JP3513566B2 - Optical interface dimension measuring device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical interfacial dimension measuring apparatus for optically measuring the optical dimension between the interfaces of a subject having a plurality of interfaces, and particularly to, for example, a lens system having a large number of lenses. The present invention relates to a measuring device for measuring the thickness of each lens, the distance between lenses, and the optical dimension between interfaces of a complicated optical system such as a corner cube.

[0002]

2. Description of the Related Art Generally, a highly accurate lens system having a small aberration is constructed by combining a large number of lenses. It is necessary to set.

Conventionally, in the inspection process when manufacturing such a lens system, the thickness of each lens is mechanically measured by using a micrometer, a caliper, or the like, and the lens interval is mechanically measured by using a dial gauge or the like. However, the work is extremely laborious and time-consuming, and is not always sufficient in terms of measurement accuracy. In addition, it is necessary to remove each lens incorporated in the lens barrel and then perform measurement, which is not efficient in terms of manufacturing technology.

In the optical length measurement using an interferometer or the like, a corner cube is usually used as a reflecting mirror, and the optical dimension between predetermined positions of this corner cube is measured to accurately estimate the optical center. This is the key to highly accurate optical measurement of length. However, such a corner cube is usually chamfered, and it is necessary to set a virtual edge for this chamfered portion and then measure the dimension and angle of the surface, which makes direct measurement using mechanical means difficult. Met.

Further, as a method of measuring the thickness of the optical member in a non-contact manner, each position of the lens barrel in which each surface of the optical member is in focus is measured using a microscope, and refraction is performed at intervals between these measuring positions. It is known that the value obtained by multiplying the ratio is obtained as the thickness of the optical member. However, such a method using a microscope has a limit in working distance,
It is difficult to measure only a thin optical member, and there is a problem in terms of measurement accuracy.

In addition to such a method of measuring the interfacial distance mechanically or using a microscope, an optical length measuring method using continuous wave laser light (CW light) as probe light is also known. If such an optical length measuring method is used, it is possible to measure the length in a non-contact manner, and although the troublesomeness of the above-described conventional technique is improved, a lens system or a corner cube having a large number of lenses can be used. In such a complicated optical system, the reflected lights from the multiple surfaces are superimposed on each other, which makes it difficult to accurately measure the interfacial dimension.

The present invention has been made in view of the above circumstances, and provides an optical interfacial dimension measuring apparatus which is simple in measurement operation and capable of highly accurate interfacial dimension measurement regardless of the thickness of a subject. It is intended to be provided.

[0008]

A first optical interfacial dimension measuring device of the present invention separates a pulsed light output means and pulsed light from this pulsed light output means into two systems, one of which is provided with a plurality of devices. As a probe light to the subject having an interface, a beam splitter that outputs the other as a reference light, an optical delay amount varying means that reflects the reference light and is movable so as to change the optical path length of the reference light, Reflected light from each interface of the probe light of the probe light and reflected light from the optical delay amount varying means of the reference light are incident, and when the incident timings of the pulses of these both reflected lights match, a matching pulse is generated. Generated coincidence pulse generation means, and the movement position of the optical delay amount varying means corresponding to each coincidence pulse when the coincidence pulse corresponding to each of the interfaces is output from the coincidence pulse generation means. Based on said interval is characterized in that it comprises an optical dimension calculating means for calculating an optical dimension between the interfaces of the object.

A second optical interface dimension measuring device of the present invention is the same as the first optical interface dimension measuring device, wherein an interface of the subject is provided between the beam splitter and the subject. According to the shape of the above, a condensing direction adjusting lens system which is movable in the optical axis direction and which can be adjusted so that the probe light is vertically incident on the interface is disposed.

Further, a third optical interface dimension measuring apparatus of the present invention is the same as the first optical interface dimension measuring apparatus, wherein the probe light is applied between the beam splitter and the object. It is characterized in that a focusing lens capable of focusing is disposed on the interface of the subject.

