Light diffraction element and optical computing system

Abstract

The present invention realizes a light diffraction element, which can output signal light representing information before operation in addition to signal light representing information after operation. The light diffraction element (1) is composed of a plurality of units. In each unit of the light diffraction element (1), the thickness or refractive index of a first region (C1) transmitting a first polarized light component (X polarized light component) is set independently of each other, and the thickness or refractive index of a second region (C2) transmitting a second polarized light component (Y polarized light component) having a polarization direction different from that of the first polarized light component is the same.

Description

Technical Field

[0001] The present invention relates to an optical diffraction element for performing optical calculations and also to an optical calculation system having such an optical diffraction element. Background Art

[0002] A known optical diffraction element is designed to have a plurality of micro-units with independently set refractive indices, so that the light passing through each micro-unit interferes with each other, thereby optically performing a predetermined operation. The optical operation performed using the optical diffraction element is faster and consumes less power than the electrical operation performed 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 as an intermediate layer of such an optical neural network, for example.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: U.S. Patent No. 7847225 Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] Sometimes, in an operation, it is necessary to refer to both the information before the operation and the information after the operation. For example, a defect extraction operation is an example of such an operation, and the defect extraction operation extracts the defects of the subject from the image, and by synthesizing the image after the operation with the image before the operation, it is possible to obtain an image that allows the inspector to easily visually confirm what defects are in what part of the subject. However, the output light of the existing optical diffraction element only includes the signal light after the operation, and does not include the signal light before the operation. Therefore, the existing optical diffraction element is not suitable for operations that require reference to both the information before the operation and the information after the operation.

[0008] One aspect of the present invention has been made in view of the above-mentioned problem, and an object thereof is to realize a light diffraction element capable of outputting signal light representing information before calculation in addition to signal light representing information after calculation.

[0009] (II) Technical solution

[0010] The optical diffraction element of one embodiment of the present invention is an optical diffraction element composed of a plurality of units. In the optical diffraction element of embodiment 1 of the present invention, the thickness or refractive index of the first region transmitting the first polarized light component in each unit is set independently of each other, and the thickness or refractive index of the second region transmitting the second polarized light component having a polarization direction different from that of the first polarized light component in each unit is the same.

[0011] An optical computing system according to one embodiment of the present invention comprises: the above-mentioned optical diffraction element; a light emitting device which outputs signal light input to the optical diffraction element; and a light receiving device which detects a first polarization component and a second polarization component of the signal light output from the optical diffraction element in a non-discriminatory manner.

[0012] An optical computing system according to one embodiment of the present invention comprises: the above-mentioned optical diffraction element; a light-emitting device that outputs signal light input to the optical diffraction element; a first light-receiving device that detects a first polarization component of the signal light output from the optical diffraction element; and a second light-receiving device that detects a second polarization component of the signal light output from the optical diffraction element.

[0013] (III) Beneficial effects

[0014] According to one aspect of the present invention, a light diffraction element can be realized that can output a signal light representing information before calculation in addition to a signal light representing information after calculation. In addition, according to one aspect of the present invention, an optical calculation system having such a light diffraction element can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a top view showing the structure of a light diffraction element according to one embodiment of the present invention.

[0016] Figure 2 Yes Figure 1 An enlarged perspective view of a portion of the light diffraction element shown.

[0017] Figure 3 Yes means have Figure 1 A three-dimensional diagram of the main structure of the first optical computing system of the optical diffraction element shown.

[0018] Figure 4 Yes means have Figure 1 A three-dimensional diagram of the main structure of the second optical computing system of the light diffraction element shown. DETAILED DESCRIPTION

[0019] (Structure of light diffraction element)

[0020] Reference Figure 1 and Figure 2 The structure of the light diffraction element 1 according to one embodiment of the present invention will be described. Figure 1 It is a top view of the light diffraction element 1. Figure 2 A portion of the light diffraction element 1 (in Figure 1 The enlarged stereogram of the part surrounded by the dotted line in the figure.

