WO2012118079A1 - 光学特性測定装置及び光学特性測定方法 - Google Patents
光学特性測定装置及び光学特性測定方法 Download PDFInfo
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- WO2012118079A1 WO2012118079A1 PCT/JP2012/054940 JP2012054940W WO2012118079A1 WO 2012118079 A1 WO2012118079 A1 WO 2012118079A1 JP 2012054940 W JP2012054940 W JP 2012054940W WO 2012118079 A1 WO2012118079 A1 WO 2012118079A1
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- 230000003287 optical effect Effects 0.000 title claims abstract description 157
- 238000000034 method Methods 0.000 title claims description 12
- 238000003384 imaging method Methods 0.000 claims abstract description 70
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- 230000004907 flux Effects 0.000 abstract description 11
- 230000010363 phase shift Effects 0.000 description 12
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/21—Polarisation-affecting properties
- G01N21/23—Bi-refringence
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
- G01J3/0224—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows using polarising or depolarising elements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J3/45—Interferometric spectrometry
- G01J3/453—Interferometric spectrometry by correlation of the amplitudes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J3/45—Interferometric spectrometry
- G01J3/453—Interferometric spectrometry by correlation of the amplitudes
- G01J3/4535—Devices with moving mirror
Definitions
- the present invention relates to an optical property measuring apparatus and method capable of measuring both the spectral property and polarization property of a substance.
- a method for estimating an unknown component in a substance by measuring the optical characteristics of the substance is known.
- a birefringence phase difference (retardation) is obtained from transmitted light intensity when light is transmitted through a substance to be measured, and a substance-specific birefringence is calculated from the birefringence phase difference.
- Birefringence refers to a phenomenon in which two refracted lights appear when light enters an anisotropic medium.
- the birefringence phase difference is expressed by the product of the birefringence and the transmitted optical path length, even if the birefringence phase difference is the same, the birefringence is different if the transmitted optical path length of light is different. Therefore, an accurate birefringence can be obtained by using a transmission optical path length accurately determined with respect to the measured birefringence phase difference.
- the transmission optical path length cannot be easily obtained in the measurement object, for example, when the shape of the measurement object is complicated, it is difficult to obtain an accurate birefringence.
- the measurement target is a biological membrane such as an eye retina, the measurement target cannot be cut out from the human body, and thus the thickness, that is, the transmitted optical path length cannot be measured.
- birefringence is an optical property observed when a material is an anisotropic medium, so when estimating the components of an unknown material, both birefringence and Fourier spectroscopic properties are measured. It is effective to do.
- the conventional apparatus cannot measure both the Fourier spectral characteristics and the birefringence at the same time.
- the problem to be solved by the present invention is to provide an optical characteristic measuring apparatus and an optical characteristic measuring method capable of simultaneously measuring Fourier spectral characteristics and birefringence of substances having various shapes and properties.
- An optical property measuring apparatus which has been made to solve the above problems, a) a splitting optical system that guides light emitted from the measurement object to which linearly polarized light is incident to the first polarizing plate and the second polarizing plate; b) an analyzer that transmits light in a predetermined polarization direction out of a combined component of the first polarization component transmitted through the first polarizing plate and the second polarization component transmitted through the second polarizing plate; c) an imaging optical system for guiding the light transmitted through the analyzer to the same point to form an interference image; d) a detection unit for detecting the light intensity of the interference image; e) By changing a difference in optical path length between the first polarization component and the second polarization component from the first polarization plate and the second polarization plate toward the analyzer, the difference between the first polarization component and the second polarization component is obtained.
- a phase difference providing means for changing the phase difference f) Processing for obtaining an amplitude and a birefringence phase difference for each wavelength of light emitted from the object to be measured by Fourier-transforming data on the change in light intensity detected by the detection unit with the change in the phase difference And a section.
- the optical property measuring apparatus is a) a splitting optical system that guides light emitted from the measurement object to which linearly polarized light is incident to the first polarizing plate and the second polarizing plate; b) an analyzer that transmits light in a predetermined polarization direction out of a combined component of the first polarized light component transmitted through the first polarizing plate and the second polarized light component transmitted through the second polarizing plate; c) an imaging optical system for condensing the light transmitted through the analyzer on the same straight line extending in a direction different from the optical axes of the first polarization component and the second polarization component to form a linear interference image; , d) By giving a continuous optical path length difference distribution between the first polarization component and the second polarization component from the first polarization plate and the second polarization plate toward the analyzer, the first polarization component and the second polarization Phase change applying means for giving a continuous phase change between the components; e) a detection optical path length difference distribution between the
- the optical characteristic measuring device is a) a splitting optical system that guides light emitted from the measurement object to which linearly polarized light is incident to the first polarizing plate and the second polarizing plate; b) an analyzer that transmits light in a predetermined polarization direction out of a combined component of the first polarization component transmitted through the first polarizing plate and the second polarization component transmitted through the second polarizing plate; c) an imaging optical system for condensing the light transmitted through the analyzer on the same straight line extending in a direction different from the optical axes of the first polarization component and the second polarization component to form a linear interference image; , d) By giving a continuous optical path length difference distribution between the first polarization component and the second polarization component from the first polarization plate and the second polarization plate toward the analyzer, the first polarization component and the second polarization Phase change applying means for giving a continuous phase change between the components; e) a spectral optical system that guides light e
- the first polarization component and the linear polarization electric field component incident on the object to be measured are orthogonal to each other.
- the first polarizing plate and the second polarizing plate are preferably arranged so that the polarization direction of the second polarizing component is inclined by 45 °.
- the splitting optical system includes an objective lens that converts the light emitted from the object to be measured into parallel rays and guides the light to the first polarizing plate and the second polarizing plate,
- the processing unit may obtain an amplitude and a birefringence phase difference (phase difference amount) for each wavelength of light emitted from a focal point of the objective lens in the object to be measured.
- a focusing position changing unit that relatively changes a focusing position of the objective lens with respect to the object to be measured is provided.
- the optical property measuring method includes: a) Make linearly polarized light incident on the object to be measured, b) The light emitted from the object to be measured on which the linearly polarized light is incident is guided to the first polarizing plate and the second polarizing plate by the splitting optical system, c) The first polarized light component transmitted through the first polarizing plate and the second polarized light component transmitted through the second polarizing plate are detected while changing a difference in optical path length between the first polarized light component and the second polarized light component.