Further, a fourth optical inter-interface dimension measuring apparatus of the present invention is the apparatus according to any one of the first to third optical inter-interface dimension measuring apparatuses, wherein the beam splitter is a polarization beam splitter. Yes, a λ / 4 optical phase plate is disposed in both round-trip optical paths of the light reflected by the polarization beam splitter among the probe light and the reference light, and the reflected light of the probe light from the subject and the reference light It is characterized in that a reflecting means for reflecting either one of the reflected light from the light delay amount varying means of the light in the same direction as the traveling direction of the other is provided.

A fifth optical interfacial dimension measuring apparatus of the present invention is any one of the first to third optical interfacial dimension measuring apparatuses, wherein the beam splitter is a polarization beam splitter. Yes, a λ / 4 optical phase plate is provided in both optical paths of both the probe light and the reference light, and the reflected light from the subject of the probe light and the optical delay amount varying means of the reference light Both of the reflected lights are configured to return to the polarization beam splitter.

The sixth optical interfacial dimension measuring apparatus of the present invention reflects the pulsed light output means and most of the pulsed light from the pulsed light output means as probe light to the subject, A beam splitter, at least a part of which is provided with a highly reflective film that transmits the rest of the pulsed light as reference light, and the beam splitter is arranged in both round-trip optical paths of the probe light between the beam splitter and the subject. A λ / 4 optical phase plate and an optical path of the probe light between the beam splitter and the λ / 4 optical phase plate, the probe light from the beam splitter being transmitted, and the probe light from the subject. And a polarizing beam splitter capable of avoiding incidence of reflected light from the subject on the portion provided with the high reflection film, and reflecting the reference light, Optical delay amount varying means movable so as to change the optical path length, reflected light from each interface of the subject of the probe light and reflected light from the optical delay amount varying means of the reference light is incident, Matching pulse generating means for generating a matching pulse when the incident timings of the pulses of these two reflected lights match, and the matching pulse generating means outputs the matching pulse corresponding to each of the interfaces. It is characterized by comprising an optical dimension calculating means for calculating an optical dimension between respective interfaces of the subject based on the interval of the moving positions of the optical delay amount varying means corresponding to each coincident pulse.

The above-mentioned "optical size" is the physical distance between the interfaces multiplied by the refractive index of the substance interposed between the interfaces.

[0015]

According to the first optical interfacial dimension measuring apparatus described above, the measurement light is separated into the two systems of the probe light and the reference light by the beam splitter, and the probe light is reflected from each interface of the subject. The light and the reflected light from the optical delay amount varying means of the reference light are observed at the same time, and based on the moving position of the optical delay amount varying means when the optical path lengths of these probe light and reference light are matched, Since the optical dimension is measured, the optical dimension between the interfaces can be measured without contact.

Further, since the pulsed light is used as the measurement light, both the probe light and the reference light are pulsed light, and when both the pulsed lights are incident on the coincident pulse generating means, the coincidence is achieved. A matching pulse is output from the pulse generating means. In this way, by using pulsed light as the measurement light, when a complex optical system such as a lens system having a large number of lenses or a corner cube is used as an object to be inspected, the reflected light from the spatially superposed multiple surfaces It becomes possible to separate them temporally, and it is possible to determine with high accuracy the moving position of the optical delay amount varying means in which the optical path lengths of the probe light and the reference light are equal for each interface of the subject. By obtaining the difference, it becomes possible to easily and highly accurately measure the optical dimension between the interfaces.

It should be noted that the shorter the pulse width of the pulsed light is, the higher the resolution of measurement can be made, and the higher the measurement accuracy can be made. In particular, by using an ultra-short pulse laser such as a femtosecond pulse laser, which has been attracting attention in recent years, the effect of the present invention can be further enhanced.