[0021] The optical diffraction element 1 is a flat optical diffraction element, which is composed of a plurality of micro units (an example of a "unit" in the claims). Here, a "micro unit" refers to a unit whose unit size is less than 10 μm, for example. In addition, a "unit size" refers to the square root of the unit area. For example, when the top view of the micro unit is a square, the so-called unit size is the length of one side of the unit. The lower limit of the unit size is not particularly limited, for example, it is 1 nm.

[0022] Figure 1 The illustrated light diffraction element 1 is composed of 12×12 micro cells arranged in a matrix. The plan view shape of each micro cell is a 1 μm×1 μm square, and the plan view shape of the light diffraction element 1 is a 12 μm×12 μm square.

[0023] Each micro unit includes: a first region C1, which selectively transmits the first polarized light component contained in the signal light; and a second region C2, which selectively transmits the second polarized light component contained in the signal light. In each micro unit, the thickness or refractive index of the first region C1 is set independently of each other. Thus, the phase change amount of the first polarized light component when passing through each micro unit is set independently of each other. On the other hand, in each micro unit, the thickness or refractive index of the second region C2 is set to be the same. Thus, the phase conversion amount of the second polarized light component passing through each micro unit is set to be the same. Therefore, the optical diffraction element 1 selectively acts on the first polarized light component of the signal light. That is, the optical diffraction element 1 performs a predetermined optical operation by interfering only the first polarized light components of the signal light passing through each micro unit. Therefore, the first polarized light component of the optical signal output from the optical diffraction element 1 is an optical signal representing the information after the operation, and the second polarized light component of the signal light output from the optical diffraction element 1 is an optical signal representing the information before the operation. Here, “selectively transmits the first polarized light component” and “selectively acts on the first polarized light component”, in other words, means “the transmittance of the first polarized light component is higher than the transmittance of the second polarized light component”. Also, “selectively transmits the second polarized light component”, in other words, means “the transmittance of the second polarized light component is higher than the transmittance of the first polarized light component”.

[0024] In addition, the first polarized light component (polarized light component on which the optical diffraction element 1 acts) and the second polarized light component (polarized light component on which the optical diffraction element 1 does not work) can be polarized light components with different polarization directions. For example, X polarized light (linear polarized light with a polarization plane parallel to the ZX plane) can be used as the first polarized light component, and Y polarized light (linear polarized light with a polarization plane parallel to the YZ plane) can be used as the second polarized light component. Alternatively, right circularly polarized light can be used as the first polarized light component, and left circularly polarized light can be used as the second polarized light component. In the present embodiment, as the optical diffraction element 1, the optical diffraction element of the former mode is used, that is, the optical diffraction element 1 that selectively acts on the X polarized light. In other words, the optical diffraction element 1 whose transmittance of the X polarized light is higher than the transmittance of the Y polarized light is used.

[0025] For example Figure 2 As shown, the first area C1 and the second area C2 of each micro unit of the optical diffraction element 1 that selectively acts on X polarized light can be realized by a column with a polarized light filter disposed on the exit surface. The polarized light filter disposed on the exit surface of the column constituting the first area C1 is a polarized light filter that selectively transmits X polarized light (that is, the transmittance of X polarized light is higher than the transmittance of Y polarized light). The polarized light filter disposed on the exit surface of the column constituting the second area C2 is a polarized light filter that selectively transmits Y polarized light (that is, the transmittance of Y polarized light is higher than the transmittance of X polarized light). Thus, the phase change amount of each micro unit relative to Y polarized light can be made constant, and the phase change amount of each micro unit relative to X polarized light can be set to a value corresponding to the height of the column. That is, the optical diffraction element 1 that selectively acts on X polarized light can be realized. In addition, as the above-mentioned polarized light filter, for example, a metal surface can be used. In addition, the polarization filter may be provided on the incident surface of each column instead of being provided on the emission surface of each column, or may be provided on both the incident surface and the emission surface of each column.

[0026] In addition, the setting of the thickness or refractive index of the first region C1 of each micro unit can be realized by using, for example, machine learning. As a model used in the machine learning, for example, a model can be used that takes the intensity distribution of the signal light input to the optical diffraction element 1 as input and the intensity distribution of the first polarized light component of the signal light output from the optical diffraction element 1 as output, and the model includes the thickness or refractive index of the first region C1 of each micro unit as a parameter.

