JP2019090771A - Light detector light detection system, and light detection method - Google Patents

Abstract

To provide a light detector with which it is possible to measure the degree of coherence or the phase of light from an object without using a complicated optical system.SOLUTION: A light detector in some embodiment of the present invention comprises: a first shading film including a plurality of first translucent regions and a plurality of first shading regions alternately arranged in at least a first direction; a second shading film including a plurality of second translucent regions, each facing the plurality of first shading regions, and a plurality of second shading regions, each facing the plurality of first translucent regions; a photodetector including a plurality of photodetection cells, each corresponding to the plurality of first shading regions via the plurality of second translucent regions; and an optical coupling layer provided between the first shading film and the second shading film and including a grating which, when light having a prescribed wavelength enters the plurality of first translucent regions, propagates a portion of the light in the first direction and causes it to enter the plurality of photodetection cells.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a light detection device, a light detection system, and a light detection method.

  Light is an electromagnetic wave and is characterized by properties such as polarization and coherence besides wavelength and intensity. For example, Patent Document 1 discloses a light detection device that measures an object using light coherence among the above-described characteristics.

Patent No. 6044862

  The present disclosure provides a light detection device capable of measuring the degree or phase of coherence of transmitted light, reflected light and / or scattered light from an object without using a complicated optical system.

  A light detection device according to one aspect of the present disclosure includes: a first light shielding film including a plurality of first light transmitting regions and a plurality of first light shielding regions alternately arranged in at least a first direction; A second light shielding film including a plurality of second light transmitting regions and a plurality of second light shielding regions alternately arranged in a direction, wherein the plurality of second light transmitting regions are respectively formed on the plurality of first light shielding regions The plurality of second light shielding regions are light detectors including a second light shielding film respectively facing the plurality of first light transmitting regions and a plurality of light detection cells, and the plurality of light detection cells The photodetectors respectively correspond to the plurality of first light shielding regions through the plurality of second light transmitting regions, and a light coupling layer between the first light shielding film and the second light shielding film, When light is incident on the plurality of first light transmitting regions, a portion of the light is transmitted in the first direction. It is, and a light coupling layer comprising a grating to be incident on the plurality of photodetecting cells via the plurality of second light transmitting regions.

  A light detection device according to another aspect of the present disclosure is a light detection device that detects light from an object, and includes a plurality of light transmission regions and a plurality of light shielding regions alternately arranged in at least a first direction. A light-shielding film including the light-shielding film, and a plurality of light-detecting cells, wherein the plurality of light-detecting cells are respectively corresponding to the plurality of light-shielding regions, and between the light-shielding film and the light-detecting device. An optical coupling layer, comprising: a grating for causing a part of the light to propagate in the first direction and causing the light to be incident on the plurality of light detection cells, when the light is incident on the plurality of light transmission regions; A light coupling layer, and light from the object is incident on the light shielding film without being transmitted through a telecentric lens.

  The above general aspects may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium. Alternatively, the present invention may be realized by any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

  According to one aspect of the present disclosure, the degree or phase of coherence of transmitted light, reflected light and / or scattered light from an object can be measured without a complicated optical system.

FIG. 1 is a view schematically showing a light detection system. FIG. 2 is a view schematically showing how scattered light from an object is incident from one light transmitting region in the light detection device and propagates in the light detection device. FIG. 3A is a view schematically showing the arrangement of detection signals when viewed in the plane-perpendicular direction. FIG. 3B is a diagram schematically showing the arrangement of the plurality of first interpolation signals. FIG. 3C is a view schematically showing the arrangement of the plurality of second interpolation signals. FIG. 3D is a diagram schematically showing the arrangement of the plurality of third interpolation signals. FIG. 3E is a diagram for explaining the flow until generation of a P1 self modulation signal. FIG. 4 is a view schematically showing a state in which scattered light from an object is incident from one light transmitting region in the light detection device and propagates in the light detection device. FIG. 5 is a diagram for explaining the wavelength dependency of the input efficiency. FIG. 6A is a view schematically showing a light detection system. FIG. 6B shows a state in which light which is a part of the light scattered in the object is condensed by the condensing lens, is incident from one light transmitting region in the light detection device, and propagates in the light detection device. It is a figure shown typically. FIG. 7A is a cross-sectional view schematically showing the light detection device in the plane along the light incident direction. FIG. 7B is a plan view schematically showing the light shielding film when the light detection device is viewed from the side on which light is incident.