- the imaging optical system In addition to being guided to the imaging optical system via photons, the imaging optical system focuses the light at the same point to form an interference image, d) The amplitude and the birefringence phase difference of each wavelength of the light emitted from the object to be measured are obtained by performing Fourier transform on the data indicating the change in the light intensity of the interference image.
- the optical property measurement method includes: a) Make linearly polarized light incident on the object to be measured, b) The light emitted from the object to be measured on which the linearly polarized light is incident is guided to the first polarizing plate and the second polarizing plate by the splitting optical system, c) The first polarization component transmitted through the first polarizing plate and the second polarization component transmitted through the second polarizing plate have a continuous optical path length difference distribution between the first polarization component and the second polarization component.
- the imaging optical system While being guided to the imaging optical system through the analyzer, the imaging optical system collects light on the same straight line to form a linear interference image, d) Obtaining the amplitude and birefringence phase difference of each wavelength of the light emitted from the object to be measured by Fourier transforming the data indicating the light intensity distribution along the direction in which the interference image extends in the linear interference image. It is characterized by doing.
- the optical property measuring method is: a) Make linearly polarized light incident on the object to be measured, b) The light emitted from the object to be measured on which the linearly polarized light is incident is guided to the first polarizing plate and the second polarizing plate by the splitting optical system, c) The first polarization component transmitted through the first polarizing plate and the second polarization component transmitted through the second polarizing plate have a continuous optical path length difference distribution between the first polarization component and the second polarization component.
- the imaging optical system While being guided to the imaging optical system through the analyzer, the imaging optical system collects light on the same straight line to form a linear interference image, d) A spectral spectrum is obtained by wavelength-resolving the linear interference image by a spectral optical system, e) obtaining an amplitude and a birefringence phase difference of each wavelength of light emitted from the object to be measured based on a light intensity distribution of the spectrum.
- the light emitted from the measurement object on which the linearly polarized light is incident is guided to the first polarizing plate and the second polarizing plate by the splitting optical system, and the first polarized light After passing through the plate and the second polarizing plate, it enters the analyzer as a first polarization component and a second polarization component.
- the light transmitted through the analyzer is guided to the same point or the same straight line by the imaging optical system to form an interference image.
- the phase difference between the first polarization component and the second polarization component is changed temporally or spatially, the intensity of the interference light detected by the detection unit changes, and the synthesis is similar to an interferogram.
- a waveform is acquired.
- the processing unit When the composite waveform is Fourier transformed by the processing unit, the amplitude and the birefringence phase difference of each wavelength of the light emitted from the object to be measured are obtained, so that the Fourier spectral characteristics and the birefringence of the object to be measured are simultaneously obtained. Can be sought. In the case where two lights are guided to the same “point” and interfere with each other, strictly speaking, it is not “interference image” but “interference light”, but here it is formed by the interference of the two lights. All of them are called “interference images”.
- the Fourier spectral characteristics and the birefringence of the object to be measured using the light. Sex can be determined at the same time. Therefore, not only products with relatively simple shapes such as optical elements and polymer films, but also substances with complicated shapes and biological membranes such as the retina of the eye can be measured objects, so that they can be used in a wide range of fields.
- the light emitted from the object to be measured is separated into two parts using a Michelson interferometer, and the two parts are separated.
- the light is guided to a common optical path to cause interference, and the interference light is detected by a detector. Since the light separated into two interferes on the common optical path, interference light of light emitted from various positions (depths) of the object to be measured is mixed on the light receiving surface of the detector.
- the light emitted from the object to be measured is divided into the first polarization component and the second polarization component by the splitting optical system, and these polarization components are directed to the imaging optical system through separate optical paths.
- the imaging optical system guides to the same point to cause interference. Since only the light emitted from the focusing surface interferes on the imaging surface of the imaging optical system, in the present invention, by positioning the light receiving surface of the detection unit on the imaging surface of the imaging optical system, Only the part of the object to be measured that corresponds to the focal plane, that is, the interference light of the light emitted from a specific depth in the object to be measured can be detected by the detector, and a clear interference image with little noise can be obtained. Obtainable.
- FIG. 2 is a diagram for explaining the measurement principle of the optical characteristic measuring apparatus according to the first embodiment, and shows a linearly polarized light component and an electric field component obtained by vector decomposition of the linearly polarized light component into orthogonal components in the x direction and the y direction;
- FIG. A diagram showing a combined vector when there is a phase difference of ⁇ / 2 between the electric field component in the x direction and the y direction, and the electric field component and the combined vector in the x and y directions viewed from the light traveling direction.
- FIG. The figure (a) which shows the composite vector when giving the phase difference which cancels the unknown birefringence phase difference (retardation) given by the measuring object between the electric field component of x direction and y direction, and these x and y directions (B) which looked at the electric field component and synthetic
- the figure which shows the relationship between phase shift amount and imaging intensity.
- FIG. 5 is a diagram showing a schematic overall configuration of an optical characteristic measuring apparatus according to Embodiment 2 of the present invention.
- FIG. 5 is a diagram showing a schematic overall configuration of an optical characteristic measuring apparatus according to Embodiment 2 of the present invention.
- FIG. 10 is a diagram illustrating an arrangement of optical elements from a measurement target to an imaging plane in the optical characteristic measurement apparatus according to the second embodiment.
- FIG. 6 is a side view illustrating a state in which measurement light is collected on a light receiving surface by an imaging lens in the second embodiment.
- FIG. 6 is a top view illustrating a state in which measurement light is collected on a light receiving surface by an imaging lens in the second embodiment.
- FIG. 6 is a diagram illustrating a schematic overall configuration of an optical characteristic measuring apparatus according to Embodiment 3 of the present invention.
- FIG. 6 is a perspective view of an imaging lens in Embodiment 3.
- FIG. 10 is a diagram illustrating an interference image of a reference light beam and an inclined light beam in Example 3.
- FIG. 6 is a diagram illustrating a schematic overall configuration of an optical characteristic measuring apparatus according to Embodiment 4 of the present invention.
- the optical characteristic measuring apparatus 1 includes a light source 3, a polarizer 5, an objective lens 7, a first polarizing plate 9 and a second polarizing plate 11, a phase shifter 13, and an analyzer 15.
