JPS60213802A - Optical apparatus - Google Patents

Abstract

PURPOSE:To adjust body light and reference light on a BSO so that the body light forms the hologram of the body without fail, by providing a light shielding block, which shields the reference light, a light-path converting mirror for adjusting the body light and a projecting screen for adjusting the body light. CONSTITUTION:A supporting post 25 with a guide 25 is positioned at a lower place. Reference light is shielded by a block 21. When body light 13 is reflected by a body to be measured 19 and transmitted through a BSO15, the light is reflected by a light-path converting mirror 22 and the image of the BSO is projected on a projecting screen 23. When the body light is not applied to the BSO15, the image of the BSO15 is not projected on the projecting screen 23. When the projecting screen 23 is observed from the back side, the deviation of the light path of the body light 13 in this optical apparatus can be determined. The relative positions of the optical apparatus and the body to be measured 19 is adjusted in the direction so that the deviation is made small. Thus the body light 13 can be made to input in the BSO15 without fail. The body light and the reference light can be adjusted on the BSO so that the hologram of the body 13, whose image is reflected, is formed without fail.

Description

DETAILED DESCRIPTION OF THE INVENTION (7) Technical Field The present invention relates to an optical device that can be applied to various measurements using holography technology.

For example, it is used to measure vibrations in tires, machine tools, etc.

It can also be used to measure deformation of IC boards, mirrors, etc.

(a) Prior art and its problems Holography can be used to measure vibrations and deformation of objects, but conventional holography techniques have had a number of drawbacks.

Most methods that use photographic plates as holographic recording materials have the advantage of high resolution, but
Development and fixing are required. For this reason, real-time performance is lacking. Also, unless the photographic plate is returned to the same position as when the hologram was exposed, the holography will not be reproduced well.

There are such difficulties.

It is conceivable to use thermoplastic as a holographic recording material. Thermoplastic is a resin that exhibits plasticity when heated and solidifies when cooled. When combined with a photoconductive material, the action of electric charge creates unevenness proportional to the transmittance of the image, thereby storing the image. If heat is applied, the records will be erased. Recording and erasing can be repeated. Real-time image processing is possible without the need for processing such as development or fixing. However, those using thermoplastics have poor durability. It is sensitive to moisture and can be reused no more than 100 times. Inferior in terms of lifespan and stability.

Conventional holography devices have drawbacks not only in the light-sensitive material but also in the configuration of the optical system.

The optical system requires mirrors and lenses, and these optical systems are mechanically fixed on a large vibration isolation table. For this reason, a holder is required to fix the mirror and lens, making the installation large.Furthermore, even if the mirror is positioned correctly, the fixing screw may become loose.

Mirrors and lenses may be displaced. Since the mirrors and lenses are large, the optical path length is also long, making it easy for the optical axis to become misaligned. As described above, there were also problems with the reliability and stability of the optical system.

Furthermore, in order to complete the holography measurement device, it is necessary to incorporate a recording light source, a reproduction light source, and a TV camera for capturing a reproduced image into the device, which results in an extremely large size of the device.

Since the recording light source must be a laser that generates coherent light with a short wavelength, an argon laser is used, for example. This is because it is a laser that can continuously emit visible light and has the highest output.

However, it has poor electrical-to-optical conversion efficiency and is a large light source.
There is also a need for cooling.

In this way, conventional optical devices using holography are
It was an extremely large device, lacked real-time performance, and had many problems such as low reliability of the optical system.

(1) Purpose The present invention aims at providing a holographic optical device that is compact, capable of real-time processing, and has a highly reliable optical system.

B) Structure FIG. 1 shows an example of the structure of the holographic optical device of the present invention. Here, one optical element is provided on the substrate 20.

+i''k:'I The single mode fiber 1 multiplexes and transmits light from an externally provided recording light source and a reproducing light source to this optical device. An argon laser is used as the recording light source. The wavelength is 488. nm. As the reproduction light, He-No laser light is used. The wavelength is 688 nm.
It is nm. Since the reproduction light has lower energy, the hologram record is not erased or changed by the reproduction light.