According to the second optical interfacial dimension measuring apparatus of the present invention, a converging direction adjusting lens system is arranged between the beam splitter and the subject, and this lens system is used. By making it movable in the optical axis direction, the probe light is made incident vertically on this interface according to the shape of the interface of the subject, and the reflected light of the probe light from this interface has the same path as this incident light. Can be set so that the reflected light of the probe light can be efficiently incident on the matching pulse generating means.

Further, according to the third optical interfacial dimension measuring apparatus of the present invention, a focusing lens is arranged between the beam splitter and the subject, and the probe light is directed to the subject. The interface can be focused, and even if the interface has small irregularities, the proportion of scattered light from this interface can be reduced, and the reflected light of this probe light can be efficiently generated as a matching pulse. The means can be made incident.

Further, according to the fourth optical interfacial dimension measuring apparatus of the present invention, the pulsed light is separated into S-polarized light and P-polarized light by the polarization beam splitter, and one is used as the probe light and the other is used as the reference light. A λ / 4 optical phase plate is arranged on the optical path of S-polarized light reflected from the polarization beam splitter so that the return light of S-polarized light is converted into P-polarized light when it is incident on the polarization beam splitter again. And, moreover,
Since the traveling direction of one of the P-polarized light and the P-polarized light reflected from the optical delay amount varying means is aligned with the other traveling direction by using the reflecting means, the loss of the quantity of incident light in the polarization beam splitter is caused. At a minimum, the probe light and the reference light can be efficiently incident on the matching pulse generating means.

Further, according to the fifth optical interfacial dimension measuring apparatus of the present invention, λ / 4 optical phase plates are provided on both optical paths of S-polarized light and P-polarized light separated by the polarization beam splitter. , The S-polarized return light reflected by the polarization beam splitter is converted into P-polarized light and can be transmitted through the polarization beam splitter, while the P-polarized return light transmitted through the polarization beam splitter is converted into S-polarized light. The polarized light is reflected by the polarization beam splitter, and thereafter both polarized lights are aligned in the same traveling direction and are incident on the coincident pulse generating means. Therefore, compared with the above-mentioned fourth optical inter-surface dimension measuring device, the probe light There is no need for a reflection unit that aligns the traveling direction of one of the returning light of the reference light and the returning light of the reference light with the traveling direction of the other.

Further, according to the sixth optical interface dimension measuring apparatus of the present invention, the reflected light from the portion of the beam splitter provided with the highly reflective film is used as the probe light and the transmitted light is used as the reference light. Since the light amount ratio of the probe light, which requires a larger light amount to secure the reflected light amount from each interface, is increased, it is possible to improve the measurement accuracy.
Further, the probe light reflected by the beam splitter is switched between the forward path and the backward path by using a λ / 4 optical phase plate and a polarization beam splitter so that the reflected light of the probe light from the subject is detected by the beam splitter. Therefore, the presence of the highly reflective film portion does not prevent the reflected light from the subject from entering the matched pulse generating means, and The probe light can be efficiently incident on the matching pulse generating means.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing an optical interface dimension measuring apparatus according to an embodiment of the present invention. This apparatus is arranged such that an Ar ⁺ laser 1 for excitation, a mode-locked titanium sapphire laser 2 that outputs an ultrashort pulsed light 2a, and an incident angle of the ultrashort pulsed light 2a are 45 °. The beam splitter 4 for separating the probe light 2b and the reference light 2c to the sample 3 and the reference light (pump light of the matching pulse generating means 8 described later; hereinafter simply referred to as pump light) 2c are used.
There is provided a corner cube-shaped optical delay amount varying means 5 which is capable of moving in the light traveling direction and which reflects by changing its direction by 180 °. Further, the optical delay amount varying means 5 for the pump light 2c
The total reflection mirror 6 that aligns the traveling direction of the reflected light from the probe light transmitted through the beam splitter 4 with the traveling direction of the reflected light from each interface of the subject 3 and the both reflected light are focused at the same position. It is a non-linear crystal that is arranged at a position where the both reflected lights are focused by the focusing lens 7 and the focusing lens 7, and outputs the coincident pulsed light 2d only when the pulses of the two reflected lights are incident at the same timing. Matching pulse generating means 8, an aperture member 9 that transmits the matching pulsed light 2d and cuts other ambient light, and a disturbance light cut filter 10, and the matched pulsed light 2d are detected, and the detected electrical signal 12a is detected accordingly. , A moving position detecting means 13 for detecting the moving amount of the optical delay amount varying means 5, and outputting a detected electric signal 12b corresponding to the moving amount, 3, the optical size between the interfaces is calculated based on the detection of the matching pulse 2d according to the reflected light from each interface and the moving amount of the optical delay amount varying means 5, and the optical size for outputting the calculation result. The calculation means 14 is provided.

