Optical diffraction element and method for adjusting position of optical diffraction element

Abstract

Provided is a position adjustment method that enables accurate adjustment of the position of a second optical diffraction element with respect to a first optical diffraction element in an optical arithmetic device which comprises at least the first and second optical diffraction elements. The position adjustment method (S1) includes a step for inputting adjustment signal light to a second position adjustment optical structure (1B2) via a first position adjustment optical structure (1A2), and for adjusting the position of a second optical diffraction element (1B) with respect to a first optical diffraction element (1A) while referring to the adjustment signal light outputted from the second position adjustment optical structure (1B2).

Description

[Technical field]

[0001] The present invention relates to an optical diffraction element having an optical calculation function, and also to a method for adjusting the position of the optical diffraction element in an optical calculation device including such an optical diffraction element. [Background technology]

[0002] There is known an optical diffraction element that has a plurality of microcells with individually set thicknesses, and optically executes a predetermined calculation by making the light transmitted through each microcell interfere with each other. Optical calculations using an optical diffraction element have the advantage of being faster and consuming less power than electrical calculations using a processor. Patent Document 1 discloses an optical neural network having an input layer, an intermediate layer, and an output layer. The above-mentioned optical diffraction element can be used, for example, as the intermediate layer of such an optical neural network. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 7,847,225 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to perform advanced optical calculations, multiple optical diffraction elements are arranged and used so that the output light of the nth optical diffraction element becomes the input light of the n+1th optical diffraction element. In this case, if the position of the n+1th optical diffraction element relative to the nth optical diffraction element is not adjusted with high precision, it becomes impossible to execute a predetermined optical calculation. Therefore, in order to realize an optical calculation device that performs advanced optical calculations, it is necessary to adjust the position of the n+1th optical diffraction element relative to the nth optical diffraction element with extremely high precision.

[0005] One aspect of the present invention has been made in consideration of the above-mentioned problems, and aims to provide a position adjustment method in an optical computing device including at least a first optical diffraction element and a second optical diffraction element, which is capable of precisely adjusting the position of the second optical diffraction element relative to the first optical diffraction element. [Means for solving the problem]

[0006] A position adjustment method according to one aspect of the present invention is a position adjustment method for adjusting a position of the second optical diffraction element relative to the first optical diffraction element in an optical calculation device including a first calculation optical structure formed of a plurality of microcells, a first optical diffraction element having a first position adjustment optical structure formed inside or outside the first calculation optical structure, and a second calculation optical structure formed of a plurality of microcells, and a second optical diffraction element having a second position adjustment optical structure formed inside or outside the second calculation optical structure. The position adjustment method according to aspect 1 of the present invention includes a step of inputting an adjustment signal light to the second position adjustment optical structure via the first position adjustment optical structure, and adjusting the position of the second optical diffraction element relative to the first optical diffraction element while referring to the adjustment signal light output from the second position adjustment optical structure.

[0007] An optical diffraction element according to another aspect of the present invention includes an arithmetic optical structure constituted by a plurality of microcells, and a position adjustment optical structure formed inside or outside the arithmetic optical structure. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a position adjusting method capable of accurately adjusting the position of a second optical diffraction element relative to a first optical diffraction element. [Brief description of the drawings]

[0009] [Figure 1] 1 is a plan view showing a configuration of an optical diffraction element according to an embodiment of the present invention. [Diagram 2] 2 is an enlarged perspective view of a part of an arithmetic optical structure included in the optical diffraction element shown in FIG. 1. [Diagram 3] 1A and 1B are perspective views showing a configuration of an optical calculation device according to an embodiment of the present invention, in which (a) shows a state during a position adjustment process, and (b) shows a state during an optical calculation process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Configuration of the Optical Diffraction Element] The configuration of an optical diffraction element 1 according to one embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a plan view showing the configuration of the optical diffraction element 1.

[0011] 1, the optical diffraction element 1 is a plate-like element having optical transparency, and includes a substrate 10, an arithmetic optical structure 11 formed on a first main surface of the substrate 10, and a position adjustment optical structure 12 formed on the first main surface or the second main surface (the main surface opposite to the first main surface) of the substrate 10. The substrate 10, the arithmetic optical structure 11, and the position adjustment optical structure 12 may each be made of, for example, glass (e.g., quartz glass) or resin (e.g., photocurable resin).