(Findings that formed the basis of this disclosure)
Before describing the embodiments of the present disclosure, the findings underlying the present disclosure will be described.

  FIG. 6A is a view schematically showing the light detection system 200 disclosed by the present inventors in Patent Document 1. As shown in FIG. The light detection system 200 includes a light source 2, a condenser lens 7, a light detection device 13, a control circuit 1, and an arithmetic circuit 14.

  The light source 2 illuminates the object 4 with light 3 of a fixed coherence length. The light source 2 is, for example, a laser device that emits coherent light. The light source 2 may emit light of constant intensity continuously or may emit pulsed light. The wavelength of the light emitted from the light source 2 is arbitrary. When the target 4 is a living body, the wavelength of the light source 2 may be set to, for example, about 650 nm or more and about 950 nm or less. This wavelength range is included in the red to near infrared wavelength range. In this specification, the term "light" is used not only for visible light but also for infrared light.

  When the object 4 is irradiated with light emitted from the light source 2, the condensing lens 7 condenses the scattered light 5 a and 5 A generated on the surface or inside of the object 4. The scattering path of the scattered light 5a is short, and the scattering path of the scattered light 5A is long. The condensed light is imaged as an image 8 b at the image plane position of the condensing lens 7. Corresponding to the image 8b, on the object 4 side of the condenser lens 7, there is a substantial object 8a which is a collection of object points.

  The light detection device 13 is disposed at the image plane position of the condensing lens 7. The light detection device 13 detects the scattered light 5a, 5A collected by the condensing lens 7. The detailed structure of the light detection device 13 will be described later.

  The arithmetic circuit 14 performs arithmetic processing of the signal detected by the light detection device 13. The arithmetic circuit 14 may be an image processing circuit such as a digital signal processor (DSP).

  The control circuit 1 executes, for example, a program recorded in a memory to detect light by the light detection device 13, arithmetic processing by the arithmetic circuit 14, and light emission quantity of the light source 2, lighting timing, continuous lighting time, light emission Control at least one of wavelength and coherence length. The control circuit 1 may be an integrated circuit such as a central processing unit (CPU) or a microcomputer (microcomputer). The control circuit 1 and the arithmetic circuit 14 may be realized by one integrated circuit.

  The light detection system 200 may include a display (not shown) that displays the result of the arithmetic processing of the arithmetic circuit 14.

  In FIG. 6B, light which is a part of the light scattered in the object 4 is collected by the collecting lens 7 and is incident from one light transmitting region 9 a in the light detection device 13, and the light detection device 13 is Is a figure which shows typically a mode that it propagates. In the example shown to FIG. 6B, an example of a mode that light 3, 5, 5s, 6a, 6b, 6d, 6D mentioned later propagates is represented by the arrow. In fact, the distribution of light 3 spreads in a direction perpendicular to the propagation direction. In the example shown in FIG. 6B, when the object 4 is irradiated with the light 3, of the light scattered from the position L and the position R in the object 4, it passes through the diaphragm 7c and enters the light detection device 13. The gray area shows the appearance of light. Actually, light exiting from the position other than the position L and the position R in the object 4 and passing through the diaphragm 7c and entering the light detection device 13 is also present but is omitted. Moreover, although the light which injects into the photodetector 13 from the translucent area | region 9a of that excepting the above exists, it is abbreviate | omitting. Also in the following figures, an example of light propagation is represented by an arrow.

  The object 4 is a scatterer. The light propagating inside the object 4 repeats scattering inside. The condenser lens 7 is formed of a front lens 7a, an aperture stop 7c and a rear lens 7b, and forms a both telecentric lens or an image telecentric lens. Of the light scattered in the object 4, only the light along the optical axis of the lens becomes the light 5 that passes through the diaphragm 7 c and is incident on the light detection device 13. The stray light 5s shifted from the optical axis is blocked by the stop 7c. The light 5 is vertically incident on the light transmitting region 9a.