The Ar ⁺ laser 1 is set so as to output 6 W of pumping light, and the titanium sapphire laser 2 to which this pumping light is input is a so-called femtosecond light by the self mode locking method. The short pulse light 2a is output. The ultrashort pulsed light 2a has, for example, a pulse width.
117 fs, repetition frequency 76 MHz, average output 500 m
W, center wavelength 780 nm is output.

The matching pulse generating means 8 is 1 mm
A non-linear crystal made of thick LBO, which has a probe light 2
When a pulse of reflected light from each interface of the subject 3 of b and a pulse of reflected light of the pump light 2c from the optical delay amount varying means 5 are simultaneously incident, a sum frequency pulse (match pulse) of both reflected lights is generated. It is supposed to do.

Further, the optical delay amount varying means 5 is formed of a corner cube-shaped total reflection mirror which is a light reflector so as to be movable in the arrow A direction on the moving position detecting means 13 comprising a pulse stage. The moving position detecting means 13 outputs a detection pulse signal 12b according to the moving position of the total reflection mirror.

The subject 3 is a zoom lens system composed of a plurality of lenses, and in the apparatus of this embodiment, the dimension between the interfaces of these lenses is detected.

The operation of the apparatus of the above embodiment will be described below.

The ultrashort pulsed light 2a output from the titanium sapphire laser 2 is split into a probe light 2b and a pump light 2c by a beam splitter 4 consisting of a half mirror.
The probe light 2b and the pump light 2c are also ultrashort pulse lights. The probe light 2b is reflected at each lens interface of the subject 3, and reflected light is formed at each interface. The probe light 2b reflected at each interface returns to the beam splitter 4, passes through this beam splitter 4, and is made incident on a predetermined position of the nonlinear crystal forming the matched pulse generating means 8 by the focusing lens 7. On the other hand, the pump light 2c is reflected by the optical delay amount varying means 5 arranged at a predetermined moving position, and enters the predetermined position of the nonlinear crystal as the pump light 2d via the total reflection mirror 6 and the focusing lens 7.

In the matching pulse generating means 8 which is the non-linear crystal, the matching pulse 2d is generated only when the pulse of the probe light 2b and the pulse of the pump light 2c are simultaneously incident.

That is, as shown in FIG. 2 (a), the probe light 2b is transmitted at the timing of time t ₁ while the pump light 2b
When c enters the matching pulse generating means 8 at the timing of time t _2, the matching pulse 2d is not output,
As shown in FIG. 2B, probe light 2b and pump light 2c
There is output matched pulse 2d only in the timing of the time t ₃ when incident on the matching pulse generating means 8 together at time t _3.

The disturbance light (probe light 2b, pump light 2c and other noise light components) other than the matching pulse 2d is removed by the aperture member 9 and the disturbance light cut filter 10, and only the matching pulse 2d is removed by the photodiode 11. To be detected. The photodiode 11 outputs a detection electric signal 12a to the optical dimension calculating means 14 based on the light receiving timing of the matching pulse 2d.