[0012] The position adjustment optical structure 12 is formed inside or outside the calculation optical structure 11. Here, the position adjustment optical structure 12 is formed inside the calculation optical structure 11 means that a part of the calculation optical structure 11 also functions as the position adjustment optical structure 12. In addition, the position adjustment optical structure 12 is formed outside the calculation optical structure 11 means, for example, the following. That is, when the position adjustment optical structure 12 is formed on the first main surface of the substrate 10, it means that the position adjustment optical structure 12 is formed in a region different from the region where the calculation optical structure 11 is formed on the first main surface. In addition, when the position adjustment optical structure 12 is formed on the second main surface of the substrate 10, it means that the position adjustment optical structure 12 is formed so that the region where the calculation optical structure 11 is formed on the first main surface and the orthogonal projection of the region where the position adjustment optical structure 12 is formed on the second main surface onto the first main surface are different regions. FIG. 1 illustrates an optical diffraction element 1 in which the position adjustment optical structure 12 is formed inside the calculation optical structure 11.

[0013] The computing optical structure 11 is an optical structure for performing a predetermined optical calculation. The computing optical structure 11 can be composed of, for example, a plurality of microcells MC each having a thickness or a refractive index set independently of one another. When signal light is input to the computing optical structure 11, the signal light diffracted by each microcell MC interferes with one another to perform a predetermined optical calculation. The intensity distribution of the signal light output from the computing optical structure 11 represents the result of the optical calculation.

[0014] Here, the term "microcell" refers to a cell with a cell size of less than 10 μm, for example. Also, the term "cell size" refers to the square root of the area of ​​the cell. For example, when the shape of the microcell in plan view is a square, the cell size is the length of one side of the cell. The lower limit of the cell size is not particularly limited, but is, for example, 1 nm.

[0015] 1 is composed of 12×12 microcells MC arranged in a matrix. The shape of each microcell MC in plan view is, for example, a 1 μm×1 μm square, and the shape of the calculation optical structure 11 in plan view is, for example, a 12 μm×12 μm square.

[0016] (1) By setting the thickness of each microcell MC independently, or (2) by selecting the refractive index of each microcell MC independently, the phase change amount of light passing through each microcell MC can be set independently. In this embodiment, the method (1) which can be realized by nanoimprinting is adopted. In this case, as shown in FIG. 2, each microcell MC is formed of a rectangular pillar having a square base with the length of each side equal to the cell size. In this case, the phase change amount of light passing through the microcell MC is determined according to the height of this pillar. That is, the phase change amount of light passing through the microcell MC formed of a tall pillar is large, and the phase change amount of light passing through the microcell MC formed of a short pillar is small.

[0017] The thickness or refractive index of each microcell MC can be set by using, for example, machine learning. As a model used in this machine learning, for example, a model in which the intensity distribution of the signal light input to the calculation optical structure 11 is input and the intensity distribution of the signal light output from the calculation optical structure 11 is output, and a model including the thickness or refractive index of each microcell MC as a parameter can be used. Here, the intensity distribution of the signal light input to the calculation optical structure 11 refers to, for example, a set of numerical values ​​representing the intensity of the signal light input to each microcell MC constituting the calculation optical structure 11. Also, the intensity distribution of the signal light output from the calculation optical structure 11 refers to, for example, a set of numerical values ​​representing the intensity of the signal light input to each microcell constituting the calculation optical structure of another optical diffraction element arranged at the rear of the optical diffraction element 1, or a set of numerical values ​​representing the intensity of the signal light input to each cell of a light receiving device (for example, a two-dimensional image sensor) arranged at the rear of the optical diffraction element 1.

[0018] The position adjustment optical structure 12 is an optical structure for adjusting the position of the optical diffraction element 1 relative to other optical diffraction elements arranged in front of or behind the optical diffraction element 1. The position adjustment optical structure 12 can be composed of, for example, a plurality of microcells MC' each having a thickness, a refractive index, or a transmittance set independently of one another.