  FIG. 7A is a cross-sectional view schematically showing the light detection device 13 in the plane along the light incidence direction. FIG. 7B is a plan view schematically showing a light shielding film 9 described later when the light detection device 13 is viewed from the light incident side. In the following description, a coordinate system defined by mutually orthogonal X, Y, and Z axes is used. The cross-sectional view in the XZ plane shown in FIG. 7A includes a region surrounded by a broken line in FIG. 7B. With the cross-sectional structure of FIG. 7A as one unit, the unit structures are periodically arranged in the XY plane. In the following, the in-plane direction means a direction parallel to the XY plane, and the orthogonal direction means a direction parallel to the Z direction.

  The light detection device 13 includes a light detector 10, a light coupling layer 12, and a light shielding film 9 in this order. In the example shown in FIG. 7A, these configurations are stacked in the Z direction. Moreover, in the example shown to FIG. 7A, the light detection apparatus 13 equips the light shielding film 9 with the transparent substrate 9b and the band pass filter 9p in this order.

  The light detector 10 includes a plurality of light detection cells 10 a and 10 A in the in-plane direction of the light detector 10. The photodetector 10 includes, from the light incident side, microlenses 11a and 11A, a transparent film 10c, a metal film 10d such as a wiring, and a photosensitive portion formed of silicon or an organic film or the like. The photosensitive portions in the gaps between the metal films 10d in the in-plane direction correspond to the light detection cells 10a and 10A. The plurality of micro lenses 11a and 11A are arranged such that one micro lens faces one light detection cell 10a or 10A. The light collected by the microlenses 11a and 11A and incident on the gap of the metal film 10d in the in-plane direction is detected by the light detection cells 10a and 10A.

The light coupling layer 12 is disposed on the photodetector 10, and in a direction perpendicular to the plane of the photodetector 10, the first transparent layer 12c, the second transparent layer 12b on the first transparent layer 12c, and the second transparent layer 12c. And a third transparent layer 12a on the transparent layer 12b. The first transparent layer 12c and the third transparent layer 12a are formed of SiO ₂ or the like. The second transparent layer 12 b is formed of Ta ₂ O ₅ or the like. The refractive index of the second transparent layer 12 b is higher than the refractive index of the first transparent layer 12 c and the refractive index of the third transparent layer 12 a. The light coupling layer 12 may have a structure in which the high refractive index transparent layer 12 b and the low refractive index transparent layer 12 c are further repeated in this order. In the example shown in FIG. 7A, a structure repeated a total of six times is shown.

  The high refractive index transparent layer 12b is sandwiched between the low refractive index transparent layers 12c and 12a and functions as a waveguide layer. A linear grating 12d of pitch Λ is formed over the entire surface at the interface between the high refractive index transparent layer 12b and the low refractive index transparent layer 12c and / or between the high refractive index transparent layer 12b and the low refractive index transparent layer 12a. It is formed. The grating vector of the grating is parallel to the X direction in the in-plane direction of the light coupling layer 12. The shape of the cross section of the grating 12 d in the XZ plane is also sequentially transferred to the high refractive index transparent layer 12 b and the low refractive index transparent layer 12 c to be stacked. When the film formation of the transparent layers 12b and 12c has high directivity in the stacking direction, the transferability of the shape can be easily maintained if the cross section of the grating in the XZ plane is S-shaped or V-shaped. The grating 12d may be provided at least in part of the high refractive index transparent layer 12b. By providing the high refractive index transparent layer 12b with the grating 12d, incident light can be coupled to guided light propagating through the high refractive index transparent layer 12b.

  The gap between the light coupling layer 12 and the photodetector 10 may be narrow or in close contact. A transparent medium such as an adhesive may be filled in the gap between the two microlenses 11 a and 11 A and between the light coupling layer 12 and the light detector 10. When the transparent medium is filled, if the refractive index of the constituent material of the microlenses 11a and 11A is sufficiently larger than the refractive index of the transparent medium to be filled, a lens effect can be obtained in the microlenses 11a and 11A.