[0027] (First Optical Computing System)

[0028] If the light diffraction element 1 is used, it is possible to optically realize the operation of deriving the sum signal of the signal before the operation and the signal after the operation. Figure 3 1 is a perspective view showing the main structure of an optical computing system 10A for performing such optical computing.

[0029] The optical calculation system 10A includes a light emitting device 2 and a light receiving device 3 in addition to the light diffraction element 1 .

[0030] The light emitting device 2 is a device for generating signal light input to the optical diffraction element 1. The light emitting device 2 has a plurality of units arranged in a matrix, for example, a two-dimensional display. The units of the light emitting device 2 correspond one to one to the micro units of the optical diffraction element 1. The light output from each unit of the light emitting device 2 includes a first polarized light component and a second polarized light component, and is input to the corresponding micro unit of the optical diffraction element 1. In this embodiment, the traveling direction of the signal light is the positive direction of the Z axis, the first polarized light component is the X polarized light component, and the second polarized light component is the Y polarized light component.

[0031] The light receiving device 3 is a device for detecting the signal light output from the light diffraction element 1. The light receiving device 3 has a plurality of units arranged in a matrix, for example, it is composed of a two-dimensional image sensor. The units of the light receiving device 3 correspond to the micro units of the light diffraction element 1 one by one. The X-polarized light component of the signal light that has passed through each micro unit of the light diffraction element 1 interferes with the X-polarized light component of the signal light that has passed through other micro units of the light diffraction element 1, and is input to each unit of the light receiving device 3. On the other hand, the Y-polarized light component of the signal light that has passed through each micro unit of the light diffraction element 1 does not interfere with the Y-polarized light component of the signal light that has passed through other micro units of the light diffraction element 1, and is input to the unit of the light receiving device 3 corresponding to the micro unit. Each unit of the light receiving device 3 detects the signal light output from the light diffraction element 1 in a manner that does not distinguish between the X-polarized light component and the Y-polarized light component. Therefore, the signal light detected in the light receiving device 3 represents the sum signal of the signal before the operation and the signal after the operation.

[0032] As described above, according to the optical computing system 10A, it is possible to implement optical computing of deriving a sum signal of a signal before computing and a signal after computing using the optical diffraction element 1. As an example, the optical computing system 10A can be appropriately used for defect extraction computing, which extracts defects of a subject from an image. In this case, when the original image is displayed on the light emitting device 2 as a display, a composite image in which a defect image including only the defect extracted from the original image as a subject is superimposed on the original image can be detected using the image sensor, i.e., the light receiving device 3.

[0033] In addition, in the present embodiment, a structure is adopted in which a single optical diffraction element 1 is arranged on the optical path of the light output from the light emitting device 2, and the light transmitted through the optical diffraction element 1 is input to the light receiving device 3, but the present invention is not limited thereto. For example, a structure may also be adopted in which a plurality of optical diffraction elements are arranged on the optical path of the light output from the light emitting device 2, and the light transmitted through the optical diffraction elements is input to the light receiving device 3. Thus, an optical computing system 10A that can sequentially perform a plurality of optical computing operations can be realized. In this case, it is sufficient as long as at least one optical diffraction element 1 that selectively acts on X-polarized light is included in the plurality of optical diffraction elements.

[0034] (Second optical computing system)

[0035] If the light diffraction element 1 is used, it is possible to optically realize the operation of deriving the signal before the operation and the signal after the operation separately. Figure 4 1 is a perspective view showing the main structure of an optical computing system 10B for performing such optical computing.

[0036] The optical calculation system 10B includes, in addition to the light diffraction element 1 , a light emitting device 2 , light receiving devices 3 a and 3 b , a polarization beam splitter 4 , and a reflection mirror 5 .

[0037] The light emitting device 2 is the same device as the light emitting device 2 of the optical computing system 10A. The light emitting device 2 has a plurality of units arranged in a matrix, for example, a two-dimensional display. The units of the light emitting device 2 correspond one to one with the micro units of the optical diffraction element 1. The light output from each unit of the light emitting device 2 includes a first polarized light component and a second polarized light component, and is input to the corresponding micro unit of the optical diffraction element 1. In the present embodiment, the traveling direction of the signal light is the positive direction of the Z axis, the first polarized light component is the X polarized light component, and the second polarized light component is the Y polarized light component.