[0019] For example, the position adjustment optical structure 12 can be used to form an optical image having a specific intensity distribution on the position adjustment optical structure of another optical diffraction element arranged in a stage subsequent to the optical diffraction element 1. Such a position adjustment optical structure 12 can be realized, for example, by setting the thickness of each microcell MC' so that the position adjustment optical structure 12 functions equivalently to a condenser lens having a specific shape.

[0020] Alternatively, the position adjustment optical structure 12 may be used to change the intensity distribution of an optical image formed by a position adjustment optical structure of another optical diffraction element arranged in front of the optical diffraction element 1, depending on the position of the optical diffraction element 1 relative to the other optical diffraction element. Such a position adjustment optical structure 12 can be realized, for example, by setting the transmittance of each microcell MC' so that the position adjustment optical structure 12 functions equivalently to a mask having a specific shape.

[0021] Incidentally, the configuration in which the position adjustment optical structure 12 is provided inside the calculation optical structure 11 has the disadvantage that the calculation contents of the calculation optical structure 11 are restricted, but has the advantage that the optical diffraction element 1 can be easily miniaturized. However, by providing the position adjustment optical structure 12 in the peripheral portion of the calculation optical structure 11 that is rarely used for optical calculation (for example, in any of the four corners of the calculation optical structure 11 when the planar shape of the calculation optical structure 11 is rectangular), it is possible to sufficiently reduce the restriction on the calculation contents of the calculation optical structure 11. On the other hand, the configuration in which the position adjustment optical structure 12 is provided outside the calculation optical structure 11 has the disadvantage that it is difficult to miniaturize the optical diffraction element 1, but has the advantage that there are no restrictions on the calculation contents of the calculation optical structure 11.

[0022] [Configuration of the optical computing device and flow of the optical computing method] The configuration of an optical arithmetic device 2 according to one embodiment of the present invention and the flow of an optical arithmetic method using the optical arithmetic device 2 will be described with reference to Fig. 3. (a) and (b) of Fig. 3 are perspective views showing the configuration of the optical arithmetic device 2, respectively.

[0023] 3, the optical computing device 2 includes a first optical diffraction element 1A and a second optical diffraction element 1B disposed after the first optical diffraction element 1A. These two optical diffraction elements 1A and 1B are an example of the optical diffraction element 1 described above.

[0024] The first optical diffraction element 1A includes a first optical structure for position adjustment 1A2 inside a first optical structure for calculation 1A1. The second optical diffraction element 1B includes a second optical structure for position adjustment 1B2 inside a second optical structure for calculation 1B1.

[0025] The optical calculation method includes a position adjustment step S1 (one example of the "position adjustment method" described in the claims) and an optical calculation step S2. As shown in FIG. 3(a), the position adjustment step S1 is a step of inputting an adjustment signal light having a specific intensity distribution to the second position adjustment optical structure 1B2 via the first position adjustment optical structure 1A2, and adjusting the position of the second optical diffraction element 1B with respect to the first optical diffraction element 1A while referring to the adjustment signal light output from the second position adjustment optical structure 1B2. The optical calculation step S2 is a step of inputting an operation signal light having an intensity distribution representing an input signal to the second operation optical structure 1B1 via the first operation optical structure 1A1, and acquiring the intensity distribution of the signal light output from the second operation optical structure 1B1 as an intensity distribution representing an output signal (operation result). The optical calculation step S2 is performed after the position adjustment step S1. The wavelength of the adjustment signal light may be the same as or different from the wavelength of the operation signal light.

[0026] In the position adjustment step S1, the first position adjustment optical structure 1A2 is used to form an optical image having a specific intensity distribution on the second position adjustment optical structure 1B2 when an adjustment signal light having a specific intensity distribution is input. The second position adjustment optical structure 1B2 is used to change the intensity distribution of the optical image formed by the first position adjustment optical structure 1A2 according to the position of the second optical diffraction element 1B relative to the first optical diffraction element 1A. By adjusting the position of the second optical diffraction element 1B relative to the first optical diffraction element 1A so that the intensity distribution of the optical image detected by an image sensor arranged after the second position adjustment optical structure 1B2 coincides with a predetermined intensity distribution, the position of the second optical diffraction element 1B relative to the first optical diffraction element 1A can be optimized.

