JPH04125517A - Optical information transmission body - Google Patents

Abstract

PURPOSE:To align, adjust, and fix an optical system extremely easily and simply by constituting optical system components with planes and adhering and fixing them. CONSTITUTION:A lens array plate 8 provided with >=2 microlenses on a common base plate and a lens 9 (2nd lens) whose lens area is >=2 times as large as that of each of the microlenses constituting the lens array are combined, and the light incidence surfaces and projection surfaces of the lens array plate 8 and 2nd lens 9 are all made in plane and joined by adhesion to constitute the integrated optical system. A couple of optical systems which are used basically for matrix arithmetic and light parallel processing arithmetic have their light incidence surfaces and light projection surfaces all formed of planes, and are fixed by adhesion on their planes, so other components can be aligned and fixed by using and fixing the incidence plane surfaces and projection plane surfaces of the lens and microlens array optical system in contact to facilitate the alignment and fixation, thus aligning and fixing the optical system are attained extremely easily.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a very basic optical system configuration for transmitting optical information in the fields of optical information processing, optical computing, etc. . In particular, the present invention relates to an optical system for producing a large number of minute replicas of an input image, which is necessary for performing matrix operations and parallel processing operations using input image information (two-dimensional pattern information).

[Prior Art] Conventionally, as this type of device, the one shown in FIG. 7 is known. In FIG. 7, an input image (1) (letter "A" in the figure) is illuminated by an incoherent illumination light (2), and a relatively large diameter lens (3) placed behind it is illuminated by an incoherent illumination light (2).
) and a large number of microlenses arranged and formed on a single substrate, a microscopic replica image (5) of the input image (1) is created on the rear focal plane of the lens array (4). The same number of lenses are formed as the number of lenses constituting (4).

For example, when the input image (1) is character information and character recognition is performed, each minute replica image (5A).

Transparent reference character pattern masks (6A), (6B), ... are arranged at the positions of (5B)', ..., and detector arrays (7A), (7
B) By arranging . . . , similarity signals between the input character and each reference character pattern can be detected simultaneously and in parallel by the detector array. In addition, parts (5) are shown in the figure for convenience.
), (6), and (7) are shown in separate positions, but in reality, parts (6) and (7) are arranged and fixed in close contact with (5).

[Problems to be Solved by the Invention] However, in the conventional optical system configuration described above, the input image (1), lens (3), lens array (4), reference character pattern mask (6), and detector array For each of (7), x, y, zθ8. θ7. Highly accurate alignment adjustment and fixing of six axes of θ8 is required, making assembly and adjustment extremely difficult.

[Means for solving the problem] A lens array plate with two or more microlenses provided on a common substrate, and a lens array plate with two or more microlenses forming the above lens array.
In addition to combining a lens (second lens) with a lens area that is more than twice as large, the light entrance and exit surfaces of the lens array plate and the second lens are all flat, and the surfaces of the lens array plate and the second lens are connected to each other. They were bonded together to form an integrated optical system.

[Effect]

This is the basis for matrix operations and optical parallel processing operations.
The optical system for obtaining a large number of minute replica images of the input image is
Although it can be configured with one lens and one microlens array, in the present invention, this pair of lens-microlens array optical system is configured with both the light entrance surface and the light exit surface being flat. In addition, since the lens and microlens array are fixed with adhesive between their flat surfaces, alignment and fixation of other parts can be done in close contact using the planes of the entrance and exit surfaces of this lens-microlens array optical system. By fixing it, it becomes easy to fix the alignment of the optical system.

〔Example〕

FIG. 1 shows a reproduction image optical system (2(
1), and Fig. 2 shows an application example of the same optical system.

In FIG. 1, the component (8) is a gradient index rod lens (for example, Selfoc lens manufactured by Nippon Sheet Glass Co., Ltd.).The rod lens (8) is a transparent cylindrical body made of glass or plastic. This lens has a refractive index distribution of approximately square distribution in the radial direction that is rotationally symmetrical with respect to the cylinder axis, and due to the refractive index gradient, light rays are bent inward within the rond, and it acts as a convex lens. The light beam is refracted only by the refractive index gradient within the lens, and both the incident and exit surfaces of the light beam are flat.

Component (9) is a refractive index gradient type flat microlens array. This is a roughly hemispherical refractive index distribution region (the refractive index distribution gradually decreases almost isotropically from the center of the hemisphere toward the periphery) near one surface of a flat transparent substrate made of glass or plastic. It is a microlens array that has a large number of microlenses (distributed). Such a flat microlens array can be fabricated, for example, by internally diffusing ions that increase the refractive index from a limited area on the surface of a glass substrate.