[0038] The polarization beam splitter 4 is an optical element that transmits the X polarization component of the signal light output from the optical diffraction element 1 and reflects the Y polarization component of the signal light output from the optical diffraction element 1. The X polarization component of the signal light that has transmitted the polarization beam splitter 4 is input to the light receiving device 3a. The Y polarization component of the signal light reflected in the polarization beam splitter 4 is further reflected in the reflector 5 and then input to the light receiving device 3b.

[0039] The light receiving device 3a is a device for detecting the X-polarized light component of the signal light that has passed through the polarized light beam splitter 4. The light receiving device 3a has a plurality of units arranged in a matrix, and is composed of, for example, a two-dimensional image sensor. The units of the light receiving device 3a correspond one to one with the micro units of the light diffraction element 1. The X-polarized light component of the signal light that has passed through each micro unit of the light diffraction element 1 interferes with the X-polarized light component of the signal light that has passed through other micro units of the light diffraction element 1, and is input to each unit of the light receiving device 3. The signal light detected in the light receiving device 3a represents the signal after the operation.

[0040] The light receiving device 3b is a device for detecting the Y polarized light component of the signal light reflected in the polarized light beam splitter 4. The light receiving device 3b has a plurality of units arranged in a matrix, for example, composed of a two-dimensional image sensor. The units of the light receiving device 3a correspond to the micro units of the light diffraction element 1 one by one. The Y polarized light component of the signal light that has passed through each micro unit of the light diffraction element 1 does not interfere with the Y polarized light component of the signal light that has passed through other micro units of the light diffraction element 1, and is input to the unit of the light receiving device 3 corresponding to the micro unit. The signal light detected in the light receiving device 3b represents the signal before the operation.

[0041] As described above, according to the optical computing system 10B, it is possible to implement optical computing for respectively deriving a signal before computing and a signal after computing using the optical diffraction element 1. As an example, the optical computing system 10B can be appropriately used for a defect extraction computing for extracting a defect of a subject from an image. In this case, when the original image is displayed on the display, i.e., the light-emitting device 2, the image sensor, i.e., the light-receiving device 3a, can be used to detect a defect image, which contains only a defect extracted from the original image, with the defect as the subject; and the image sensor, i.e., the light-receiving device 3b, can be used to detect the original image.

[0042] In addition, in the present embodiment, a structure is adopted in which a single optical diffraction element 1 is arranged on the optical path of the light output from the light emitting device 2, and the light transmitted through the optical diffraction element 1 is input to the polarization beam splitter 4, but the present invention is not limited thereto. For example, a structure may also be adopted in which a plurality of optical diffraction elements are arranged on the optical path of the light output from the light emitting device 2, and the light transmitted through these optical diffraction elements is input to the polarization beam splitter 4. Thus, an optical computing system 10B that can sequentially perform a plurality of optical computing operations can be realized. In this case, it is sufficient as long as at least one optical diffraction element 1 that selectively acts on X-polarized light is included in the plurality of optical diffraction elements.

[0043] (Summarize)

[0044] The optical diffraction element of the first embodiment of the present invention is an optical diffraction element composed of a plurality of units. In the optical diffraction element of the first embodiment of the present invention, the thickness or refractive index of the first region transmitting the first polarized light component in each unit is set independently of each other, and the thickness or refractive index of the second region transmitting the second polarized light component having a polarization direction different from that of the first polarized light component in each unit is the same.

[0045] According to the above configuration, it is possible to realize a light diffraction element that can output signal light representing information after calculation as a first polarized light component and can output information before calculation as a second polarized light component.

[0046] In the optical diffraction element of mode 2 of the present invention, the structure adopted is: on the basis of the structure of mode 1, a predetermined operation is performed by making the first polarized light components of the signal light passing through the first area of ​​each unit interfere with each other, and the first polarized light component of the signal light output from the optical diffraction element represents the information after the operation, and the second polarized light component of the signal light output from the optical diffraction element represents the information before the light operation.

