hour.

[0255]

[Table 4]

From the results, the cured state or degree of cure of the curable resin can be easily measured in a non-destructive and non-contact manner with a refractive index at an accuracy equal to or higher than the gel fraction of the conventional evaluation method. It turns out that it can be evaluated.

It is to be noted that the variation in each measurement point of the phase refractive index and the gel fraction in FIG. 18 is considered to be the variation in the sample preparation at each irradiation amount of ultraviolet rays.

The center wavelength of the light source and the full width at half maximum of the spectrum described above in the present embodiment are merely examples, and it is necessary to use a light source having similar performance and a light receiving element corresponding to the light source. Needless to say, it is possible.

The driving frequency and the like of the actuator are as follows.
It goes without saying that it is not limited.

Further, as described in the present embodiment,
The evaluation of the cured state or the degree of curing based on the refractive index of the ultraviolet curable resin is merely an example, and it goes without saying that evaluation of various curable resins can be performed.

In addition, in order to detect a signal of the light receiving element 10, the detection circuit 11 may include an amplification circuit, a filter, a sampling and holding circuit, and the like, if necessary. Further, the above-described filter operation may be performed by the PC 13.

[0262]

As described above, according to the present invention, a simple optical measurement system and detection signal processing by combining a low coherence interference optical system and a means for driving a reference light mirror, an object to be measured and a condenser lens are realized. It is possible to perform high-precision simultaneous measurement of phase refractive index and thickness of a measurement object, simultaneous measurement of birefringence and thickness, double refraction measurement, and simultaneous measurement of phase refractive index and group refractive index. In addition, in these simultaneous measurements, in order to irradiate the focused beam to the measurement object,
Simultaneous measurement of np (including birefringence) or ng (including birefringence) and t in a small area is possible, and np (including birefringence) by measuring the measurement object in a matrix
Alternatively, the spatial distribution of ng (including birefringence) and t can also be measured.

Further, by using the measuring method and measuring apparatus of the present invention, the cured state or degree of curing of the curable resin can be non-destructively, non-contacted, and easily equivalent to the gel fraction which is the conventional evaluation method. Alternatively, measurement and evaluation can be performed with higher accuracy.

[Brief description of the drawings]

FIG. 1 is a basic system configuration diagram of simultaneous measurement of phase refractive index and thickness, simultaneous measurement of phase refractive index and group refractive index according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a measurement sample scanning method and a lens scanning method according to an embodiment of the present invention.

FIG. 3 is an operation diagram of a reference light mirror in a measurement sample scanning method and a lens scanning method according to an embodiment of the present invention.

FIG. 4 is a principle diagram of a measurement sample scanning method according to an embodiment of the present invention.

FIG. 5 is a principle diagram of a lens scanning method according to an embodiment of the present invention.

FIG. 6 is a diagram showing a group of interference intensity patterns on a front surface and a rear surface detected by a measurement sample scanning method according to an embodiment of the present invention.

FIG. 7 is a diagram showing an example of the relationship between the wavelength dispersion and the phase refractive index of various measurement objects according to an embodiment of the present invention.

FIG. 8 is a diagram showing a group of interference intensity patterns on the front surface and the rear surface detected by the lens scanning method according to the embodiment of the present invention;

FIG. 9 is a diagram showing an example of determination of constants a and b according to an embodiment of the present invention.

FIG. 10 is a diagram showing an example of an interference signal detected by a measurement sample scanning method in birefringence measurement according to one embodiment of the present invention.

FIG. 11 is a diagram showing an example of an interference signal detected by a lens scanning method in birefringence measurement according to one embodiment of the present invention.

FIG. 12 is a basic system configuration diagram of birefringence measurement according to an embodiment of the present invention.

FIG. 13 is an explanatory diagram of a measurement sample scanning method and a reference light mirror scanning method in birefringence measurement according to one embodiment of the present invention.

FIG. 14 is an explanatory diagram of a measurement sample scanning method in birefringence measurement according to one embodiment of the present invention.

FIG. 15 is a diagram showing an example of an interference signal detected by a measurement sample scanning method in birefringence measurement according to one embodiment of the present invention.

FIG. 16 is an explanatory diagram of a reference light mirror scanning method in birefringence measurement according to one embodiment of the present invention.