- An imaging lens 17 and a detector 19 In this embodiment, the objective lens 7, the first polarizing plate 9, and the second polarizing plate 11 constitute a split optical system, and the imaging lens 17 constitutes an imaging optical system.
- the phase shifter 13 functions as a phase difference providing unit.
- the objective lens 7 is configured to be movable in the optical axis direction by the lens driving mechanism 21.
- the lens driving mechanism 21 is for scanning the focus position of the objective lens 7 and corresponds to a focus position changing unit.
- the lens driving mechanism 21 can be constituted by a piezo element, for example.
- the polarizer 5 is disposed on the optical path of the light emitted from the light source 3, extracts only the linearly polarized light component in a specific direction from the light, and irradiates the sample S that is the object to be measured.
- the light transmitted through the sample S (hereinafter also referred to as “measurement light”) enters the objective lens 7 and is converted into a parallel light beam.
- 1 and 2 show a transmissive optical characteristic measuring apparatus 1 that measures light transmitted through the sample S.
- a reflective optical characteristic measurement that measures light reflected from the inside of the sample S is shown. It may be a device. This is because both the light transmitted through the sample and the light reflected inside the sample have the birefringence and light absorption characteristics of the components in the sample.
- the light beam after passing through the objective lens 7 does not have to be a perfect parallel light beam. As will be described later, it is sufficient that the measurement light can be expanded to such a degree that it can be divided into two or more. However, if the light beam is not a parallel light beam, an error is likely to occur in the phase difference amount generated according to the phase shift amount described later. Therefore, in order to obtain higher measurement accuracy, it is desirable to use a parallel beam as much as possible.
- Both the first polarizing plate 9 and the second polarizing plate 11 are arranged, for example, vertically on the optical path of the parallel light flux that has passed through the objective lens 7.
- the parallel light beam that has passed through the objective lens 7 reaches the phase shifter 13 via the first polarizing plate 9 and the second polarizing plate 11.
- the first polarizing plate 9 and the second polarizing plate 11 have their polarization directions inclined by 45 ° with respect to the vibration direction of the electric field vector of the linearly polarized light component transmitted through the polarizer 5, and
- the polarizing direction of the first polarizing plate 9 and the polarizing direction of the second polarizing plate 11 are installed so as to be orthogonal to each other.
- the polarization direction of the first polarizing plate 9 is also referred to as the x direction
- the polarization direction of the second polarizing plate 11 is also referred to as the y direction.
- the light transmitted through the first polarizing plate 9 is referred to as first polarized light
- the light transmitted through the second polarizing plate 11 is referred to as second polarized light.
- the phase shifter 13 includes a rectangular plate-shaped movable mirror unit 131, a rectangular plate-shaped fixed mirror unit 132 disposed under the rectangular plate-shaped movable mirror unit 131, holding units 133 and 134 that hold the movable mirror unit 131 and the fixed mirror unit 132, and a movable mirror unit.
- a drive stage 135 that moves the holding unit 133 of 131 is provided.
- the first polarized light transmitted through the first polarizing plate 9 enters the movable mirror unit 131, and the second polarized light transmitted through the second polarizing plate 11 enters the fixed mirror unit 132.
- the surfaces (reflection surfaces) of the movable mirror unit 131 and the fixed mirror unit 132 are optically flat and are optical mirror surfaces that can reflect the wavelength band of light to be measured by the apparatus 1. Further, the reflecting surfaces of the movable mirror part 131 and the fixed mirror part 132 have substantially the same size.
- the light beam that reaches the reflecting surface of the movable mirror unit 131 from the first polarizing plate 9 and is reflected and reaches the analyzer 15 is moved to the moving light beam, and the reflecting surface of the fixed mirror unit 132 from the second polarizing plate 11.
- the light beam that reaches and is reflected and reaches the analyzer 15 is also referred to as a fixed light beam.
- the drive stage 135 is composed of, for example, a piezoelectric element having a capacitance sensor, and moves the holding unit 133 in the direction of arrow A in response to a control signal from the control unit 25.
- the movable mirror part 131 moves in the arrow A direction with an accuracy according to the wavelength of light.
- the phase shifter 13 corresponds to the optical path length difference expansion / contraction means
- the movable mirror part 131 and the fixed mirror part 132 correspond to the first reflection part and the second reflection part, respectively.
- the phase shifter 13 is arranged so that the reflecting surfaces of the movable mirror part 131 and the fixed mirror part 132 are inclined by 45 ° with respect to the optical axis of the parallel light flux from the objective lens 7.
- the drive stage 135 moves the movable mirror 131 while maintaining the inclination of the reflecting surface of the movable mirror 131 with respect to the optical axis at 45 °.
- the amount of movement of the movable mirror 131 in the optical axis direction is ⁇ 2 of the amount of movement of the drive stage 135.
- the optical path length difference that gives a relative phase change between the two light beams of the fixed light beam and the movable light beam is twice the amount of movement of the movable mirror 131 in the optical axis direction.
- the movable mirror part 131 and the fixed mirror part 132 are arranged obliquely in this way, a beam splitter for branching the light beam becomes unnecessary, and the utilization efficiency of the object light can be increased.
- the analyzer 15 is installed in a so-called open Nicol state that transmits a linearly polarized light component in the same direction as the polarizer 5. Therefore, when the sample S does not have birefringence, the linearly polarized light component transmitted from the light source 3 through the polarizer 5 through the measurement object reaches the imaging lens 17 as it is unless the phase shift operation is performed.
- the light receiving surface of the detector 19 is located at a position that becomes the image forming surface of the imaging lens 17, and the linearly polarized component that has reached the imaging lens 17 is condensed on the same point on the light receiving surface of the detector 19.
- the analyzer 15 may be installed such that the polarization extraction angle with respect to the polarizer 5 is 45 °.
- the direction of the polarization extraction angle of the analyzer 15 may be either.
- the analyzer 15 is installed in this way, when the sample S does not have birefringence, the linearly polarized light component that has passed through the measurement object through the polarizer 5 does not pass through the analyzer 15 but the birefringence of the sample S.
- the linearly polarized light component rotated by 45 ° by the nature passes through the analyzer 15.
- the detector 19 is composed of, for example, a two-dimensional CCD camera, and the detection signal is input to the processing unit 23 and processed.
- the processing unit 23, the lens driving mechanism 21, the driving stage 135, and the like are controlled by the control unit 25.