In the optical dimension calculating means 14, each of the moving position detecting means 13 having the position information of the optical delay amount changing means 5 is triggered by using the detected electric signal 12a corresponding to the probe light 2b from each interface as a trigger pulse. The detected electric signal 12b is held, the optical dimension between the lens interfaces of the subject 3 is calculated based on the held difference of the moving position information, and the calculation result is output as a measurement value.

That is, at the timing when the detected electrical signal 12a is input to the optical dimension calculation means 14, the optical path lengths of the probe light 2b and the pump light 2c are equal values, and the optical path difference between the lens interfaces is: That is, the inter-interface optical dimension is measured by the amount of change in the optical path length of the pump light 2c. Since twice the amount of movement of the optical delay amount varying means 5 corresponds to the amount of change of the reference light 2c, the calculation processing of the optical dimension calculating means 14 is performed in consideration of this as well.

According to the apparatus of the above embodiment, while the optical delay amount varying means 5 is moved in the direction of the arrow A, the probe light 2b and the pump light 2c are caused to enter the matching pulse generating means 8, whereby the matching pulse generating means is obtained. Since the coincident pulses 2d corresponding to the respective lens interfaces are sequentially generated from 8, the optical dimensions between all the interfaces of the subject 3 can be obtained by one scanning operation of the optical delay amount varying means 5 in the direction of arrow A. The dimension measurement can be performed extremely quickly. Moreover, since the optical pulse widths of the probe light 2b and the pump light 2c are extremely short, the pulse width of the matching pulse 2d is also short, and the resolution of the above optical dimensions can be improved.

Next, FIG. 3 shows a case where a light vertical incidence optical system consisting of a convex lens 21 and a concave lens 22 is inserted between the beam splitter 4 and the subject 3 in the apparatus of the above embodiment. That is, the probe light 2b from the beam splitter 4 sequentially passes through the concave lens 22 and the convex lens 21 and is incident on the lens interface (a spherical surface centered on the center of curvature 3b) 3a of the subject 3. If the convex lens 21 is moved in the direction of the arrow B and the probe light 2b is adjusted so as to enter the lens interface 3a perpendicularly, the probe light 2b
The reflected light from the lens interface 3a of the
Beam splitter 4 following the same path as the incident path of
Will be returned to. Thereby, the probe light 2b can be efficiently returned to the beam splitter 4.

The convex lens 21 is connected to the lens interface 3a.
Probe beam 2b by moving it in the direction of arrow B according to the shape of
It is possible to deal with spherical lenses of various shapes by changing the focusing direction of.

Further, when the lens interface is a concave surface, the positions of the convex lens 21 and the concave lens 22 may be exchanged so that the concave lens 22 can be moved in the arrow B direction.

Next, FIG. 4 shows a case where the focusing lens 31 is arranged between the beam splitter 4 and the interface 3c of the subject 3 in the apparatus of the above embodiment.

That is, by using the focusing lens 31 to focus the probe light 2b on one point on the interface 3c,
The reflected light of the probe light 2b from the interface 3c can also be returned to the beam splitter 4 by tracing the incident path of the probe light from this point, whereby minute unevenness is formed on the interface 3c of the subject 3. Even, probe light 2
The proportion of diffuse reflection of b at this interface 3c becomes small, and the probe light 2b can be efficiently returned to the beam splitter 4.

Next, FIG. 5 shows a case where a polarization beam splitter 4a is used in place of the beam splitter 4 consisting of a half mirror in the apparatus of the embodiment shown in FIG.

That is, the titanium sapphire laser 2 outputs an ultra-short pulsed light 2a which is an elliptically polarized light according to the purpose, and is separated by the polarization beam splitter 4a into an S-polarized probe light 2b and a P-polarized pump light 2c. To be done.

The intensity ratio of the S-polarized light and the P-polarized light forming the ultrashort pulsed light 2a is adjusted to a value such that the ratio of the S-polarized light in the two polarized lights 2b and 2c separated by the polarization beam splitter 4a increases. Has been done.