FIG. 17 is a diagram showing an example of an interference signal detected by a reference light mirror scanning method in birefringence measurement according to one embodiment of the present invention.

FIG. 18 is a diagram showing the relationship between the phase refractive index and the gel fraction of the ultraviolet-curable resin and the amount of ultraviolet irradiation according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Demultiplexing / combining means 3 Condensing lens 4 Object to be measured 5 Driving means 6 Reference light mirror 7 Driving means 8 Driving means 9 Transducer 10 Light receiving element 11 Detection circuit 12a Lens 12b Lens 13 Personal computer (PC) 14 Stage controller

Claims (61)

[Claims] 1. A driving means for holding and mounting an object to be measured or a condensing lens and a reference light mirror, a light source, and multiplexing / interference of reflected light from the object to be measured and reference light from the reference light mirror. An interference optical system including a light receiving element for detecting the light, the light from the light source of the interference optical system is condensed by the condensing lens to irradiate the measurement object, the reference light mirror and the reference light mirror The measurement object or the condenser lens and the reference light mirror are moved so that the interference light intensity on the front surface and the rear surface of the measurement object are respectively maximized, and a position where the interference light maximum intensity appears on the front surface,
By calculating the moving distance of the measuring object or the condensing lens and the reference light mirror at the position of the maximum intensity of the interference light on the rear surface, the refractive index and the thickness of the measuring object are simultaneously measured. How to measure the medium. 2. A driving means for holding and mounting an object to be measured and a reference light mirror, a light source, a condenser lens held by the holding means, a light reflected from the object to be measured and a reference from the reference light mirror. A light receiving element for multiplexing / interfering light and detecting the light, wherein the light from the light source of the interference optical system is condensed by the condensing lens and irradiated to the object to be measured. Move the measurement object and the reference light mirror so that the interference light intensity on the front and back surfaces of the reference light mirror and the measurement object are respectively maximum, and the position where the interference light maximum intensity on the front surface appears. Measuring the refractive index and the thickness of the measurement object at the same time by determining the moving distance of the measurement object and the reference light mirror at the position of the maximum intensity of the interference light on the rear surface. Method. 3. A driving means for holding and mounting a condenser lens and a reference light mirror, a light source, a measurement object held by the holding means, a reflected light from the measurement object and a reference from the reference light mirror. A light receiving element for detecting light by multiplexing and interfering light, wherein the light from the light source of the interference optical system is condensed by the condensing lens on the object to be measured and the measurement is performed. By irradiating the object, the converging lens and the reference light mirror are moved so that the interference light intensity on the front surface and the rear surface of the reference light mirror and the front surface and the rear surface of the measurement object are maximized, and the interference light maximum intensity on the front surface The position where appears, and by determining the moving distance of the measurement object and the reference light mirror at the position of the maximum interference light intensity on the rear surface, simultaneously measuring the refractive index and thickness of the measurement object. You Method of measuring the medium. 4. A driving means for holding and mounting an object to be measured or a reference light mirror, a light source, and a light receiving means for detecting reflected light by multiplexing / interfering reflected light from the object to be measured and reference light from the reference light mirror. A light from the light source of the interference optical system, and irradiates the measurement object with the interference light intensity on the front surface of the reference light mirror and the measurement object and the interference light intensity on the rear surface of the measurement object. The target object or the reference light mirror is moved so that the two interference light intensities corresponding to the light beam and the extraordinary light beam are respectively maximized, the position where the interference light maximum intensity appears on the front surface, and the ordinary light beam on the rear surface. The birefringence of the measurement object is measured by obtaining the moving distance of the measurement object or the reference light mirror at the position of the two interference light maximum intensities corresponding to the extraordinary rays. Method of measuring the medium. 5. A driving means for holding and mounting an object to be measured, a light source, a reference light mirror held by the holding means, and a multiplexed light reflected from the object to be measured and a reference light from the reference light mirror. An interference optical system including a light-receiving element for detecting interference and irradiating the measurement object with light from the light source of the interference optical system, and a reference light mirror held by holding means and the reference light mirror; The position where the interference light intensity on the front surface and the interference light intensity on the rear surface are moved so that the two interference light intensities corresponding to the ordinary ray and the extraordinary ray respectively become maximum, and the interference light maximum intensity on the front face appears And a medium measuring method characterized by measuring a birefringence of the object to be measured by determining a difference in a moving distance between two positions of the maximum intensity of the interference light corresponding to the ordinary ray and the extraordinary ray on the rear surface. 6. A driving means for holding and mounting a reference light mirror,