[0027] In this embodiment, the first position adjustment optical structure 1A2 functions as a condenser lens that condenses the adjustment light on the center of the second position adjustment optical structure 1B2. In addition, in this embodiment, the second position adjustment optical structure 1B2 functions as a mask that transmits the adjustment light incident on the center and blocks (absorbs or reflects) the adjustment light incident on the peripheral portion. Therefore, when the position of the second optical diffraction element 1B is deviated from the appropriate position, the intensity of the adjustment light transmitted through the second position adjustment optical structure 1B2 decreases. In addition, diffracted light is generated in the direction in which the position of the second optical diffraction element 1B is deviated from the appropriate position. Therefore, by monitoring the intensity distribution of the adjustment light transmitted through the second position adjustment optical structure 1B2, it is possible to specify in which direction and to what extent the second optical diffraction element 1B has deviated. Note that, when the wavelength of the adjustment signal light and the wavelength of the calculation signal light are different, it is preferable that the microcell that functions as a mask in the second position adjustment optical structure 1B2 blocks the adjustment signal light and transmits the calculation signal light. This makes it possible to reduce the constraints imposed on the computation content of the second computing optical structure.

[0028] Note that the first optical diffraction element 1A may be further provided with a position adjustment optical structure equivalent to the first position adjustment optical structure 1A2, and the second optical diffraction element 1B may be further provided with a position adjustment optical structure equivalent to the second position adjustment optical structure 1B2. This makes it possible to adjust not only the translational positional deviation of the second optical diffraction element 1B relative to the first optical diffraction element 1A, but also the angular deviation in the rotational direction of the second optical diffraction element 1B relative to the first optical diffraction element 1A.

[0029] The above-mentioned position adjustment step S1 may be performed by a manufacturer before shipping the optical calculation device 2 as a product, or may be performed by a user after shipping the optical calculation device 2 as a product.

[0030] 〔summary〕 A position adjustment method according to a first aspect of the present invention is a position adjustment method for adjusting a position of the second optical diffraction element relative to the first optical diffraction element in an optical calculation device including a first calculation optical structure formed of a plurality of microcells, a first optical diffraction element having a first position adjustment optical structure formed inside or outside the first calculation optical structure, and a second calculation optical structure formed of a plurality of microcells, and a second optical diffraction element having a second position adjustment optical structure formed inside or outside the second calculation optical structure. The position adjustment method according to the first aspect of the present invention includes a step of inputting an adjustment signal light to the second position adjustment optical structure via the first position adjustment optical structure, and adjusting the position of the second optical diffraction element relative to the first optical diffraction element while referring to the adjustment signal light output from the second position adjustment optical structure.

[0031] According to the above configuration, the position of the second optical diffraction element with respect to the first optical diffraction element can be adjusted with high precision.

[0032] In the position adjustment method according to aspect 2 of the present invention, in addition to the configuration of aspect 1, the first position adjustment optical structure forms an optical image having a specific intensity distribution on the second position adjustment optical structure, and the second position adjustment optical structure changes the intensity distribution of the optical image formed by the first position adjustment optical structure depending on the position of the second optical diffraction element relative to the first optical diffraction element.

[0033] According to the above configuration, the position of the second optical diffraction element relative to the first optical diffraction element can be adjusted with even greater accuracy.

[0034] In the position adjustment method according to aspect 3 of the present invention, in addition to the configuration of aspect 2, the second position adjustment optical structure is a microcell that functions as a mask for blocking adjustment signal light and includes a microcell that transmits calculation signal light.

[0035] According to the above configuration, it is possible to sufficiently reduce the constraints imposed on the calculation contents of the second calculating optical structure.

[0036] In the position adjustment method according to aspect 4 of the present invention, in addition to the configuration of any one of aspects 1 to 3, the first position adjustment optical structure is formed inside the first calculation optical structure, and the second position adjustment optical structure is formed inside the second calculation optical structure.

[0037] According to the above configuration, the first optical diffraction element and the second optical diffraction element can be easily reduced in size.