- the x axis indicates the polarization direction of the first polarizing plate 9 and the y axis indicates the polarization direction of the second polarizing plate 11.
- the z-axis is orthogonal to the x-axis and y-axis and indicates the traveling direction of light. 4 (a) and 4 (b), the vibration in the oblique direction indicated by the solid line L is the observed linearly polarized light, that is, the vibration of the electric field vector of the linearly polarized component irradiated to the sample S through the polarizer 5. .
- the electric field component When viewed from the traveling direction, the electric field component linearly vibrates in an oblique 45 ° direction, which is called linearly polarized light. This is considered by vector decomposition into orthogonal components in the x and y directions. That is, it is considered that the electric field component indicated by the two-dot chain line Lx and the electric field component indicated by the one-dot chain line Ly vibrate synchronously, and the linearly polarized light of the solid line L is observed as a combined vector thereof.
- the phase difference between the electric field oscillations in the x and y directions is ⁇ / 4 due to the birefringence of the substance.
- the resultant vector is determined only by the x-direction component (two-dot chain line Lx).
- the x-direction component two-dot chain line Lx
- the combined vector is determined only by the y-direction component (one-dot chain line Ly).
- the phase shifter 13 can give an arbitrary phase difference between the first polarized light transmitted through the first polarizing plate 9 and the second polarized light transmitted through the second polarizing plate 11. Therefore, when the movable mirror unit 131 is gradually moved to change the optical path length difference between the first polarized light and the second polarized light continuously and temporally, and the phase difference between the two is changed, the light source 3 If the light from the monochromatic light is monochromatic light, the imaging intensity transmitted through the analyzer 15 arranged in open Nicol with respect to the polarizer 5 is the highest when a phase difference amount for canceling retardation is given as shown in FIG. Become stronger.
- phase difference amount ⁇ / 2 is further given to the phase difference amount, it becomes linearly polarized light in a direction orthogonal to the direction of linearly polarized light irradiated from the polarizer 5 to the sample S, so that it cannot pass through the analyzer 15 and forms an image.
- the intensity is the smallest.
- the phase difference amount ⁇ / 2 is given and the phase difference becomes one wavelength ( ⁇ )
- the linearly polarized light in the same direction as the linearly polarized light irradiated from the polarizer 5 to the sample S is obtained again, so that the imaging intensity is the strongest.
- a sinusoidal change in imaging intensity is repeated every time the amount of phase difference between the first polarization and the second polarization reaches one wavelength.
- FIG. 10A a composite waveform similar to the interferogram of Fourier spectroscopy can be observed.
- a general Fourier spectroscopic interferogram does not reflect birefringence, and therefore has a waveform in which light of all wavelengths is intensified at a position where the amount of phase difference is zero.
- the processing unit 23 mathematically performs Fourier transform to simultaneously analyze the amplitude and phase difference amount for each wavelength. Can be obtained.
- the spectral characteristic that is the relative intensity for each wavelength can be obtained in the same manner as Fourier spectroscopy.
- the retardation for every wavelength can be acquired from the phase difference term calculated by Fourier transform. That is, spectral characteristics and birefringence can be measured simultaneously.
- the optical system is an imaging optical system
- two-dimensional measurement of spectral characteristics and birefringence becomes possible.
- the retardation of the object light reflected from an arbitrary depth can be obtained. Since the retardation is a value obtained by adding the length of the path of the object light to the birefringence, the birefringence can be calculated from the retardation if the depth at which the object light is reflected is known.
- FIG. 11 to FIG. 14 show the results of measuring the spectral characteristics of a stone made of granite by replacing the optical system of the optical characteristic measuring apparatus 1 shown in FIG. 1 with an oblique illumination optical system.
- the amount of light captured using the oblique illumination optical system is significantly reduced, but as shown in FIG. 11, partially bright spots (indicated by symbols P1 to P3) were confirmed.
- P1 to P3 were confirmed.
- the surface of the stone used for observation is polished in a mirror shape, these bright portions P1 to P3 are considered to be portions where diffuse reflection components from the inside of the stone are observed.
- FIG. 12 shows a spectrum in which the horizontal axis is wavelength (nm) and the vertical axis is intensity
- FIG. 13 is a graph in which the horizontal axis is wavelength (nm) and the vertical axis is phase difference (deg.). It is a plot.
- the amount of retardation changed greatly except for the peak wavelength of the light source spectrum, and was relatively stable near the peak wavelength (540 to 560 nm). The reason why the retardation amount greatly changes except for the peak wavelength is considered to be because phase measurement when the emission intensity is very low is not stable.
- a characteristic reflection intensity was observed around a wavelength of 700 nm.
- FIG. 14 shows the intensity distribution and phase distribution in the wavelength ranges 540 to 560 nm, 570 to 590 nm, and 670 to 720 nm, which are characteristic of the spectrum. From FIG. 14, a characteristic phase distribution was measured in the wavelength range of 540 to 560 nm, and a characteristic intensity distribution was measured in the wavelength range of 670 to 720 nm. Accordingly, it was confirmed that the spectral characteristic measuring apparatus 1 using the oblique illumination method can simultaneously measure both the spectral characteristic and the birefringence characteristic of the internal reflection component of the stone.
- optical characteristic measuring apparatus 1 shows an optical characteristic measuring apparatus 1 according to the second embodiment.
- the optical characteristic measuring apparatus 1 according to the second embodiment is greatly different from the first embodiment in the configuration of the phase shifter and the imaging optical system.
- FIG. 12 for the sake of convenience, the illustration of the analyzer 15 disposed in front of the imaging lens 35 constituting the imaging optical system is omitted.
- Example 2 the linearly polarized light component emitted from the light source 3 and transmitted through the polarizer 5 is applied to the linear measurement region S1 of the sample S.
- a light beam irradiated on the measurement region S1 of the sample S and transmitted through the measurement region S1 enters the objective lens 7 and is converted into a parallel light beam, and then passes through the first polarizing plate 9 and the second polarizing plate 11, and then the phase shifter 31. To reach.
- the phase shifter 31 includes a reference mirror unit 32, an inclined mirror unit 33, a holding unit (not shown) that holds the mirror units 32 and 33, and the like.
- the surfaces (reflecting surfaces) of the reference mirror unit 32 and the inclined mirror unit 33 are optically flat and are rectangular optical mirror surfaces that can reflect the wavelength band of light to be measured by the apparatus 1. Further, the reflecting surfaces of the reference mirror part 32 and the inclined mirror part 33 have substantially the same size.