Planar microlens array (hereinafter abbreviated as PML) (
9), the refraction of light rays is done by the refractive index gradient, and PM
Both sides of the L board are flat.

The reproduction image optical system (2 (1)) is a gradient index rod lens (
8) and PML (9). As shown in the figure, the rod lens (8) and PML (9) are adhesively fixed on one plane of each, and the input image (1) is placed closely on the other plane of the rod lens (8) and then imported. When illuminated with coherent illumination (2), a minute replica image (5) of the input image appears on the other surface (the surface that is not fixed with adhesive) of PML (9) for each microlens ( 9A, 9B...).

Figure 3 shows the optical system in Figure 1 (2 (1) is a lens diameter of 3,
Lens length 7.6 pixels, focal length 3mm, torrent lens (8
) and a microlens with a lens diameter of 0.2 m and a focal length of 1 mm (
9A, 9B, . . . ) in a square array with a pitch of 0.4.

A microscopic replica image (5) of the test chart formed on one end surface of the PML when the resolution test chart as the input image (1) is brought into close contact with one end surface of the rod lens (8) and incoherently illuminated with LED. The resolution was measured.

Although the resolution of the image formed by the PML component lens located near the central axis of the rod lens (8) and the image formed by the PML component lens located at the periphery are slightly different (the solid line in Fig. 3 and Dotted line), diameter 3r!
In a minute circular area of m, 21 minute replica images with relatively high resolution were formed as shown in the figure.

The second part shows one application example of the reproduction image optical system according to the present invention.

The front side of the replicated image optical system constructed by adhesively fixing the rod lens (8) and PML (9), that is, the rod lens (8).
A transmissive spatial modulation element (1 (1) (hereinafter referred to as SLM) for displaying a human-powered image (1) is tightly fixed on the incident surface of the SLM (1 (1)). An incoherent light illumination element (11) (for example, a pancaged LED array) is closely fixed.

On the other hand, a reference pattern array (6) is closely fixed to the light exit surface of the PML (9), and a detector array (7) is also closely fixed immediately after the reference pattern array (6).

SLM (1 (1) is, for example, a liquid crystal shutter array sandwiched between two glass substrates, and a reference pattern array (
6) is one in which a Cr film is photolithographically patterned on a glass substrate, for example.

In such a case, the rod lens (8) and PML (9)
) is set to a value that takes into account the thickness of each glass substrate of SLM (1 (1) and reference pattern array (6)), so that the liquid crystal shunter surface that displays the human image (1) can be accurately aligned. Needless to say, the image is to be formed on the reference pattern surface (or detector surface).

With such an optical system, when a character image is displayed by the SLM (1 (1)), the reference pattern array
If a transparent background for each comparison reference character is prepared in (6), comparison signals between the input character and a plurality of reference characters can be detected simultaneously and in parallel by the detector array (7). Also, if the input image is a "vector" and the reference pattern array (6) is a "matrix", then the detector array (
In 7), the product-sum calculation result of the hector and the matrix is output.

In Figure 2, the upper part shows the integrated state, and the lower part shows the disassembled state into each part.
- (11) are used in the form of a unit as shown in the upper figure, with all flat parts tightly fixed together via a transparent adhesive or the like.

Although the present invention has been described above with reference to the illustrated examples, it is not limited thereto, and various modifications can be made.

For example, although FIGS. 1 and 2 show a combination of a rod lens and a PML, a combination of rod lenses having different focal lengths and lens diameters or a combination of PMLs may also be used.

In addition, as an alternative to the rod lens or PML, a lens having a spherical depression on a transparent substrate and filled with a high refractive index material as shown in Fig. 4 may be used. . In addition, in such cases, the transparent substrate with spherical depressions is not filled with a high refractive index material in advance, but the depressions are filled with a high refractive index adhesive when bonding to other parts. Filling and adhesive fixing may be performed simultaneously.

Furthermore, when forming a convex lens using such a spherical recess, it is important to create a refractive index distribution layer in advance near the substrate surface where the refractive index changes in the thickness direction, as shown in Figure 5, to reduce aberrations. It is effective for

In other words, the refractive index near the surface is made slightly lower.

Further, in order to remove noise caused by stray light, it is preferable to apply a light-shielding coating such as a Cr film to areas other than the lenses of the microlens array.

