JPS58129414A - Optical device - Google Patents

Abstract

PURPOSE:To eliminate necessity of a surface plate and simplify handling in an optical system for measurement using holography, by molding various optical blocks and base plates for fitting with transparent material. CONSTITUTION:A concavity is formed beforehand on a base plate by etching, etc., and necessary optical blocks 5, 6 and 7 are fixed. After encasing in a package 30 provided with a connector section 33 such as fiber, transparent liquid molding material is filled and solidified to form a mold section 32. By this way, the device is small-sized, light-weighted and simple to handle and reliability is improved, in comparison with a conventional one which are fixed on a surface plate. Loss due to reflection can be reduced by making refractive index of the molding material near to that of glass.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a Fourier transform optical system, an image correlation optical system, a holography optical system, etc., which are small, lightweight, stable, and
It is constructed as an optical device with excellent reliability.

For example, holographic optical devices have a wide range of applications. Techniques such as double exposure holography and real-time holography make it possible to detect, for example, the deformation of an object.

For this purpose, materials capable of real-time recording, such as BSO
A hologram is created by using a BGO element as an image recording material and making object light, which is light reflected from an object, and reference light incident on the recording material at a constant angle.

The deformation measurement method using holography is extremely accurate and makes it possible to detect even minute deformations.

Using holography technology requires a laser device, mirrors to reflect the light from the laser and guide it to an appropriate direction and position, various lenses, and recording materials.

Furthermore, these instruments must be fixed so that their relative positions, relative spacing, and orientation remain strictly unchanged. Even if there is a displacement or vibration of the same magnitude as the wavelength of light, a hologram cannot be created properly.

Conventionally, holographic optical devices have been constructed using a magnetic stand or the like on a heavy and large iron surface plate. The laser is placed on an iron surface plate, and the lens, mirror, recording material, etc. are fixed onto the surface plate using magnetic stands.

The surface plate is elastically supported by tires, springs, etc.
Blocks out the effects of vibration and shock from the surroundings.

Instead of using magnetic stands one-on-one for each device, there are some devices in which lenses, prisms, etc. are housed in a box and this is fixed on a surface plate.

In any case, it had to be constructed on a heavy and large surface plate of about 1009.

Since these holographic optical devices are extremely large optical devices, they are still not practical in terms of weight and size. This is no more than a laboratory experiment.

Furthermore, since the individual optical components are arranged discretely in space, there are still concerns about vibration resistance.

Furthermore, there is a possibility that the optical system may be spatially displaced due to carelessness, which poses problems in terms of stability and reliability as an optical system.

The present invention aims to solve these problems of conventional holography technology.

In the optical system of the present invention, lenses, mirrors, etc. are made of small glass blocks, which are appropriately pasted together to form a block shape, and such blocks and other optical components are photo-etched in corresponding positions in advance. A concave portion is formed, the device is fitted into a certain substrate and adhered, and the entire device is molded with a transparent material.

Hereinafter, the configuration, operation, and effects of the present invention will be explained with reference to drawings showing examples.

FIG. 1 is a perspective view of an optical device according to an embodiment of the present invention, excluding the mold portion, and FIG. 2 is a corresponding structural diagram of the optical device of FIG. 1.

These are BirzSi02o elements (BSO elements)
This is an optical device for measuring deformation by double exposure holography using a recording material, and the configuration shown in FIG. 2 is well known. Separate lasers with different wavelengths are used for writing and reading. For example, an argon laser is used for writing, and a helium neon laser is used for reading.

The double exposure holography configuration diagram shown in FIG. 2 is well known, but will be explained first.

The writing light (a light flux) emitted from the writing laser 1 passes through the single mode fiber F1.

The beam is expanded at the end to form a light beam with a certain degree of spread. This light beam is reflected by the first mirror M1, becomes a broadened b light beam, and enters the /)-fu mirror HM.

Half mirror) 1M divides the b luminous flux into two.

The reflected C light flux illuminates the measurement object O. The measurement object O may be an object of any shape.

The object light (d light flux) reflected from the measurement object 0 carries three-dimensional information regarding the outer shape of the measurement object. d The light flux passes through the half mirror FM, and the dichroic mirror DM
and enters the recording material R perpendicularly.

The dichroic mirror DM is a mirror with selective reactivity, and transmits the light from the writing laser L1, but reflects the light from the reading laser L2.

The recording material is chosen to have real-time characteristics.