  The light shielding film 9 has a plurality of light shielding regions 9A and a plurality of light transmitting regions 9a. In the light shielding area 9A, a reflective film is formed, and in the light transmitting area 9a, the reflective film is removed. In the example shown to FIG. 7A, the light shielding area | region 9A and the light transmission area | region 9a are formed by patterning the metal reflective film formed from Al etc. formed into a film on the transparent substrate 9b. The light transmitting region 9a in FIG. 7A corresponds to the light transmitting regions 9a1, 9a2, 9a3, 9a4 and the like in FIG. 7B. The light shielding region 9A in FIG. 7A corresponds to the light shielding regions 9A1, 9A2, 9A3, 9A4 and the like in FIG. 7B. That is, the light shielding regions 9A and the plurality of light transmitting regions 9a are alternately arranged in the X direction and the Y direction. The plurality of light blocking regions 9A respectively face the plurality of light detection cells 10A. The plurality of light transmitting regions 9a respectively face the plurality of light detection cells 10a. As shown in FIG. 7B, the plurality of light shielding regions 9A (9A1 to 9A4) form a checkered pattern. The light shielding regions 9A (9A1 to 9A4) may form a pattern other than the checkered pattern, and may be, for example, a stripe pattern.

The transparent substrate 9 b is disposed on the light incident side of the light shielding film 9 and is formed of a material such as SiO ₂ . The band pass filter 9 p is disposed on the light incident side of the transparent substrate 9 b and selectively transmits only light in the vicinity of the wavelength λ ₀ among the incident light 5.

The light 5 entering the light detection device 13 passes through the band pass filter 9p and the transparent substrate 9b, and reaches the light shielding area 9A and the light transmitting area 9a as the light 6A, 6a. The light 6A is blocked by the light blocking area 9A. The light 6a passes through the light transmitting region 9a, enters the light coupling layer 12, passes through the low refractive index transparent layer 12a, and enters the high refractive index transparent layer 12b. When the following equation (1) is satisfied, guided light 6 b is generated.

  Here, N is the effective refractive index of the guided light 6b. θ is the incident angle with respect to the normal to the incident plane parallel to the XY plane. λ is the wavelength. Λ is the grating pitch. In the example shown in FIG. 7A, light is vertically incident on the incident surface. That is, θ = 0. In this case, the guided light 6 b propagates in the X direction in the XY plane.

  Light transmitted through the high refractive index transparent layer 12 b and incident on the lower layer is incident on all the high refractive index transparent layers 12 b on the lower layer side. As a result, the guided light 6c is generated under the same condition as the equation (1). In practice, guided light is generated in all the high refractive index transparent layers 12b. In the example shown in FIG. 7A, guided light beams 6b and 6c generated in two layers are representatively shown. The guided light 6 c also propagates in the X-direction in the XY plane, similarly to the guided light 6 b.

  The guided light beams 6b and 6c propagate while emitting light in the vertical direction at an angle θ with respect to the normal to the waveguide surface parallel to the XY plane. In the example shown in FIG. 7A, θ = 0. In the emitted light 6B1 and 6C1, the component directed upward is reflected by the light shielding area 9A immediately below the light shielding area 9A, and becomes light 6B2 going downward. The lights 6B1, 6C1 and 6B2 satisfy the formula (1) with respect to the high refractive index transparent layer 12b. Therefore, a part of the light 6B1, 6C1, 6B2 becomes the guided light 6b, 6c again. The guided lights 6b and 6c also generate new radiations 6B1 and 6C1. The above process is repeated.

  As a whole, immediately below the light transmitting region 9a, the component which has not been guided light passes through the light coupling layer 12, enters the micro lens 11a as the transmitted light 6d, and is detected by the light detection cell 10a. In practice, there is also a component that is ultimately emitted after the wave guide and is detected by the light detection cell 10a. Such a component is also a component that did not become guided light. Immediately below the light shielding region 9A, the component that has become guided light is emitted, and enters the micro lens 11A as the emitted light 6D, and is detected by the light detection cell 10A.

  As shown in P0 and P1 shown in FIG. 6B, light branches into the light detection cell 10a immediately below and the left and right light detection cells 10A through the light transmitting region 9a. The branched light is detected by the light detection cells 10a and 10A, respectively. The detected light amounts in the four light detection cells respectively facing the light transmitting regions 9a1, 9a2, 9a3 and 9a4 shown in FIG. 7B are assumed to be q1, q2, q3 and q4, respectively. The detected light amounts in the four light detection cells respectively facing the light shielding regions 9A1, 9A2, 9A3 and 9A4 shown in FIG. 7B are denoted as Q1, Q2, Q3 and Q4, respectively. The former four are the detected light quantities of the light which did not become guided light, and the latter four are the detected light quantities of the light which became guided light.