In addition, in order to increase the efficiency of light use, the shape of each microlens in the microlens array does not necessarily have to be circular; instead, each lens pupil is shaped like a hexagon, square, or rectangle so that each lens is closely adjacent to each other. A lens array may also be configured.

Additionally, the input image may be displayed with something like an LED matrix array or semiconductor laser array.

Further, the illumination light does not necessarily have to be incoherent, and may be coherent. For example, a microcopy image of an input image displayed by a transmission type SLM under coherent illumination can be obtained using an optical system as shown in FIG. In this case, a large number of minute replica Fourier transform images of the input image are formed in the plane FT, and parallel processing operations in the spatial frequency plane are also possible.

〔Effect of the invention〕

According to the present invention, all of the optical system components are made of flat surfaces, and the optical distance in the optical axis direction allows the object plane, image plane, etc. to be at appropriate positions simply by closely fixing each component. The alignment of each part is
x, y, z, θ8°θ7. θ2 (The optical axis direction is 2 axes, and the tilt and rotation with respect to the Z axis is θ2. The x and y axes are Z
3 of the 6 axes (axes perpendicular to the axis), x, y, and θ2
Alignment and adjustment become extremely easy, as adjustments only need to be made within the axis, that is, within the plane. In addition, fixing can be accomplished by simply gluing each surface to each other, making it possible to create a stable, highly reliable, compact, integrated optical system with a small number of parts, which does not require special holders as separate parts to fix the parts. .

In this manner, the present invention has made the alignment, adjustment, and fixing of an optical system, which was conventionally extremely complicated, extremely simple, easy, and reliable.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing an embodiment of the present invention, Fig. 2 is a perspective view showing a character recognition device to which the optical system of Fig. 1 is applied, and Fig. 3 shows the actual measurement results of the resolution of the product of the present invention. Graph shown, 4th
The figure is a side cross-sectional view showing the second embodiment of the present invention, Figure 5 is a side cross-sectional view showing another structural example of the flat microlens used in the present invention, and the sixth figure is a side cross-sectional view showing the third embodiment of the present invention. FIG. 7 is a side sectional view showing a conventional image duplication optical system. Input image 2: Incoherent illumination 3: Lens
5: Microscopic replicated image 6: Reference pattern array 7: Detector array 8: Gradient index rod lens 9: Planar microlens array (PML) 10: Transmissive spatial modulation element (SLM) 11: Incoherent illumination element 12: Spherical surface Glass substrate with shaped depressions 13: Glass substrate with spherical depression array 14: High refractive index material 15:
Refractive index distribution area 16: Coherent illumination diagram B ゝ9A Figure diagram A: j, il j1 branch H: (flp/mm) Figure (・-22, ← Liuu 5A'66 A

Claims (9)

[Claims] (1) A lens array plate in which at least two or more microlenses are provided on the same substrate, and at least one lens (second lens) each having a lens area that is at least twice as large as the microlens. The light incident surface and light exit surface of the lens array plate and the second lens are all constructed of flat surfaces, and the lens array plate and the second lens each have a light entrance surface and a light exit surface. An optical information transmitter that is glued and fixed face-to-face. (2) Each microlens of the lens array plate and the second
2. The optical information transmission body according to claim 1, wherein at least one of the lenses is a gradient index lens. (3) Each microlens of the lens array plate and the second
At least one of the lenses is constructed by providing a substantially spherical depression on the surface of a transparent member, filling the depression with a transparent material having a higher refractive index than the transparent member, and making the surface flat. 1. The optical information transmission body according to 1. (4) The optical information transmission body according to claim 3, wherein a refractive index distribution layer having a refractive index gradient in the thickness direction is provided near the surface of the transparent member. (5) Each microlens of the lens array plate and the second
5. At least one of the lenses is configured so that when a parallel beam of light is incident from at least one surface, the incident parallel light is condensed near the other surface. The optical information transmission body described in . (6) The optical information transmission body according to any one of claims 1 to 5, wherein a region of the lens array plate other than each microlens is provided with a light shielding plate or a light shielding coating. (7) The optical information according to any one of claims 1 to 6, wherein each microlens of the lens array plate has at least a part of its lens outer shape in contact with an adjacent microlens. transmission body. (8) The optical information transmission body according to any one of claims 1 to 7, wherein each of the microlenses of the lens array plate includes at least two types of microlenses having different focal lengths. (9) The second lens has a cylindrical outer shape and has an isotropic refractive index distribution in the radial direction with respect to the cylindrical axis. optical information transmission body.