For example, BSO element (B112SiOzo), BGO
A recording material is used in which a DC voltage is applied to a single crystal element (BitzGeO2o). Unlike photographic plates, it does not need to be developed and can be read immediately after writing.

On the other hand, the C light flux that has passed through the half mirror HM is reflected by the second mirror M2 and becomes a C light flux. The C light flux functions as a reference light.

To the recording material, object light (d light flux) and reference light (C light flux)
are incident at a certain angle. Writing laser L1
Since the light is coherent light, in the recording material,
Interference fringes corresponding to measurement object 0 are generated. Unlike photographic plates, interference fringes appear as a shift in the distribution of electron clouds.

This is how you can write.

A hologram is created on the recording material R regarding the initial state of the measurement object O. Then, in the post-transformation state, the write operation is performed again while maintaining exactly the same arrangement. By performing two exposures, the holograms of the measurement object 0 before and after deformation are recorded twice into the recording material.

Reading is performed as follows.

The reading laser L2 uses a laser having a longer wavelength than the writing laser, for example, a 1ie-Ne laser.

The readout g light flux passes through the single mode fiber F2, has its beam diameter expanded, and then enters the recording material R from the back side. In other words, the reference light is made to enter the recording material in an almost opposite direction from the extension of the light flux.

Then, the readout light becomes the h light flux, travels in the opposite direction to the d light flux that is the original object light, and forms its real image at the position where the measurement object 0 was.

However, the h light flux is reflected by the dichroic mirror DM on the way, becomes the i light flux, and is further reflected by the third mirror M3.
It becomes a j light flux that passes through the image fiber F3. j luminous flux is observed by a television camera TC.

The light beam j is a reproduction light carrying a double real image of the measurement object O before and after deformation. If a real image has a deformed portion, interference fringes will appear there with a density corresponding to the amount of deformation. By making these interference fringes appear on the screen of the television camera TC, the position and amount of deformation can be directly determined. The processing of the image of measurement object 0 after being imaged by the television camera TC is optional, and instead of directly observing it visually, the interference fringe density may be counted and the amount of dust formed may be automatically calculated.

The above configuration is well known.

In the present invention, mirrors, half mirrors, dichroic mirrors, recording materials, etc. are not combined as discrete components, but prism-shaped glass blocks with vapor-deposited mirror surfaces are bonded together to form blocks that are easy to handle. Also, this block and other necessary lenses,
Mirrors and the like are glued onto a single substrate, and in order to ensure accurate positioning, recesses are previously provided in the substrate at positions where these block members are to be fixed. Furthermore, the entire structure is molded with a transparent material, increasing the stability of the optical system.

FIG. 1 is a perspective view of the optical device of the present invention, excluding the molded part, which is wide and large like a surface plate.
It is not heavy, but is constructed on a thin substrate 1 made of glass, metal, ceramic, etc., which is light and narrow.

FIG. 3 is a perspective view of the substrate 1 only. The flat surface is provided with recesses 2, 3.4. The recess 2 has a shape and dimensions such that the bottom surface of the composite block 5 fits exactly therein. Recess 3
is fitted into the bottom of the mirror block 6. The bottom of the glass block 7 fits into the recess 4.

In this way, recesses are made in advance for all the block members to be fixed to the substrate 1.

For example, photoetching can be used to provide the recesses 2, 3.4. If the substrate is made of glass or metal, the recesses can be precisely formed using photoetching.

However, in the present invention, the method of forming the recess and the depth of the recess are arbitrary. It is also possible to process the recesses mechanically. Further, the substrate can be made of ceramic, but in this case, the recesses can be shaped in advance into the material and then fired.

In FIG. 1, a writing light transmission single mode fiber F1 that transmits the light of the writing laser L1 is connected to a rod lens 8. As shown in FIG. The rod lens 8 is a cylindrical lens with a gradient index of refraction, and has the function of expanding the narrow beam of the laser L1 into a parallel beam with a larger diameter.

A readout light transmission single mode fiber F2 connected to the readout laser L2 is connected to the rod lens 9. A glass block 7 is fixed onto the substrate 1 to support the rod lens 9.

An image fiber F3 for transmitting reproduced light following the television camera TC is connected to a 20mm lens 10. The rod lens 10 forms a real image of the object O to be measured on the end face of the image fiber F3.