Furthermore, although the recording and reproducing lights are transmitted through the same optical fiber, since their wavelengths are different, they can be separated using a guichroic mirror.

Here, the recording light is light for recording a hologram image of a measurement object onto a photosensitive material, and includes object light and reference light. In the figure, in order to distinguish them, the object light is represented by a diagonal line going downward to the left, and the reference light is represented by a diagonal line going upward to the left. The recording light is shaded both downward to the left and upward to the left.

Reproduction light is indicated by dots.

The collimating lens 2 is provided at a position separated from the output end of the single mode fiber 1 by its focal length.

The collimating lens 2 converts the light emitted from the fiber 1 into parallel light.

The light emitted from the single-mode fiber 1 includes Ugami light and reproduction light. The light made parallel by the collimating lens is separated into reproduction light 11 and recording light 18 by a dichroic mirror 3 provided in front of the collimator lens. Reproducing light is indicated by a broken line arrow, and recording light is indicated by a solid line arrow.

A dichroic mirror has two mirrors with different refractive indexes on the glass surface.
Thin films of a certain thickness are layered alternately.
A mirror that reflects only light of a specific wavelength and transmits light of the remaining wavelength range. This dichroic mirror 3 emits He-Ne laser light (638 nm).
It is designed so that it only reflects light.

The recording light 18 transmitted through the dichroic mirror 3 is
After being reflected by the mirror 4 and having its optical path changed, it enters the beam splitter 6.

The beam splitter 6 reflects a part of the recording light 18 and transmits the rest, forming two beams.

The reflected light becomes object light. This light exits the device and strikes the measuring object 19, by which it is reflected. The reflected light travels to the opposite side, passes through the beam splitter 6, and further passes through the dichroic mirror 7. This object beam enters a BSOl 5 provided as a recording material.

';'aso 15 is bismuth silicon oxide &
(If a DC voltage is applied to a single crystal of 1125 tO2o, it becomes a solid recording material.

The second dichroic mirror 7 through which the object light 13 passes
is the same as the first dichroic mirror 3 mentioned earlier,
Only the reproduction light 11, that is, the helium neon laser light, is reflected, and light of other wavelengths is transmitted.

A portion of the recording light 18 that has passed straight through the beam splitter 6 becomes the reference light 14. The reference light 14 is reflected by the second mirror 5, has its optical path changed, and enters the B5015.

The object beam 13 and the reference beam 14 enter the recording material BSO 15 at a constant narrow angle, and since both beams are coherent beams emitted from the same light source, the two beams interfere, A holographic image corresponding to the shape of the measuring object 19 is formed in the BSOl 5 .

In order to reproduce the four-gram recorded in the BSO 15, reproduction light may be irradiated from the direction of the reference destination. In this case, when viewed from the opposite side of the BSOl 5, a virtual image of the object is seen at the position where the measurement object 19 was.

1.1"tIQ However, in this invention, the direction opposite to the reference light is -1"! BSOL 5 is irradiated with the reproduction light from #.

The light from the He--Ne laser is transmitted through the single mode fiber 1 in the same way as the recording light 2\' light-18.

The light emitted from the single mode fiber 1 is turned into parallel light by the collimating lens 2, and is reflected by the first unidirectional mirror 3. Here, the reproduction light 11 is separated from the recording light 18. The reproduction light 11 is transmitted to the third mirror 8
It is further reflected by the fourth mirror 9 and the fifth mirror 10. The reproduction light 11 reflected by the fifth mirror 10 enters the BSO 15 from the side opposite to the direction of incidence of the reference destination.

The reproduction light 11 passes through the BSOl 5 and is diffracted in a direction opposite to the traveling direction of the object light 13. The reproduction light 11 containing the holographic reproduction image is reflected by the second dichroic mirror 7 and further reflected by the sixth mirror 16. The reflected light forms a holographically reproduced image on the end face of the image fiber 12 by the imaging lens 17. This image is transmitted by image fiber 12. A TV camera is provided at the end of the image fiber 12 to monitor the reproduced image.

Since the reproduction light and recording light have different wavelengths, BSOl 5.
In other words, the direction of the reference beam 14 and the direction of the reproduction beam 11 are not strictly opposite.