- the objective lens 7, the first polarizing plate 9, and the second polarizing plate 11 correspond to a split optical system
- the phase shifter 31 corresponds to a phase change applying unit.
- the light beam that reaches the analyzer 15 from the first polarizing plate 9 and reaches the reflecting surface of the reference mirror portion 32 of the phase shifter 31 is reflected as a reference light beam, and the light beam from the second polarizing plate 11 to the phase shifter 31.
- a light beam that reaches the reflection surface of the inclined mirror portion 33 and is reflected and reaches the analyzer 15 is also referred to as an inclined light beam.
- the reference mirror section 32 is arranged such that the reflection surface is inclined by 45 °, for example, with respect to the optical axis of the parallel light flux from the objective lens 7. Further, the tilting mirror portion 33 is disposed so that the reflection surface is tilted by (45 + ⁇ ) ° with respect to the optical axis of the parallel light flux from the objective lens 7.
- the objective lens 7 is used, but this function can also be configured by a reflection optical system. In this way, the influence of dispersion is completely eliminated, so that broadband spectral characteristics can be measured.
- the tilt angle of the tilt mirror 33 with respect to the reference mirror 32 that is, ⁇ is set based on optical conditions such as the magnification of the imaging optical system, the measurement wavelength range, and the wave number resolution.
- the measurement wavelength is changed from the visible region to the near infrared region (400 nm to 1000 nm)
- the phase shift amount ⁇ 100 ⁇ m.
- the number of pixels in one line is about 500 pixels.
- the phase difference amount for each pixel is 200 nm, and measurement is possible from the sampling theorem to the wavelength of 400 nm.
- the measurement wavelength is from the visible region to the near infrared region (400 nm to 1000 nm)
- the sampling theorem on the short wavelength side is satisfied when the phase difference amount for each pixel is 200 nm.
- the phase shift amount per line of a general CCD camera is 100 ⁇ m, 50 ⁇ m (100 ⁇ m ⁇ 2), which is half of that, may be set as the maximum width of the reference mirror section 32 and the tilt mirror section 33.
- the inclination angle is about 1 deg.
- the long wavelength region such as mid-infrared light
- the envelope of the interference intensity change must be acquired in the long stroke phase shift region. This is also known from the fact that, as the principle of Fourier spectroscopy, in order to increase the wave number resolution, the phase shift amount must be increased.
- the amount of phase shift needs to be about 50 mm, for example. Therefore, the length along the optical path direction may be increased to, for example, 100 mm to have a slope of 2.9 deg.
- the imaging lens 35 is formed of a cylindrical lens, and is arranged so that the convex surface portion faces the phase shifter 31 side and the flat surface portion faces the light receiving surface 19 a side of the detector 19. Since the light receiving surface 19a of the detector 19 is located on the image forming surface of the image forming lens 35, it is emitted from one bright spot of the measurement region S1, reflected by the reflecting surfaces of the reference mirror unit 32 and the inclined mirror unit 33, and then connected.
- the reference light beam and the tilted light beam incident on the image lens 35 are converged only in one direction by the imaging lens 35, and are focused on the same straight line on the light receiving surface 19a of the detector 19 to form an image.
- the imaging lens 35 is arranged so that the direction of curvature of the convex portion (the direction indicated by the arrow B in FIG. 12) is parallel to the direction of the measurement region S1. .
- the reference light beam and the inclined light beam incident on the imaging lens 35 are collected on a straight line on the light receiving surface 19a and orthogonal to the measurement region S1.
- the reflecting surface of the reference mirror unit 32 and the reflecting surface of the inclined mirror unit 33 are accurate to such an extent that the light collecting positions of the two light beams do not deviate on the light receiving surface 19a (imaging surface) of the detector 19 (two-dimensional CCD camera). It is configured to be relatively parallel surfaces.
- the measurement principle of this example will be described.
- a description will be given based on an optical model in which the reference light beam is focused on a straight line as a wave whose phases are aligned on the light receiving surface 19 a of the detector 19 by the imaging lens 35.
- the inclined light beam is focused on the light receiving surface 19a in a straight line as a wave whose phase is gradually shifted from the phase of the reference light beam.
- the light beam that has passed through the measurement region S 1 of the sample S passes through the objective lens 7, the first polarizing plate 9, and the second polarizing plate 11, and reaches the surfaces of the reference mirror unit 32 and the tilting mirror unit 33 of the phase shifter 31. To reach. At this time, the light beam reaches the surface of the reference mirror part 32 and the surface of the inclined mirror part 33 by being divided into two parts in the vertical direction.
- the surface area of both mirror portions 32 and 33 is such that the light flux reaching the surface of the reference mirror portion 32, that is, the reference light flux, and the light flux reaching the surface of the tilt mirror portion 33, that is, the amount of light of the tilted light flux are substantially equal.
- it is also possible to equalize the light quantity by adjusting the relative light quantity difference by installing a neutral density filter in one or both optical paths of the reference light beam and the tilted light beam.
- the light beams reflected by the surfaces of the reference mirror unit 32 and the inclined mirror unit 33 enter the imaging lens 35 as the reference light beam and the inclined light beam, respectively, and are collected on the same straight line on the light receiving surface 19a of the detector 19 and interfere. Form an image.
- the reference light beam is configured to be condensed as a wave having a uniform phase on the light receiving surface 19a, which is the image forming surface, through the image forming lens 35. Therefore, as shown in FIG. Is parallel to the light receiving surface 19a of the detector 19.
- the inclined light beam is incident on the imaging lens 35 with its optical axis inclined by 2 ⁇ ⁇ ° with respect to the optical axis of the reference light beam, so that the wave surface of the inclined light beam is slightly inclined with respect to the light receiving surface 19a. It becomes a state.
- the optical path length difference between the two light beams gradually changes in the interference region between the light of the reference light beam and the light of the inclined light beam (see FIG. 14 is gradually increased from the right side to the left side). That is, in the first embodiment, the movable mirror 131 is gradually moved to give a continuously changing phase difference between the first polarized light and the second polarized light.
- the reference mirror 32 is used. On the other hand, by arranging the mirror parts 32 and 33 in a state where the tilting mirror part 33 is tilted, a continuous phase difference change is given between the first polarized light and the second polarized light.