  The light detection cell immediately below the light transmitting area 9a1 does not detect the light quantity of the light that has become guided light, and the light detection cell immediately below the light shielding area 9A2 does not detect the light quantity of the light that does not turn into the guided light. Here, Q0 = (Q1 + Q2 + Q3 + Q4) / 4 or Q0 = (Q1 + Q2) / 2 is defined as the detected light quantity of the light which has become guided light at the detection position immediately below the light transmitting region 9a1. At the detection position immediately below the light shielding area 9A2, q0 = (q1 + q2 + q3 + q4) / 4 or q0 = (q1 + q2) / 2 is defined as the detected light amount of the light which did not become guided light. That is, in a region where the light shielding region 9A or the light transmitting region 9a is present, an average value of detected light amounts at detection positions immediately below a region adjacent to the region in the X direction and / or Y direction is defined. By applying this definition to all the areas, the detected light quantity of the light which did not become the guided light and the detected light quantity of the light which became the guided light are defined in all the detection areas constituting the photodetector 10 be able to.

  The arithmetic circuit 14 performs, for example, the following arithmetic processes (1) to (3). (1) In all the light detection cells constituting the light detector 10, the detected light amount of the light which did not become the guided light and the detected light amount of the light which became the guided light are defined as described above. (2) Calculate the value of these ratios or the ratio of each light amount to the sum of these light amounts for each light detection cell. (3) Perform calculation processing such as generating an image by assigning a value calculated for each light detection cell to a pixel corresponding to each light detection cell.

  The average value of the detection values in a certain area, the standard deviation value, or the operation value obtained by combining them reflects the distribution of optical constants such as the absorption coefficient and the scattering coefficient inside the object. Therefore, information indicating the internal state of the object can be detected by using the coherence length of the light source or the like as a parameter.

  A detailed description of the light detection device 13 is disclosed in U.S. Patent Application Publication No. 2016/360967 and U.S. Patent Application Publication No. 2017/023410. The entire disclosure content of US Patent Application Publication No. 2016/360967 and US Patent Application Publication No. 2017/023410 is incorporated herein by reference.

  In the above-described light detection device, an expensive optical system such as a telecentric lens is used as the condensing lens 7 in order to make the light vertically incident.

  However, the present inventors have conceived of a light detection device and a light detection system that the object can be measured without using a complicated optical system by further improving the light detection device described above.

  The present disclosure includes the light detection device and the light detection system described in the following items.

[Item 1]
A first light shielding film including a plurality of first light transmitting regions and a plurality of first light shielding regions alternately arranged in at least a first direction;
The second light-shielding film includes a plurality of second light-transmitting regions and a plurality of second light-shielding regions alternately arranged in the at least first direction, the plurality of second light-transmitting regions being the plurality of And a second light shielding film respectively facing the first light shielding region, and the plurality of second light shielding regions respectively facing the plurality of first light transmitting regions;
A photodetector including a plurality of light detection cells, wherein the plurality of light detection cells respectively correspond to the plurality of first light shield regions via the plurality of second light transmission regions;
A light coupling layer between the first light shielding film and the second light shielding film, which propagates part of the light in the first direction when light is incident on the plurality of first light transmitting regions. An optical coupling layer including a grating that is incident on the plurality of light detection cells via the plurality of second light transmission regions;
Light detection device comprising:

[Item 2]
The light coupling layer includes a first dielectric layer, a second dielectric layer on the first dielectric layer, and a third dielectric layer on the second dielectric layer,
The refractive index of the second dielectric layer is higher than the refractive index of the first dielectric layer and the refractive index of the third dielectric layer,
The grating is between the second dielectric layer and the first dielectric layer and / or between the second dielectric layer and the third dielectric layer.
The light detection device according to Item 1.

[Item 3]
In the first light shielding film, the plurality of first light transmitting regions and the plurality of first light shielding regions are alternately arranged in the first direction and a second direction orthogonal to the first direction. ,
In the second light shielding film, the plurality of second light transmitting regions and the plurality of second light shielding regions are alternately arranged in the first and second directions.
The light detection device according to Item 1 or 2.