The structure of the composite block 5 is made by using elementary blocks made of glass in an appropriate shape, either as they are, or by forming a mirror surface on the boundary surface by metal vapor deposition, and then bonding them together with an adhesive.

The rod lens 8 for introducing the writing light is glued to the end face of the rectangular parallelepiped transparent first elementary block 11.

The writing light beam 3 passes through the first elementary block 11 in the longitudinal direction and enters the second elementary block 12 in the shape of a triangular prism. The third elementary block [3] and the second elementary block 12 are triangular prisms whose bases are isosceles right-angled pentagons, and the diagonal slopes are the first mirrors M l x. That is, the second and third elementary blocks 12,
Metal is deposited on one of the diagonal slopes of 13 to form a mirror, and this is glued together with an epoxy resin adhesive, balsam, or other suitable adhesive.

Immediately below the second elementary block 12 is a fifth block similarly shaped like a triangular prism.
Basic block 15. A sixth elementary block 16 is pasted together with a first mirror Mly interposed therebetween.

The mirrors M l x and M ly are in twisted positions with respect to each other, and together they correspond to the first mirror M1 in FIG.

The fourth elementary block 14 is a rectangular parallelepiped glass block having the same shape and size as the first elementary block. The upper surface is bonded to the first elementary block 11, and the fifth elementary block 15 and the sixth elementary block 16 are bonded to the end surfaces.

The fourth elementary block is only for connecting these elementary blocks. It does not transmit light. Such elementary blocks having only a combining function are also required in order to create a unified composite block 5.

The side surface of the seventh elementary block 17 is attached to the side surface of the fifth elementary block 5. The seventh elementary block 17 and the eighth elementary block 18 have a triangular prism shape, and are combined to form a rectangular parallelepiped. The diagonal slopes are also vapor-deposited with metal, but they are half mirrors (M) rather than total reflection mirrors.

One of the isoplanes of the eighth elementary block 18 constitutes the outer wall surface of the composite block 5, and the extension line of the normal line erected thereto (C
A mirror block 6 exists spatially separated from the composite block 5 (parallel to the light beam).

The object to be measured 0 is located on the extension line of the normal to the plane of the seventh elementary block 17 (parallel to the C light beam).

The b light flux becomes two light fluxes that are divided perpendicularly by the half mirror HM, and the C light flux irradiates the object O to be measured. The C light beam enters the second mirror M2 of the mirror block 6. The d light flux (object light) reflected from the measurement object 0 returns to the seventh elementary block 17, and is now sent to the half mirror [(M
and enters the ninth elementary block 19.

The ninth elementary block 19 is a rectangular parallelepiped, and the first elementary block 11,
It is the same type and size as the fourth elementary block 14. object light d
The light beam passes through the ninth elementary block 19 in the longitudinal direction.

The tenth elementary block 20 is a rectangular parallelepiped glass block pasted on top of the ninth elementary block 19, and although no light is introduced into it, it is laminated to make the structure of the block stable and robust.

On the end face of the ninth elementary block 19, the eleventh elementary block 21
Or pasting. The 11th elementary block 21 and the 12th elementary block 22 have a triangular prism shape, and dichroic mirrors I)M are provided on diagonal slopes by vapor deposition.

A recording material K having real-time characteristics is pasted on the end face of the twelfth elementary block 22. This is a BSO element, BG
For example, use an O element.

A triangular prism-shaped thirteenth element block 23 and fourteenth element block 24 are bonded to the upper surface of the twelfth element block 22 and the end face of the tenth element block 20.

A third mirror M3 is provided on the diagonal slope between the 13th elementary block 23 and the 14th elementary block 24.

The rod lens 10 is bonded to the end face of the fourteenth element block 24.

The reference light (f light flux) and the readout light (g light flux) enter the recording material from opposite sides, but do not necessarily lie along the same straight line. This is because the wavelengths are different. The angle of incidence must be set to satisfy Bragg's condition.

In other words, the ratio of the sine of the angle between the normal to the incident surface of the recording material and the light beam is made equal to the ratio of the wavelength of the light.

Although this is a fairly severe condition, recording material R.

The mirror block M2 and the glass block 7 are all connected to the substrate 1.
Since the recesses 2, 3.4 are provided in advance and the positioning is done using these, there is no need to make fine adjustments after installation.

In this way, the composite glass block 5 is placed on the substrate 1.
, after installing mirror block 6 and glass block 7,
The whole is molded with transparent material.