A light source, an object to be measured held by holding means, and an interference optical system including a light-receiving element for detecting by combining and interfering reflected light from the object to be measured and reference light from the reference light mirror. And irradiating the object to be measured with light from the light source of the interference optical system so as to correspond to the intensity of the interference light on the front surface of the reference light mirror and the object to be measured and the ordinary and extraordinary rays on the rear surface. The reference light mirror is moved so that each of the two interference light intensities becomes maximum, and the position of the interference light maximum intensity on the front surface and the position of the two interference light maximum intensity corresponding to the ordinary ray and the extraordinary ray on the rear face A method for measuring a medium, comprising: measuring a birefringence of the object to be measured by calculating a difference in a moving distance. 7. A driving means for holding and mounting an object to be measured or a condenser lens and a reference light mirror, a light source, and multiplexing / interfering of reflected light from the object to be measured and reference light from the reference light mirror. An interference optical system including a light receiving element for detecting the light, the light from the light source of the interference optical system is condensed by the condensing lens to irradiate the measurement object, the reference light mirror and the reference light mirror Move the measurement object or the condenser lens and the reference light mirror so that the interference light intensity on the front surface of the measurement object and the two interference light intensity corresponding to the ordinary ray and the extraordinary ray on the rear surface are respectively maximized. The position where the maximum intensity of the interference light on the front surface appears,
By determining the moving distance of the measurement object or the condensing lens and the reference light mirror at the position of the two interference light maximum intensities corresponding to the ordinary ray and the extraordinary ray on the rear surface,
A method for measuring a medium, comprising simultaneously measuring a birefringence and a thickness of the object to be measured. 8. A driving means for holding and mounting a measurement object and a reference light mirror, a light source, a condenser lens, and multiplexing / interference of reflected light from the measurement object and reference light from the reference light mirror. A light receiving element for detecting and detecting, the light from the light source of the interference optical system is condensed by the condensing lens to irradiate the measurement object, the reference light mirror and The measurement object and the reference light mirror are moved so that the interference light intensity on the front surface of the measurement object and the two interference light intensity corresponding to the ordinary ray and the extraordinary ray on the rear surface are maximized, respectively. By finding the difference between the position where the light maximum intensity appears and the moving distance of the measurement object and the reference light mirror at the position of the two interference light maximum intensities corresponding to the ordinary ray and the extraordinary ray on the rear surface, Measuring method of the medium, characterized by simultaneously measuring the birefringence and thickness of the constant object. 9. A driving means for holding and mounting a condenser lens and a reference light mirror, a light source, a measurement object held by the holding means, a reflected light from the measurement object and a reference from the reference light mirror. A light receiving element for detecting light by multiplexing and interfering light, wherein the light from the light source of the interference optical system is condensed by the condensing lens on the object to be measured and the measurement is performed. Irradiate the target object, so that the interference light intensity on the front surface of the reference light mirror and the measurement object and the two interference light intensity corresponding to the ordinary ray and the extraordinary ray on the rear face are respectively maximized, the condensing lens and The reference light mirror is moved, the measurement object and the reference light mirror at the position where the maximum intensity of the interference light appears on the front surface and at the position of the two maximum intensity of the interference light corresponding to the ordinary ray and the extraordinary ray on the rear surface. By obtaining the difference between the moving distance of the measuring method of the medium, characterized by simultaneously measuring the birefringence and thickness of the measurement object. 10. A driving means for holding and mounting an object to be measured or a condenser lens and a reference light mirror, a light source, and multiplexing / interference of reflected light from the object to be measured and reference light from the reference light mirror. An interference optical system including a light receiving element for detecting the light, the light from the light source of the interference optical system is condensed by the condensing lens to irradiate the measurement object, the reference light mirror and the reference light mirror The measurement object or the condenser lens and the reference light mirror are moved so that the interference light intensity on the front surface and the rear surface of the measurement object are respectively maximized, and the position where the interference light maximum intensity appears on the front surface and the rear surface The phase refractive index and the group refractive index of the measurement object are simultaneously determined by calculating the moving distance of the measurement object or the condenser lens and the reference light mirror at the position of the maximum intensity of the interference light in Measuring method of the medium, characterized by a constant. 