, 1 stand, the reproduction light 11' is BSOl
A conjugate real image of the measurement object 19 is created in front of the measurement object 19, that is, at any position on the optical path after being reflected by the second dichroic mirror 7. Bee't of measurement object 19;! If the distance to the F splitter 6 is constant, the position where many real images are present is also constant. This real image is formed on the end face of the image fiber 12 by the imaging lens C7. When the distance between the measurement object 19 and the beam splitter 6 changes, the imaging lens 17 is moved to adjust it.

FIG. 2 shows the overall configuration of an apparatus using the optical apparatus of the present invention.

The inside of the holography optical system 30 is configured as shown in FIG. The light source for recording light is an argon laser 31, and the light source for reproducing light is a helium neon laser 32.

The light from the argon laser 31 is focused by the lens 35 and enters the single mode fiber 1.

The light from the helium neon laser 32 is reflected by the mirrors 34 and 33, focused by the lens 35, and enters the end face of the single mode fiber 1. Single mode fiber 1 transmits two types of light having different wavelengths.

On the other hand, the image fiber 12 is connected to a TV camera 36. This allows the holographically reproduced image to be displayed on the monitor television. Furthermore, it is also possible to store in the memory of the computer the values divided for each pixel.

-11-4 Science, 1% t-Constituting mirror, Gicroic mirror = -J beam splitter is shown in Figures 3(a) and (b).
) The reflective surface 39 may be provided on the diagonal surface of a cube or rectangular parallelepiped in a block shape as shown in (b).
It may also be a triangular prism shape that exposes. Other shapes may be used, but instead of being indirectly fixed with a holder, it is directly adhered to the substrate 20.

Mirrors 4.5.8 from the first mirror to the sixth mirror.
9.10.16 are simply mirrors for changing the optical path, and the selection of the reflection angle and the number of mirror combinations are arbitrary.

With such a configuration, a hologram of the measurement object 19 can be created. In this case, it is necessary that the direction of the object light reflected from the object 19 passes through the BSOl 5. For this reason, it may be necessary to adjust the relative position of the measurement object 19.

This is because such a problem does not occur if the dimensions and shape of the measurement object 19 are substantially constant, but if the dimensions and shapes of the object 19 vary, the object light 13 does not necessarily enter the B5015.

A hologram cannot be created unless the object light enters the BSO 15. When the beam enters a part of the BSO 15, a hologram is recorded only in that part.

! Although it is possible to obtain a holographic reconstructed image from intermediate recording, the diffraction efficiency (amount of diffracted light/amount of reconstructed light) deteriorates, so the image becomes shaky and the S/N ratio deteriorates.

Therefore, in the present invention, a mechanism for adjusting the object light is provided. To check whether the object light 13 is incident on the BSO 15, place a projection screen after the BSOl 5 to block the reference light, and check whether the shadow of the BSO due to the object light is projected on the screen. All you have to do is look into it.

FIG. 4 is a perspective view showing the object light adjustment mechanism provided in the optical device. 26 is a housing.

In order to temporarily block the reference light 14, a light blocking block 21 is provided between the B5015 and the beam splitter 6, which is movable into and out of the reference light path. Furthermore, an optical path conversion mirror 22 for adjusting the object light is provided on an extension of the optical axis of the object light 13 connecting the beam splitter 6 and the BSOl 5.

2 When the object light 13 is reflected by the optical path conversion mirror 22, the projection screen 2 for adjusting the object light is placed on the path of the reflected light.
3 will be provided.

In this example, the light shielding block 21 and the optical path conversion block 22 for adjusting the object light are connected to the connecting member 27 via the support columns 28 and 28, which move up and down at the same time. The connecting member 27 is supported by a guided support 425 in the center. It is movable up and down on a support column 25 with a guide, and can be fixed in an upper position (non-light-shielding) or a lower position (light-shielding) by a stopper 24.

Object light adjustment is performed as follows.