The S-polarized probe light 2b is transmitted through the λ / 4 optical phase plate 41 to be circularly polarized. After this, the subject 3
The probe light 2b, which is circularly polarized in the opposite direction at each lens interface, passes through the λ / 4 optical phase plate 41 to be converted into P-polarized light, passes through the polarization beam splitter 4a, and passes through the converging lens 7 to generate a matching pulse. It is incident on the generating means 8.

On the other hand, the P-polarized pump light 2c is reflected by the optical delay amount varying means 5 and enters the matching pulse generating means 8 via the total reflection mirror 6 and the focusing lens 7.

As described above, by using the polarization beam splitter 4a and the λ / 4 optical phase plate 41, it is possible to prevent the probe light 2b from being reflected by the polarization beam splitter 4a, and the probe light 2b can be efficiently used. It is possible to make the coincidence pulse generation means 8 incident on.

Next, FIG. 6 shows that, in the apparatus of the embodiment shown in FIG. 1, a polarization beam splitter 4b is used in place of the beam splitter 4 consisting of a half mirror, and the probe beam 2b and the pump separated by this polarization beam splitter 4b are used. A λ / 4 optical phase plate 41 is provided in both optical paths of the light 2c.
This is a case where a and 41b are provided.

That is, the probe light 2b follows the same path as the optical system shown in FIG.
Regarding the pump light 2c, the P-polarized light output from the polarization beam splitter 4b is converted into S-polarized light by passing twice through the λ / 4 optical phase plate 41b, and is returned to the polarization beam splitter 4b. It is different from the optical system shown in FIG. Since the pump light 2c is converted into S-polarized light when entering the polarization beam splitter 4b, it is totally reflected by the polarization beam splitter 4b and is aligned in the traveling direction of the probe light 2b which has passed through the polarization beam splitter 4b.

If the λ / 4 optical phase plate 41b is inserted also in the path of the pump light 2c as in the optical system shown in FIG. 6,
The total reflection mirror 6 used in the optical system shown in FIG. 5 is unnecessary.

In the optical system shown in FIG. 7, the beam splitter 4 in the optical system shown in FIG. 1 is replaced with a beam splitter 4c consisting of a half mirror partially having a high reflection film. The route of is changed on the way out and the way back.

That is, the ultrashort pulsed light 2a output from the titanium sapphire laser 2 is emitted from the beam splitter 4c.
In the portion 4d where the high reflection film of
b is split into two lights so that the light amount ratio thereof is larger than that of the pump light 2c.

Probe light 2 from the beam splitter 4c
As for b, only the P-polarized component is selectively transmitted through the polarization beam splitter 51. The P-polarized probe light 2b is converted into S-polarized light by passing through the λ / 4 optical phase plate 41c twice, so that the subject 3
The reflected light from is reflected laterally in the polarization beam splitter 51, and the path of the probe light 2b is different between the forward path and the return path.

The probe light 2b reflected by the polarization beam splitter 51 is reflected by the total reflection mirror 52, and the transparent portion (the portion without the reflection film) 4 of the beam splitter 4c 4
After passing through e, the pump light 2c reflected by the total reflection mirror 6 and its traveling direction are aligned, and enter the matching pulse generating means 8 via the focusing lens 7.

Highly reflective film 4d of the beam splitter 4c
The portion provided with is formed to have a reflectance of, for example, about 90 to 95%, and preferably has a multilayer structure.

It is more preferable to apply an antireflection film to the transparent portion 4e of the beam splitter 4c where the high reflection film is not applied.

According to the optical system shown in FIG. 7, the ultra-short pulsed light 2a is separated at the portion 4d of the beam splitter 4c where the highly reflective film is applied to increase the light quantity ratio of the probe light 2b. Since the return light of the probe light 2b from the subject 3 is transmitted through the transparent portion 4e of the beam splitter 4c, a large light quantity is required as the probe light 2b because the light quantity is divided into reflected light of a large number of interfaces. It is particularly useful in the optical interfacial dimension measuring apparatus as in this embodiment.