11. A driving means for holding and mounting a measurement object and a reference light mirror, a light source, a condenser lens held by the holding means, a reflected light from the measurement object and a reference from the reference light mirror. A light receiving element for multiplexing / interfering light and detecting the light, wherein the light from the light source of the interference optical system is condensed by the condensing lens and irradiated to the object to be measured. Move the measurement object and the reference light mirror so that the interference light intensity on the front and back surfaces of the reference light mirror and the measurement object are respectively maximum, and the position where the interference light maximum intensity on the front surface appears. Determining the moving distance of the measurement object and the reference light mirror at the position of the maximum intensity of the interference light on the rear surface, thereby simultaneously measuring the phase refractive index and the group refractive index of the measurement object. The measurement method of the medium. 12. A driving means for holding and mounting a condenser lens and a reference light mirror, a light source, a measurement object held by the holding means, light reflected from the measurement object and reference from the reference light mirror. A light receiving element for detecting light by multiplexing and interfering light, wherein the light from the light source of the interference optical system is condensed by the condensing lens on the object to be measured and the measurement is performed. By irradiating the object, the converging lens and the reference light mirror are moved so that the interference light intensity on the front surface and the rear surface of the reference light mirror and the front surface and the rear surface of the measurement object are maximized, and the interference light maximum intensity on the front surface Is obtained, and the phase refractive index and the group refractive index of the measurement object are measured simultaneously by determining the moving distance of the measurement object and the reference light mirror at the position of the maximum intensity of the interference light on the rear surface. Measuring method of the medium, characterized and. 13. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and a second light split by the light splitting means. Means for irradiating the object to be measured with a condenser lens, driving means for holding and mounting the object to be measured or the condenser lens and the reference light mirror for minute movement, reflected light from the object to be measured and the reference A medium measuring device for simultaneously measuring a refractive index and a thickness of an object to be measured by an interference optical system including a light receiving element for detecting a reference light from a light mirror by multiplexing / interfering the light. 14. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and a second light splitting means for splitting the other light split by the light splitting means. Means for irradiating the object to be measured by a condenser lens, driving means for holding and mounting the object to be measured and the reference light mirror for fine movement, reflected light from the object to be measured and reference from the reference light mirror An apparatus for measuring a medium, wherein a refractive index and a thickness of an object to be measured are simultaneously measured by an interference optical system having a light receiving element for detecting light by multiplexing / interfering light. 15. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and a second light splitting means for splitting the other light split by the light splitting means. Means for irradiating the object to be measured with a condensing lens, driving means for holding and mounting the condensing lens and the reference light mirror for fine movement, reflected light from the object to be measured, and reference light from the reference light mirror A measuring device for measuring the refractive index and the thickness of the object to be measured simultaneously by an interference optical system having a light receiving element for detecting by multiplexing / interfering light. 16. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and another light splitting means for splitting the light by the light splitting means. Means for irradiating the object to be measured, driving means for holding and mounting the object to be measured or the reference light mirror for fine movement, and multiplexing reflected light from the object to be measured and reference light from the reference light mirror A medium measuring device for measuring the birefringence of the object to be measured by an interference optical system having a light receiving element for detecting by interference. 17. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and another light splitting means for splitting the light by the light splitting means. Means for irradiating the object to be measured, driving means for holding and mounting the object to be measured and slightly moving, and detecting and detecting light by multiplexing / interfering reflected light from the object to be measured and reference light from the reference light mirror. A medium for measuring the birefringence of the object to be measured by an interference optical system having a light receiving element that performs the measurement. 18. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and another light splitting means for splitting the light by the means for splitting light. Means for irradiating the object to be measured, driving means for holding and mounting the reference light mirror for fine movement, and detection by multiplexing / interfering the reflected light from the object to be measured and the reference light from the reference light mirror A medium for measuring the birefringence of the object to be measured by an interference optical system having a light receiving element that performs the measurement. 19. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and another light splitting means for splitting the light by the light splitting means. Means for irradiating the object to be measured with a condenser lens, driving means for holding and mounting the object to be measured or the condenser lens and the reference light mirror for minute movement, reflected light from the object to be measured and the reference A medium measuring device for simultaneously measuring the birefringence and the thickness of an object to be measured by an interference optical system including a light receiving element for detecting a reference beam from a light mirror by multiplexing / interfering the reference beam. 20. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and a second light splitting means for splitting the light by the means for splitting light. Means for irradiating the object to be measured by a condenser lens, driving means for holding and mounting the object to be measured and the reference light mirror for fine movement, reflected light from the object to be measured and reference from the reference light mirror An apparatus for measuring a medium, wherein the birefringence and the thickness of the object to be measured are simultaneously measured by an interference optical system including a light receiving element for detecting light by multiplexing / interfering light. 21. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and another light split by the means for splitting light. Means for irradiating the object to be measured with a condensing lens, driving means for holding and mounting the condensing lens and the reference light mirror for fine movement, reflected light from the object to be measured, and reference light from the reference light mirror A measuring device for measuring the birefringence and the thickness of the object to be measured simultaneously by an interference optical system having a light receiving element for detecting by multiplexing / interfering light. 22. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and a second light splitting means for splitting the other light split by the light splitting means. Means for irradiating the object to be measured with a condenser lens, driving means for holding and mounting the object to be measured or the condenser lens and the reference light mirror for minute movement, reflected light from the object to be measured and the reference A medium measuring device for simultaneously measuring a phase refractive index and a group refractive index of the object to be measured by an interference optical system having a light receiving element for detecting and multiplexing / interfering a reference light from an optical mirror. . 23. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and another light split by the means for splitting light. Means for irradiating the object to be measured by a condenser lens, driving means for holding and mounting the object to be measured and the reference light mirror for fine movement, reflected light from the object to be measured and reference from the reference light mirror A medium measuring device for simultaneously measuring a phase refractive index and a group refractive index of an object to be measured by an interference optical system including a light receiving element for detecting light by multiplexing / interfering light. 24. A light source, means for splitting light from the light source, a reference light mirror for receiving and reflecting one light split by the light splitting means, and a second light split by the light splitting means. Means for irradiating the object to be measured with a condensing lens, driving means for holding and mounting the condensing lens and the reference light mirror for fine movement, reflected light from the object to be measured, and reference light from the reference light mirror A measuring apparatus for measuring a phase refractive index and a group refractive index of the object to be measured simultaneously by an interference optical system including a light receiving element for detecting and multiplexing and interfering the light. 25. The simultaneous measurement of the refractive index and the thickness is performed by using a calculation formula in consideration of the wavelength dispersion of the refractive index of the object to be measured.
The method for measuring a medium according to claim 1, wherein a phase refractive index and a thickness of the object to be measured are derived at the same time. 26. The simultaneous measurement of the birefringence and the thickness is performed by using a calculation formula taking into consideration the wavelength dispersion of the refractive index of the object to be measured.
The method for measuring a medium according to claim 7, wherein a phase refractive index and a thickness of the measurement object are derived at the same time. 27. The light source according to claim 1, wherein the light source emits low coherence light.
The method for measuring a medium according to any one of 0 to 12. 28. The light source according to claim 4, wherein the light source emits low coherence light.
The method for measuring the medium described. 29. The method for measuring a medium according to claim 27, wherein the light source for emitting the low coherence light is a linearly polarized light, a non-polarized light or a random polarized light. 30. The method for measuring a medium according to claim 28, wherein the light source that emits the low coherence light is an unpolarized light or a randomly polarized light. 31. A light source that emits the low coherence light has a coherence length ΔLc (= ((ln (2)) × (2 /