[0038] In the position adjustment method of aspect 5 of the present invention, in addition to the configuration of aspect 4, the first position adjustment optical structure is formed on the periphery of the first calculation optical structure, and the second position adjustment optical structure is formed on the periphery of the second calculation optical structure.

[0039] According to the above configuration, it is possible to sufficiently reduce the constraints imposed on the calculation contents of the first optical diffraction element and the second optical diffraction element.

[0040] The optical diffraction element according to a sixth aspect of the present invention includes a calculation optical structure constituted by a plurality of microcells, and a position adjustment optical structure formed inside or outside the calculation optical structure.

[0041] According to the above configuration, it is possible to realize an optical diffraction element whose position relative to another optical diffraction element arranged in the preceding or succeeding stage can be adjusted with high precision and which can be easily miniaturized.

[0042] The optical diffraction element according to the seventh aspect of the present invention includes at least two optical diffraction elements according to the sixth aspect of the present invention.

[0043] According to the above configuration, the position of one optical diffraction element relative to the other optical diffraction element can be adjusted with high precision by using the position adjusting optical structure provided on each of the two optical diffraction elements.

[0044] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the above-described embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0045] 1 Optical Diffraction Element 11 Optical structure for calculation MC Micro Cell 12 Optical structure for position adjustment MC' Microcell 2 Optical calculation device 1A First Optical Diffraction Element 1A1 First computing optical structure 1A2 First position adjustment optical structure 1B Second optical diffraction element 1B1 Second computing optical structure 1B2 Second optical structure for position adjustment S1 Position adjustment process S2 Optical computing process

Claims

1. In an optical computing device including a first optical diffraction element having a first computing optical structure constituted by a plurality of microcells and a first position adjustment optical structure formed inside the first computing optical structure, and a second optical diffraction element having a second computing optical structure constituted by a plurality of microcells and a second optical diffraction element having a second position adjustment optical structure formed inside the second computing optical structure, a position adjustment method for adjusting a position of the second optical diffraction element with respect to the first optical diffraction element, comprising: a step of inputting an adjustment signal light to the second position adjustment optical structure via the first position adjustment optical structure, and adjusting a position of the second optical diffraction element with respect to the first optical diffraction element while referring to the adjustment signal light output from the second position adjustment optical structure. A position adjustment method comprising:

2. the first position adjustment optical structure forms an optical image having a specific intensity distribution on the second position adjustment optical structure, and the second position adjustment optical structure changes the intensity distribution of the optical image formed by the first position adjustment optical structure in accordance with a position of the second optical diffraction element with respect to the first optical diffraction element.

2. The position adjustment method according to claim 1.

3. the second position adjustment optical structure includes a microcell that functions as a mask for blocking the adjustment signal light and transmits the calculation signal light; 3. The position adjustment method according to claim 2.

4. the first position adjustment optical structure is formed on a peripheral portion inside the first calculation optical structure, and the second position adjustment optical structure is formed on a peripheral portion inside the second calculation optical structure; 2. The position adjustment method according to claim 1.

5. A computing optical structure composed of a plurality of microcells; and a position adjustment optical structure formed inside the calculation optical structure. An optical diffraction element comprising:

6. a first optical diffraction element having a first calculation optical structure constituted by a plurality of microcells and a first position adjustment optical structure formed inside the first calculation optical structure, and a second optical diffraction element having a second calculation optical structure constituted by a plurality of microcells and a second position adjustment optical structure formed inside the second calculation optical structure, the first optical diffraction element is disposed in front of or behind the second optical diffraction element, the first position adjustment optical structure and the second position adjustment optical structure overlap, and the first calculation optical structure and the second calculation optical structure overlap; An optical computing device comprising:

7. a first optical diffraction element having a first calculation optical structure constituted by a plurality of microcells and a first position adjustment optical structure formed inside the first calculation optical structure, and a second optical diffraction element having a second calculation optical structure constituted by a plurality of microcells and a second position adjustment optical structure formed inside the second calculation optical structure, an optical arithmetic device characterized in that the first optical diffraction element and the second optical diffraction element are arranged to input adjustment signal light to the second position adjustment optical structure via the first position adjustment optical structure, and to input calculation signal light to the second calculation optical structure via the first calculation optical structure.

Images