FIG. 4 is a perspective view of the optical device of the present invention in a ζ-like state.

In this example, the optical device shown in FIG. 1 is packaged in a box-shaped package 3.
0 and then filled with transparent liquid molding material and solidified.

A window 31 is opened in the front of the package 30.
Place the measurement object O in front of it.

Since the substrate 1, composite block 5, mirror block 6, glass block 7, etc. are located inside the mold part 32,
There is no air or the like between these members, and they are connected by a transparent solid layer.

The single mode fibers Fl, F2, image fiber 3, etc. can be taken out from the package individually, but in this example, they are taken out all at once from the connector section 33.

The mold material is preferably transparent, has a coefficient of thermal expansion close to that of the substrate or glass, and has a refractive index close to that of glass.

The purpose of molding is to physically and firmly connect these optical blocks, and to form a glass-like structure.

For example, the glass block is BK7 (with a refractive index of 1.51).
The molding material may be made of, for example, PMMA (polymethyl methacrylate) having a refractive index of 1.49.

Although the optical device of the present invention can be used as shown in FIG.
You may further complete the process by covering it with a lid.

The package 30 and the lid may be transparent or non-transparent;
Any metal, plastic, glass, etc.

However, putting it in a package is not necessarily required for the present invention. Place it in a suitable mold and mold it.
After solidification, it can be removed from the mold and used as is.

The mirrors Ml, . . . can be made by vapor-depositing metal such as aluminum.

Guicroic mirror DM is TiO2, Cen2゜S
It is made by vapor depositing an oxide such as iO.

For example, an Ar laser can be used as the writing laser L1, and a He-Ne laser can be used as the reading laser L2, for example.

In this explanation, an example is given in which the deformation of an object is measured using the double exposure method, but a measurement system using the real-time holography method can also be configured according to the present invention.

The present invention is completely different from the conventional method of constructing a holographic optical device by placing optical equipment on a surface plate made of iron.In the present invention, each optical element is made from a glass block, and these are bonded together to form a composite block. If there is a composite block and a block that cannot be combined with the composite block, each block is placed on a substrate on which four parts have been appropriately provided, and the entire block is then molded, resulting in the following effects.

Moreover, it is lightweight and small.

In terms of only the composite block 5, the rough dimensions are approximately 10 cm x 10 W x 50 M1. Since it is small and light, it is convenient to handle, so it can be used in a wide range of applications.

It can be used for measuring deformation of IC substrates, measuring film thickness in passivation, etc.

In addition to photo etching, the recesses can be made by chemical etching,
It can also be made by plasma etching, ion beam etching, etc.

In this example, there are three recesses, but the number of recesses is arbitrary. It is sufficient to provide the same number of recesses as the number of optical elements (glass blocks) spaced apart from each other.

The present invention can be applied not only to holographic optical devices but also to a wider range of arbitrary optical devices such as Fourier transform optical devices and image correlation optical devices.

Furthermore, the present invention has the advantage of being highly reliable and stable since each optical block is pasted onto the substrate and then molded to make it more solid.

If the refractive index of the mold material is close to the refractive index of the glass, it has the advantage of reducing reflection losses at the mold-glass boundary.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an optical device according to an embodiment of the present invention, with the mold section removed. FIG. 2 is a corresponding configuration diagram of the optical device shown in FIG. 1. FIG. 3 is a perspective view of only the board. FIG. 4 is a perspective view of the optical device placed in a package and molded. 1 Substrate 2.3.4...Concave portion 5...Composite block 6...Mirror block 7...Glass block 8.9.10 Rod lens 11, ~, 24...Element lens Ll... -Writing laser L2...Reading laser Fl...Single mode fiber F2...Single mode fiber F3 - Image fibers M1 to M3...Mirror HM...Half mirror DM...Dichroic Mirror k - Recording material 0 - Measurement object TC - Television camera 3 to J - Light flux d - - Object light f Reference light g - Readout range 30 - Package 31 - Window 32 - Mold section invention Name Yu Nishiwaki Patent applicant Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] A raw glass block, a raw glass block whose predetermined surface is coated with a thin film having a predetermined wavelength transmission characteristic, a composite block formed by adhering lenses, recording materials, etc. to each other, a glass block separated from the composite block, and a pre-prepared glass block. It consists of a substrate that fixes each block body in the recessed part,
An optical device characterized by being entirely made of transparent material.