- the phase difference changes with time, but in the second embodiment, the phase difference changes spatially. Since the light emitted from the measurement region S1 includes light of various wavelengths (and the initial phases of the light of each wavelength are not necessarily aligned), the optical path length difference between the reference light beam and the inclined light beam in the interference region is continuous. As a result, it is possible to observe a composite waveform similar to the interferogram as shown in FIG. 10A from the difference in retardation for each wavelength.
- a light beam emitted from a bright spot (measurement point) a1 in the measurement region S1 is condensed on a straight line on the light receiving surface 19a (imaging plane), thereby forming a linear interference image.
- b1 is obtained, and the light beam emitted from the bright spot (measurement point) a2 is condensed on a straight line on the light receiving surface 19a, whereby a linear interference image b2 is obtained.
- the combined waveform of each interference image b1 and b2 is obtained from the received light intensity of a plurality of pixels lined up along the interference image. Therefore, in Example 2, in FIG.
- the horizontal axis indicates the pixel numbers of the detectors 19 arranged along the linear interference image
- the vertical axis indicates the imaging intensity (the received light intensity of each pixel). become.
- the processing unit 23 can acquire the spectral characteristics and the retardation for each wavelength, which are the relative intensities for each wavelength of the light emitted from each bright spot in the measurement region S1, by performing Fourier transform on the combined waveform. If spectral characteristics can be obtained using all the pixels of the detector 19, one-dimensional spectroscopic measurement of the measurement region S1 is possible. Further, if the measurement region S1 irradiated with linearly polarized light is scanned, two-dimensional spectroscopic measurement of the measurement object S can be performed. Further, the measurement region S1 is scanned, and the objective lens 7 is moved to scan the in-focus surface (surface including the in-focus position), thereby enabling three-dimensional spectroscopic measurement.
- the imaging lens 35 is composed of a reference lens unit 35 a and a tilted mirror unit 33 on which the reference light beam reflected by the reference mirror unit 32 is incident. It is divided into an inclined lens portion 35b on which the reflected inclined light beam is incident.
- the reference lens part 35a and the inclined lens part 35b have a shape obtained by dividing the imaging lens 35 of the second embodiment into two parts, and maintain the inclination of the other optical axis with respect to one optical axis of the reference light beam and the inclined light beam.
- the other optical axis is displaced along the linear interference image formed on the light receiving surface 19a (imaging surface) of the detector 19 as it is. That is, the reference lens part 35a and the inclined lens part 35b function as an imaging optical system and an optical axis position changing unit. With such a configuration, as shown in FIG. 21, it is possible to increase an area where the light of the reference light beam and the light of the inclined light beam overlap on the light receiving surface 19a, that is, the interference region.
- FIG. 22 shows Embodiment 4 of the present invention.
- a monochromatic light converting means 41 such as a fluorescent plate for converting the light intensity into monochromatic light is installed at the position of the imaging plane in the second embodiment, and the cylindrical lens 43 is disposed at a position where this is used as the object plane. It is arranged.
- the detector 19 is arranged so that the light receiving surface 19 a of the detector 19 is positioned on the optical Fourier transform surface of the cylindrical lens 43.
- the cylindrical lens 43 is arranged so that the direction having no curvature is orthogonal to the direction in which the linear interference image extends.