The return light of the probe light 2b reflected by the polarization beam splitter 51 may be routed around the portion 4d of the beam splitter 4c provided with the high reflection film. Can also be configured to pass outside the beam splitter 4c.

The probe light 2b incident on the polarization beam splitter 51 may be elliptically polarized.
In order to reduce the loss of the amount of light, it is preferable to use P-polarized light before the polarization beam splitter 51.

Further, when the probe light 2b is weak in the apparatus of the above embodiment, a chopper is inserted in the optical path of the probe light 2b to remove the scattering of the pump light 2c, and the output signal from this chopper is used. It is preferable to detect the detection electric signal 12a from the photodiode 11 by a lock-in amplifier with reference to.

The optical interfacial dimension measuring device of the present invention is not limited to the above-mentioned embodiment.
It can be changed to various modes.

For example, in the apparatus of the above-mentioned embodiment,
Although the reflected light from the beam splitter is used as the probe light and the transmitted light is used as the pump light, the reflected light and the transmitted light can be replaced with each other.

The pulsed light output means may be any one capable of stably outputting ultrashort pulsed light, for example, A
Cr: LiSAF, CPM, KL by r ⁺ laser excitation
KLM by pumping each laser such as M and Nd: YAG laser
It is also possible to use a laser or the like.

Further, the incident angle of the ultrashort pulsed light to the beam splitter is not limited to 45 °, and its value can be changed appropriately.

Further, it is advantageous in calculating the optical path length of the pump light to make the reciprocating paths of the pump light to the optical delay amount varying means parallel to each other as in the above embodiment, but the optical path length of the pump light is If they can be specified, they are not necessarily parallel to each other.

Further, the matching pulse generating means of the present invention is not limited to that of the above-mentioned embodiment, and it can generate a predetermined pulse signal when the pulses of the probe light and the pump light are incident at the same timing. I wish I had it.

Further, although the subject in the above embodiment is a lens system in which a large number of lenses are combined, it goes without saying that the object to be measured by the device of the present invention is not limited to this.
A transparent body (solid or liquid) having a plurality of interfaces can be a measurement target.

For example, in order to measure the optical center of the corner cube, the device of the present invention can be used also when measuring the optical path length in the corner cube between the light incident position and the light exit position of the corner cube. . Further, the present invention can be applied to the case of remotely measuring the coupling state or breaking point of an optical fiber, or the case of measuring the thickness of animal skin.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an optical interfacial dimension measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart showing how matching pulses are generated when the timings of pulses of probe light and pump light match.

3 is a schematic diagram showing an optical system inserted between the beam splitter and the subject of the apparatus shown in FIG.

FIG. 4 is a schematic diagram showing an optical system inserted between the beam splitter and the subject of the apparatus shown in FIG.

FIG. 5 is a schematic view showing a partially modified example of the apparatus shown in FIG.

FIG. 6 is a schematic view showing a partially modified example of the apparatus shown in FIG.

FIG. 7 is a schematic view showing a partially modified example of the apparatus shown in FIG.

[Explanation of symbols]

1 Ar ⁺ Laser 2 Titanium Sapphire Laser 2a Ultra Short Pulse Light 2b Probe Light 2c Pump Light 2d Matching Pulse 3 Specimen 4, 4c Beam Splitter 4a, 4b, 51 Polarization Beam Splitter 5 Optical Delay Amount Adjusting Unit 6,52 Total Reflection Mirror 7, 31 Focusing lens 8 Matching pulse generating means 9 Aperture member 10 Ambient light cut filter 11 Photodiodes 12a, 12b Detection electric signal 13 Moving position detecting means 14 Optical dimension calculating means 21 Convex lens 22 Concave lenses 41, 41a, 41b, 41c ... λ / 4 optical phase plate