Place the guide support column 25 in the lower position. Rotation is prohibited, and only vertical movement is allowed. Reference light 14 is blocked. The object light 13 does not necessarily pass through the measurement object. If it is transmitted through the BSO 15, it will be reflected by the optical path conversion mirror 22 and projected onto the projection screen 23.
It begins to project the shadow of SO. Object light is BSOl 5
If it does not hit the projection screen 23, the BSOl
The shadow of 5 is not captured. By observing the projection screen 23 from behind, the deviation of the optical path of the object beam 13 inside this optical device can be seen. .

Therefore, the relative positions of the optical device and the measurement/object 19 are adjusted in a direction that reduces the deviation. In this way, the object light 13 can be ensured to be incident on the BSO 15.

In this example, a light shielding block 21 and an optical path conversion mirror 12 are used.
2 can be raised and lowered at the same time. However, there is no requirement that these 11 cities be linked to each other. (1) Recording light and reproducing light are transmitted through a single mode fiber, and the holographic reproduced image is transmitted through an image fiber. Therefore, the holography optical system, light source, and TV camera can be separated. The optical system becomes smaller and easier to handle.

(2) Since mirrors, beam splitters, etc. are adhesively fixed to the substrate, the reliability and stability of the optical system are increased.

(8) Since the directions of incidence of the reproducing light and the recording light on the BSO are different, separation of the two lights becomes particularly easy.

Therefore, a reproduced image with a high S/N ratio can be obtained. (4) In order to ensure that the object beam 13 reflected from the measurement object creates a hologram of the object, the object beam and reference beam are placed on the BSO.
Can be adjusted.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of the optical system of the optical device of the present invention. FIG. 2 is an overall view of the optical device of the present invention. FIG. 3 is a perspective view showing an example of a mirror, a beam splitter, and a dichroic mirror. FIG. 4 is a perspective view of an optical device provided with an object light adjustment mechanism. 1...Single mode fiber 2...
Collimating lens 3...Fourth dichroic mirror 4...
・First mirror 5...Second mirror 6...Beam splitter γ...Second dichroic mirror 8...
・Third mirror 9...Fourth mirror 10...Fifth mirror 11...Reproduction light 12...Image fiber 13... Object Light 14...Reference Light 15...B50 16...Sixth mirror 17...Imaging lens 18...Recording light 19... Measurement object 20... Substrate 21... Light blocking block 22... Optical path converting mirror for object light adjustment 23...
...Projection screen 24 for adjusting object light...
Stopper 25... Guided support column 26... Pillar 27... Connecting member 30... Holography optical system 31... Argon laser 32・・・・・・Helium neon laser 36・・・・・・
・TV camera Figure 4 Figure 2 Police figure 3 (a) (b)

Claims (3)

[Claims] (1) The holography recording light 18 and the holography reproduction light 11 are transmitted from the respective laser light sources to the holography optical system 3
0, a collimating lens 2 that converts the output light of the single mode fiber 1 into parallel light, and a collimating lens 2 that converts the parallel light into recording light 18 and reproduction light 11.
a dichroic mirror 3 that separates the recording beam 18 into an object beam 13 and a reference beam 14; a bismuth silicon oxide (Bi12SiO20) BSO 15 as a holographic recording material; and an object beam reflected by the measurement object 19. 13 and reference light 14 as B
An optical path converting mirror that causes the beams to enter the SO 15 so as to intersect with each other, an optical path converting mirror that changes the optical path of the reproduced light 11 and causes the beam to enter the BSO 15, an image fiber 12 that transmits the reproduced image generated by the reproduced light 11, and a reference beam. a light shielding block 21 that can be moved to a position where it blocks the object light 13; an object light adjustment optical path conversion mirror 22 that can be moved to a position that reflects the object light 13 that has passed through the BSO 15; and an object reflected by the object light adjustment optical path conversion mirror 22. An optical device characterized by having a projection screen 23 for adjusting object light onto which light 13 is projected. (2) The mirror, dichroic mirror, and beam splitter have a cube, rectangular parallelepiped, or triangular prism shape, and the diagonal surface is a reflective surface 39, and these are bonded on the substrate 20. The optical device described in (1). (3) The optical device according to claim (1) or (2), wherein the holographic recording light and the holographic reproducing light are incident on different surfaces of the BSOl 5.