31. The method for measuring a medium according to claim 29, wherein (π) × (λc ² / △ λ)) / 2) is 30 μm or less. 32. The medium measuring method according to claim 31, wherein the light source emitting the low coherence light is a superluminescent diode. 33. The medium measuring method according to claim 31, wherein the light source for emitting the low coherence light is a light source obtained by dispersing light from a white light source in a specific wavelength range by a monochromator. 34. The medium measuring apparatus according to claim 1, wherein the interference optical system includes a unit for demultiplexing and combining light from the light source as one of the components. Method. 35. The driving means for holding and mounting the object to be measured, the reference light mirror and the condenser lens is a fine movement stage.
The method for measuring the medium described. 36. The reference light mirror according to claim 1, wherein the reference light mirror is fixed to a vibrator for vibrating the reference light mirror to phase-modulate the reference light in the interference optical system. 2. The method for measuring a medium according to 1. 37. The medium measuring method according to claim 36, wherein the phase modulation of the reference light is performed by applying a vibration having an amplitude of λc / 2 or less of an oscillation center wavelength λc of the light source and a frequency of 100 Hz or more. 38. The light receiving element according to claim 1, wherein said light receiving element is a photodiode for heterodyne detection.
A method for measuring a medium according to any one of the preceding claims. 39. The medium measuring method according to claim 1, wherein the heterodyne-detected detection signal is converted into a digital signal by a detection circuit and processed. 40. The object according to claim 1, wherein the object to be measured is a medium that does not completely absorb light from the light source.
13. The method for measuring a medium according to any one of items 12 to 12. 41. The method for measuring a medium according to claim 1, wherein the object to be measured is a living tissue. 42. The simultaneous measurement of the refractive index and the thickness is performed by using a calculation formula in consideration of the wavelength dispersion of the refractive index of the object to be measured.
The medium measuring apparatus according to claim 13, wherein a phase refractive index and a thickness of the measurement object are derived at the same time. 43. The simultaneous measurement of the birefringence and the thickness is performed by using a calculation formula in consideration of the wavelength dispersion of the refractive index of the object to be measured.
22. The medium measuring device according to claim 19, wherein a phase refractive index and a thickness of the object to be measured are derived at the same time. 44. An apparatus according to claim 13, wherein said light source is a light source for emitting low coherence light. 45. A medium measuring apparatus according to claim 16, wherein said light source is a light source for emitting low coherence light. 46. The medium measuring apparatus according to claim 44, wherein the light source for emitting the low coherence light is a linearly polarized light, a non-polarized light, or a randomly polarized light source. 47. The medium measuring apparatus according to claim 45, wherein the light source for emitting the low coherence light is a non-polarized or randomly polarized light source. 48. A light source which emits the low coherence light has a coherence length ΔLc (= ((ln (2)) × (2 /
48. The medium measuring apparatus according to claim 46, wherein (π) × (λc ² / △ λ)) / 2) is 30 μm or less. 49. The medium measuring apparatus according to claim 48, wherein the light source for emitting the low coherence light is a superluminescent diode. 50. The medium measuring apparatus according to claim 48, wherein the light source that emits the low coherence light is a light source obtained by separating light from a white light source into a specific wavelength by a monochromator. 51. A medium measuring apparatus according to claim 13, wherein said interference optical system includes means for demultiplexing and combining light from said light source as one of the components. apparatus. 52. A medium measuring apparatus according to claim 13, wherein said driving means for holding and mounting said object to be measured, said reference light mirror and said condenser lens is a fine movement stage. . 53. The reference light mirror according to claim 13, wherein the reference light mirror is fixed to a vibrator that vibrates the reference light mirror to phase-modulate the reference light in the interference optical system. 2. The medium measuring device according to 1. 54. The medium measuring apparatus according to claim 53, wherein the phase modulation of the reference light is performed by applying a vibration whose amplitude is not more than λc / 2 of the oscillation center wavelength λc of the light source and whose frequency is not less than 100 Hz. 55. The light receiving element according to claim 13, wherein said light receiving element is a photodiode for heterodyne detection.
4. The apparatus for measuring a medium according to any one of 4 above. 56. The medium measuring apparatus according to claim 13, wherein said detection signal subjected to heterodyne detection is converted into a digital signal by a detection circuit and processed. 57. An object according to claim 1, wherein said object to be measured is a medium which does not completely absorb light from said light source.
25. The apparatus for measuring a medium according to any one of 3 to 24. 58. The medium measuring apparatus according to claim 13, wherein the object to be measured is a living tissue. 59. A method for measuring a medium, comprising: measuring a refractive index averaged in a thickness direction of a curable resin; and evaluating a cured state or a degree of curing of the curable resin using the index as an index. 60. A method for measuring a medium, wherein the refractive index of the curable resin is measured by the method according to any one of claims 1 to 3. 61. A method for measuring a medium, wherein the refractive index of the curable resin is measured by the measuring device according to any one of claims 13 to 15.