- the interference image of the reference light beam and the inclined light beam transmitted through the imaging lens 35 is converted into a spatial brightness intensity distribution by the monochromatic light converting means 41. And it optically Fourier-transforms with the cylindrical lens 43, and a spectrum is formed in real time on an image formation surface. Since the light receiving surface 19a of the detector 19 is on the Fourier transform surface of the cylindrical lens 43, the resultant waveform obtained in the second embodiment is mathematically Fourier transformed by optically obtaining the light intensity distribution of the spectral spectrum. The same spectral characteristics and birefringence as those obtained are obtained.
- the monochromatic light converting means 41 and the cylindrical lens 43 constitute a spectroscopic optical system.
- the analyzer 15 disposed in front of the imaging lens 17 in the first embodiment may be disposed after the imaging lens 17.
- the analyzer 15 it is preferable that the analyzer 15 be disposed in front of the imaging lens as in the first embodiment.
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Abstract
Description
a)直線偏光が入射された被測定物から発せられる光を第1偏光板及び第2偏光板に導く分割光学系と、
b)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分の合成成分のうち、所定の偏光方向の光を透過させる検光子と、
c)前記検光子を透過した光を同一点に導き干渉像を形成する結像光学系と、
d)前記干渉像の光強度を検出する検出部と、
e)前記第1偏光板及び第2偏光板から前記検光子に向かう第1偏光成分及び第2偏光成分の光路長の差を変化させることにより当該第1偏光成分と第2偏光成分の間の位相差を変化させる位相差付与手段と、
f)前記位相差の変化に伴い前記検出部で検出される光強度の変化のデータをフーリエ変換することにより前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得する処理部と
を備えることを特徴とする。
a)直線偏光が入射された被測定物から発せられる光を第1偏光板及び第2偏光板に導く分割光学系と、
b)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分の合成成分のうち所定の偏光方向の光を透過させる検光子と、
c)前記検光子を透過した光を、前記第1偏光成分及び第2偏光成分の光軸と異なる向きに延びる同一直線上に集光させて線状の干渉像を形成する結像光学系と、
d)前記第1偏光板及び第2偏光板から前記検光子に向かう第1偏光成分及び第2偏光成分の間に連続的な光路長差分布を与えることにより当該第1偏光成分と第2偏光成分の間に連続的な位相変化を与える位相変化付与手段と、
e)前記線状の干渉像の該干渉像の延びる方向に沿った光強度分布を検出する検出部と、
f)前記検出部で検出される前記干渉像の光強度分布を示すデータをフーリエ変換することにより前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得する処理部と
を備えることを特徴とする。
a)直線偏光が入射された被測定物から発せられる光を第1偏光板及び第2偏光板に導く分割光学系と、
b)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分の合成成分のうち、所定の偏光方向の光を透過させる検光子と、
c)前記検光子を透過した光を、前記第1偏光成分及び第2偏光成分の光軸と異なる向きに延びる同一直線上に集光させて線状の干渉像を形成する結像光学系と、
d)前記第1偏光板及び第2偏光板から前記検光子に向かう第1偏光成分及び第2偏光成分の間に連続的な光路長差分布を与えることにより当該第1偏光成分と第2偏光成分の間に連続的な位相変化を与える位相変化付与手段と、
e)前記線状の干渉像を波長分解して分光スペクトルを形成する分光光学系と、
f)前記分光スペクトルの光強度分布を検出する検出部と、
g)前記検出部で検出される光強度分布から前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得する処理部と
を備えることを特徴とする。
前記分割光学系が、前記被測定物から発せられた光を平行光線化して第1偏光板及び第2偏光板に導く対物レンズを備え、
前記処理部は、前記被測定物のうち前記対物レンズの合焦点から発せられる光の波長毎の振幅と複屈折位相差(位相差量)を求めるようにすると良い。
a)直線偏光を被測定物に入射させ、
b)前記直線偏光が入射された被測定物から発せられる光を分割光学系によって第1偏光板及び第2偏光板にそれぞれ導き、
c)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分を、該第1偏光成分と該第2偏光成分の光路長の差を変化させつつ検光子を介して結像光学系に導くと共に、該結像光学系によって同一点に集光させて干渉像を形成させ、
d)前記干渉像の光強度の変化を示すデータをフーリエ変換することにより前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得することを特徴とする。
a)直線偏光を被測定物に入射させ、
b)前記直線偏光が入射された被測定物から発せられる光を分割光学系によって第1偏光板と第2偏光板にそれぞれ導き、
c)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分を、該第1偏光成分と第2偏光成分の間に連続的な光路長差分布を付与しつつ検光子を介して結像光学系に導くと共に、該結像光学系によって同一直線上に集光させて線状の干渉像を形成させ、
d)前記線状の干渉像の該干渉像が延びる方向に沿った光強度分布を示すデータをフーリエ変換することにより前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得することを特徴とする。
a)直線偏光を被測定物に入射させ、
b)前記直線偏光が入射された被測定物から発せられる光を分割光学系によって第1偏光板と第2偏光板にそれぞれ導き、
c)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分を、該第1偏光成分と第2偏光成分の間に連続的な光路長差分布を付与しつつ検光子を介して結像光学系に導くと共に、該結像光学系によって同一直線上に集光させて線状の干渉像を形成させ、
d)前記線状の干渉像を分光光学系によって波長分解することにより分光スペクトルを取得し、
e)前記分光スペクトルの光強度分布に基づき前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得することを特徴とする。
なお、2つの光が同一の「点」に導かれて干渉する場合は、厳密には「干渉像」ではなく「干渉光」であるが、ここでは、2つの光が干渉することにより形成されるものを全て「干渉像」と呼ぶこととする。
これに対して本発明では、被測定物から発せられた光を分割光学系によって第1偏光成分と第2偏光成分に分割し、これら偏光成分を別々の光路で結像光学系に向かわせた後、該結像光学系によって同一点に導いて干渉させる。合焦面から発せられた光のみが、結像光学系の結像面上で干渉するため、本発明では、結像光学系の結像面上に検出部の受光面を位置させることにより、被測定物のうち合焦面に相当する部分、つまり、被測定物内の特定の深度から発せられた光の干渉光のみを検出部で検出することができ、雑音の少ない明瞭な干渉像を得ることができる。
なお、図1及び図2には、試料Sを透過した光を測定する透過型の光学特性測定装置1を示したが、試料Sの内部から反射してきた光を測定する反射型の光学特性測定装置でもよい。試料を透過してきた光、及び、試料の内部で反射してきた光は、いずれも試料中の成分の複屈折性と吸光特性を有するからである。
図3に示すように、第1偏光板9及び第2偏光板11は、その偏光方向が偏光子5を透過してきた直線偏光成分の電界ベクトルの振動方向に対して45°傾くように、且つ、第1偏光板9の偏光方向と第2偏光板11の偏光方向が互いに直交するように設置される。以下の説明では、第1偏光板9の偏光方向をx方向、第2偏光板11の偏光方向をy方向ともいう。また、第1偏光板9を透過した光を第1偏光、第2偏光板11を透過した光を第2偏光という。