[0047] According to the above configuration, it is possible to realize a light diffraction element that can output signal light representing information after calculation as a first polarized light component and can output information before calculation as a second polarized light component.

[0048] In the optical diffraction element of mode 3 of the present invention, the structure adopted is: on the basis of the structure of mode 1 or 2, the first area of ​​each unit is composed of columns whose heights are independently set, and a polarization filter that selectively transmits the first polarized light component is arranged on the emitting surface or incident surface of the column.

[0049] According to the above structure, it is possible to easily manufacture a light diffraction element that can output signal light representing information after calculation as the first polarized light component and can output information before calculation as the second polarized light component.

[0050] The optical computing system of mode 4 of the present invention comprises: an optical diffraction element of any one of modes 1 to 3; a light-emitting device that outputs signal light input to the optical diffraction element; and a light-receiving device that detects a first polarization component and a second polarization component of the signal light output from the optical diffraction element in a non-discriminatory manner.

[0051] According to the above configuration, it is possible to optically perform a calculation to derive a sum signal of a signal before calculation and a signal after calculation. As an example, it is possible to optically perform a calculation to derive a composite image of an image before calculation and an image after calculation.

[0052] The optical computing system of mode 5 of the present invention comprises: an optical diffraction element of any one of modes 1 to 3; a light-emitting device that outputs signal light input to the optical diffraction element; a first light-receiving device that detects a first polarization component of the signal light output from the optical diffraction element; and a second light-receiving device that detects a second polarization component of the signal light output from the optical diffraction element.

[0053] According to the above configuration, it is possible to optically realize the operation of separately deriving the signal before the operation and the signal after the operation. As an example, it is possible to optically realize the operation of separately deriving the image before the operation and the image after the operation.

[0054] (Appendix)

[0055] The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical solutions disclosed in the above-described embodiments are also included in the technical scope of the present invention.

[0056] In addition, the "optical diffraction element" in this specification is an element that converts an optical signal representing one information (e.g., an image) into an optical signal representing another information (e.g., another image). Therefore, the "optical diffraction element" in this specification can be renamed as an "optical filter", which is the same as the case where an element that converts an electrical signal representing one image into an electrical signal representing another image is called a filter. In addition, the "optical computing system" in this specification is a system that performs optical computing using an optical diffraction element, i.e., an optical filter.

[0057] Description of Reference Numerals

[0058] 1- optical diffraction element; 10A, 10B- optical computing system; 2- light emitting device; 3- light receiving device; 4- polarization beam splitter; 5- reflector.

Claims

1. A light diffraction element, which is composed of a plurality of units, characterized in that: The unit includes: a first region that transmits a first polarized light component; and a second region that transmits a second polarized light component having a polarization direction different from that of the first polarized light component. The thickness or refractive index of the first region in each unit is set independently of each other, and the phase change amount of the first polarized light component when passing through each unit is set independently of each other. The thickness or refractive index of the second region is the same in each unit, and the phase conversion amount of the second polarized light component passing through each unit is set to be the same. By making the first polarized light components of the signal light transmitted through the first region of each unit interfere with each other, a predetermined optical operation is performed. The first polarized light component of the signal light output from the optical diffraction element represents the information after the optical operation, and the second polarized light component of the signal light output from the optical diffraction element represents the information before the optical operation.

2. The light diffraction element according to claim 1, characterized in that: The first region of each unit is composed of pillars whose heights are independently set, and a polarization filter that selectively transmits the first polarized light component is provided on an exit surface or an incident surface of the pillars.

3. An optical computing system, characterized in that: have: The light diffraction element according to claim 1 or 2; a light emitting device that outputs the signal light input to the light diffraction element; and A light receiving device detects the first polarization component and the second polarization component of the signal light output from the light diffraction element in a manner that does not distinguish between them.

4. An optical computing system, characterized in that: have: The light diffraction element according to claim 1 or 2; a light emitting device that outputs the signal light input to the light diffraction element; and a first light receiving device for detecting a first polarized light component of the signal light output from the light diffraction element; as well as The second light receiving device detects a second polarized light component of the signal light output from the light diffraction element.

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