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kaoru Minoshima Kaoru 1-4 1-4 Umezono, Tsukuba-shi, Ibaraki Institute of Industrial Science and Technology (72) Inventor Tetsuo Udagawa 1-324 Uetake-cho, Omiya-shi, Saitama Fujishi Photo Kouki Co., Ltd. (72) Inventor Fumio Kobayashi 1-324 Uetakecho, Omiya City, Saitama Fuji Photo Co., Ltd. (56) Reference JP-A-6-230128 (JP, A) JP-A-6 -307818 (JP, A) JP-A-4-66832 (JP, A) JP-B-46-31378 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 11/00- 11/30 G01S 17/10 G01M 11/00

Claims (6)

(57) [Claims] 1. A pulsed light output means and a pulsed light from this pulsed light output means are separated into two systems,
A beam splitter that outputs one as probe light to a subject having a plurality of interfaces and the other as reference light, and an optical delay amount that reflects the reference light and is movable so as to change the optical path length of the reference light. Variable means, when the reflected light from each interface of the subject of the probe light and the reflected light from the optical delay amount varying means of the reference light are made incident, and the incident timings of the pulses of these both reflected lights are matched. A match pulse generating means for generating a match pulse, and the match pulse generating means of the optical delay amount varying means corresponding to each match pulse when the match pulse corresponding to each of the interfaces is output. An optical interface dimension measuring device comprising an optical dimension calculating means for calculating an optical dimension between each interface of the subject based on the distance between the moving positions. 2. A movable in the optical axis direction between the beam splitter and the subject, which can be adjusted according to the shape of the interface of the subject so that the probe light is vertically incident on the interface. 2. An optical interfacial dimension measuring apparatus according to claim 1, further comprising: a condensing direction adjusting lens system. 3. The optical system according to claim 1, wherein a focusing lens capable of focusing the probe light on an interface of the subject is disposed between the beam splitter and the subject. Interface dimension measuring device. 4. The beam splitter is a polarization beam splitter, and λ / 4 is included in both round-trip optical paths of light reflected by the polarization beam splitter among the probe light and the reference light.
An optical phase plate is provided, and a reflection unit that reflects one of the reflected light from the subject of the probe light and the reflected light from the optical delay amount varying unit of the reference light in the same direction as the traveling direction of the other. 4. The optical interfacial dimension measuring apparatus according to claim 1, wherein the optical interfacial dimension measuring apparatus is provided. 5. The beam splitter is a polarization beam splitter, and λ is provided in both round-trip optical paths of both the probe light and the reference light.
/ 4 optical phase plate is arranged so that both the reflected light of the probe light from the subject and the reflected light of the reference light from the optical delay amount varying means return to the polarization beam splitter. The optical interfacial dimension measuring device according to any one of claims 1 to 3. 6. A pulsed light output means, and a high reflection that reflects most of the pulsed light from the pulsed light output means as probe light to the subject and transmits the rest of the pulsed light as reference light. A beam splitter at least partially coated with a film, a λ / 4 optical phase plate arranged in both optical paths of the probe light between the beam splitter and the subject, the beam splitter and the λ / 4 is arranged in the optical path of the probe light between the optical phase plates, transmits the probe light from the beam splitter, reflects the reflected light of the probe light from the subject, and reflects the reflected light from the subject. And a polarization beam splitter capable of avoiding incidence on a portion provided with the highly reflective film, and a variable optical delay amount that reflects the reference light and is movable so as to change the optical path length of the reference light. Stage, when the reflected light from each interface of the subject of the probe light and the reflected light from the optical delay amount varying means of the reference light are incident, when the incident timing of the pulse of these both reflected light is matched. Matching pulse generating means for generating a matching pulse, and movement of the optical delay amount varying means corresponding to each matching pulse when a matching pulse corresponding to each of the interfaces is output from the matching pulse generating means. An optical interface dimension measuring device comprising an optical dimension calculating means for calculating an optical dimension between each interface of the subject based on a position interval.