検出器19は例えば二次元CCDカメラから構成されており、その検出信号は処理部23に入力されて処理される。また、処理部23、レンズ駆動機構21、駆動ステージ135等は制御部25によって制御される。
一方、図13に示すように、レターデーション量は、光源スペクトルのピーク波長以外では大きく変化し、ピーク波長(540~560nm)付近では、比較的安定していた。ピーク波長以外でリタデーション量が大きく変化している理由は、発光強度が非常に低いときの位相計測が安定しないためと考えられる。なお、P2及びP3の箇所では、波長700nm近辺に特徴的な反射強度が観察された。
実施例2では、光源3から出射され、偏光子5を透過した直線偏光成分は、試料Sの線状の測定領域S1に照射される。試料Sの測定領域S1に照射され、該測定領域S1を透過した光線は対物レンズ7に入射し、平行光束に変換された後、第1偏光板9及び第2偏光板11を経て位相シフター31に到達する。
なお、以下の説明では、第1偏光板9から位相シフター31の基準ミラー部32の反射面に到達して反射され、検光子15に至る光束を基準光束、第2偏光板11から位相シフター31の傾斜ミラー部33の反射面に到達して反射され、検光子15に至る光束を傾斜光束ともいう。
また、特に、中赤外光などの長波長領域においては、インターフェログラムの干渉強度変化だけでなく、干渉強度変化の包絡線を長ストロークの位相シフト領域において取得しなくてはならない。これは、フーリエ分光の原理として、波数分解能を高くするためには位相シフト量を長くしなくてはならないことからも知られている。このように、長ストロークに渡ってインターフェログラムの包絡線を検出するためには、傾斜ミラー部33に大きな傾斜角を設けなくてはならない。この場合、インターフェログラムの干渉強度変化を検出するためと、包絡線を検出するための2段階程度の傾き切り替え機構を設ければよい。中赤外領域で包絡線を計測する場合、位相シフト量が例えば50mm程度が必要になることから、光路方向に沿う長さを例えば100mmに長くして2.9deg.の傾きにすればよい。
基準ミラー部32の反射面と傾斜ミラー部33の反射面は、検出器19(二次元CCDカメラ)の受光面19a(結像面)で2つの光束の集光位置がずれない程度の精度で、相対的に平行な面となるように構成されている。
測定領域S1から発せられる光束には様々な波長の光が含まれる(且つ各波長の光の初期位相が必ずしも揃っていない)ことから、干渉領域の基準光束と傾斜光束の間の光路長差が連続的に変化することにより、また、波長毎のリタデーションの違いから、図10(a)に示すようなインターフェログラムと似た合成波形を観察することができる。
このような構成により、図21に示すように、受光面19a上において基準光束の光と傾斜光束の光が重複する領域、つまり干渉領域を大きくすることができる。
3…光源
5…偏光子
7…対物レンズ
9…第1偏光板
11…第2偏光板
13、31…位相シフター
15…検光子
17…結像レンズ
19…検出器
19a…受光面
21…レンズ駆動機構
23…処理部
25…制御部
32…基準ミラー部
33…傾斜ミラー部
35…結像レンズ
35a…基準レンズ部
35b…傾斜レンズ部
41…単色光変換手段
43…シリンドリカルレンズ
131…可動ミラー部
132…固定ミラー部
Claims (9)
- a)直線偏光が入射された被測定物から発せられる光を第1偏光板及び第2偏光板に導く分割光学系と、
b)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分の合成成分のうち、所定の偏光方向の光を透過させる検光子と、
c)前記検光子を透過した光を同一点に導き干渉像を形成する結像光学系と、
d)前記干渉像の光強度を検出する検出部と、
e)前記第1偏光板及び第2偏光板から前記検光子に向かう第1偏光成分及び第2偏光成分の光路長の差を変化させることにより当該第1偏光成分と第2偏光成分の間の位相差を変化させる位相差付与手段と、
f)前記位相差の変化に伴い前記検出部で検出される光強度の変化のデータをフーリエ変換することにより前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得する処理部と
を備えることを特徴とする光学特性測定装置。 - a)直線偏光が入射された被測定物から発せられる光を第1偏光板及び第2偏光板に導く分割光学系と、
b)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分の合成成分のうち所定の偏光方向の光を透過させる検光子と、
c)前記検光子を透過した光を、前記第1偏光成分及び第2偏光成分の光軸と異なる向きに延びる同一直線上に集光させて線状の干渉像を形成する結像光学系と、
d)前記第1偏光板及び第2偏光板から前記検光子に向かう第1偏光成分及び第2偏光成分の間に連続的な光路長差分布を与えることにより当該第1偏光成分と第2偏光成分の間に連続的な位相変化を与える位相変化付与手段と、
e)前記線状の干渉像の該干渉像の延びる方向に沿った光強度分布を検出する検出部と、
f)前記検出部で検出される前記干渉像の光強度分布を示すデータをフーリエ変換することにより前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得する処理部と
を備えることを特徴とする光学特性測定装置。 - a)直線偏光が入射された被測定物から発せられる光を第1偏光板及び第2偏光板に導く分割光学系と、
b)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分の合成成分のうち、所定の偏光方向の光を透過させる検光子と、
c)前記検光子を透過した光を、前記第1偏光成分及び第2偏光成分の光軸と異なる向きに延びる同一直線上に集光させて線状の干渉像を形成する結像光学系と、
d)前記第1偏光板及び第2偏光板から前記検光子に向かう第1偏光成分及び第2偏光成分の間に連続的な光路長差分布を与えることにより当該第1偏光成分と第2偏光成分の間に連続的な位相変化を与える位相変化付与手段と、
e)前記線状の干渉像を波長分解して分光スペクトルを形成する分光光学系と、
f)前記分光スペクトルの光強度分布を検出する検出部と、
g)前記検出部で検出される光強度分布から前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得する処理部と
を備えることを特徴とする光学特性測定装置。 - 第1偏光成分と第2偏光成分の偏光方向が直交し、且つ前記被測定物に入射する直線偏光の電界成分に対して第1偏光成分と第2偏光成分の偏光方向が45°傾くように、第1偏光板及び第2偏光板が配置されていることを特徴とする請求項1~3のいずれかに記載の光学特性測定装置。
- 前記分割光学系が、前記被測定物から発せられた光を平行光線化して第1偏光板及び第2偏光板に導く対物レンズを備え、
前記処理部は、前記被測定物のうち前記対物レンズの合焦点から発せられた光の波長毎の振幅と複屈折位相差を求めることを特徴とする請求項1~4のいずれかに記載の光学特性測定装置。 - 前記被測定物に対する前記対物レンズの合焦位置を相対的に変更する合焦位置変更手段を備えることを特徴とする請求項5に記載の光学特性測定装置。
- a)直線偏光を被測定物に入射させ、
b)前記直線偏光が入射された被測定物から発せられる光を分割光学系によって第1偏光板及び第2偏光板にそれぞれ導き、
c)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分を、該第1偏光成分と該第2偏光成分の光路長の差を変化させつつ検光子を介して結像光学系に導くと共に、該結像光学系によって同一点に集光させて干渉像を形成させ、
d)前記干渉像の光強度の変化を示すデータをフーリエ変換することにより前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得することを特徴とする光学特性測定方法。 - a)直線偏光を被測定物に入射させ、
b)前記直線偏光が入射された被測定物から発せられる光を分割光学系によって第1偏光板と第2偏光板にそれぞれ導き、
c)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分を、該第1偏光成分と第2偏光成分の間に連続的な光路長差分布を付与しつつ検光子を介して結像光学系に導くと共に、該結像光学系によって同一直線上に集光させて線状の干渉像を形成させ、
d)前記線状の干渉像の該干渉像が延びる方向に沿った光強度分布を示すデータをフーリエ変換することにより前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得することを特徴とする光学特性測定方法。 - a)直線偏光を被測定物に入射させ、
b)前記直線偏光が入射された被測定物から発せられる光を分割光学系によって第1偏光板と第2偏光板にそれぞれ導き、
c)前記第1偏光板を透過した第1偏光成分と前記第2偏光板を透過した第2偏光成分を、該第1偏光成分と第2偏光成分の間に連続的な光路長差分布を付与しつつ検光子を介して結像光学系に導くと共に、該結像光学系によって同一直線上に集光させて線状の干渉像を形成させ、
d)前記線状の干渉像を分光光学系によって波長分解することにより分光スペクトルを取得し、
e)前記分光スペクトルの光強度分布に基づき前記被測定物から発せられる光の波長毎の振幅と複屈折位相差を取得することを特徴とする光学特性測定方法。
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