[Item 4]
A light detection device for detecting light from an object, comprising:
A light shielding film including a plurality of light transmitting regions and a plurality of light shielding regions alternately arranged in at least a first direction;
A light detector including a plurality of light detection cells, wherein the plurality of light detection cells respectively correspond to the plurality of light shielding regions;
A light coupling layer between the light shielding film and the light detector, which causes part of the light to propagate in the first direction when light is incident on the plurality of light transmitting regions, An optical coupling layer including a grating to be incident on the light detection cell;
Equipped with
Light from the object is incident on the light shielding film without being transmitted through a telecentric lens.
Light detection device.

[Item 5]
In the light shielding film, the plurality of light transmitting regions and the plurality of light shielding regions are alternately arranged in the first direction and a second direction orthogonal to the first direction.
The light detection device according to Item 4.

[Item 6]
A light detection device according to item 3 or 5;
An arithmetic circuit,
Equipped with
The arithmetic circuit is
Of the plurality of light detection cells, in the region located between the two light detection cells adjacent in the first direction, from the signals output from the two light detection cells adjacent in the first direction. A plurality of first interpolation signals in a plurality of interpolation areas other than the plurality of light detection cells among planes including the plurality of light detection cells, obtained by calculating the interpolation signal;
Of the plurality of light detection cells, in a region located between the two light detection cells adjacent in the second direction, from the signals output from the two light detection cells adjacent in the second direction. Among the plurality of second interpolation signals in the plurality of interpolation regions obtained by calculating the interpolation signal, and 2 of the plurality of interpolation regions, 2 calculated for two interpolation regions adjacent in the second direction A plurality of the plurality of light detection cells obtained by calculating an interpolation signal of a light detection cell located between the two interpolation areas adjacent in the second direction from one first interpolation signal; Calculate at least one kind of interpolation signal among the three interpolation signals,
A light detection system that performs calculation using a plurality of signals respectively output from the plurality of light detection cells and the at least one type of interpolation signal.

[Item 7]
A light detection method for detecting light from an object by a light detection device, comprising:
The light detection device
A light shielding film including a plurality of light transmitting regions and a plurality of light shielding regions alternately arranged in at least a first direction;
A light detector including a plurality of light detection cells, wherein the plurality of light detection cells respectively correspond to the plurality of light shielding regions;
A light coupling layer between the light shielding film and the light detector, which causes part of the light to propagate in the first direction when light is incident on the plurality of light transmitting regions, An optical coupling layer including a grating to be incident on the light detection cell;
Equipped with
Causing light from the object to be incident on the light shielding film without transmitting light from a telecentric lens;
Light detection method.

  Hereinafter, more specific embodiments of the present disclosure will be described. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. It is noted that the inventors provide the attached drawings and the following description so that those skilled in the art can fully understand the present disclosure, and intend to limit the claimed subject matter by these. Absent. In the following description, components having the same or similar functions are given the same reference numerals.

  Embodiments will be specifically described below with reference to the drawings.

First Embodiment
The configuration in the embodiment of the present disclosure is the same as the configuration in Patent Document 1 except that the condenser lens 7 is not provided and the signal calculation method is different. Therefore, the examples shown in FIGS. 6A, 6B, 7A and 7B are commonly used, the same reference numerals are given to the common elements, and the overlapping description may be omitted.

  FIG. 1 is a view schematically showing a light detection system 100 in the first embodiment.

  The light detection system 100 includes a light source 2, a light detection device 13, a control circuit 1, and an arithmetic circuit 14. The configuration of the light detection system 100 is the same as the configuration shown in FIG. 6B except that the condenser lens 7 is not provided.

  The light source 2 illuminates the object 4 with light 3 of a fixed coherence length. At that time, scattered light 5a, 5A is generated on the surface or inside of the object 4. Of the scattered light 5 a and 5 A, a component perpendicular to the incident surface of the light detection device 13 enters the light detection device 13. A substantial object 8a, which is a collection of object points, exists on the side of the object 4 corresponding to the image 8b formed by the incident light.

  FIG. 2 is a view schematically showing a state in which the scattered light 5 from the object 4 is incident from one light transmitting region 9 a in the light detection device 13 and propagates in the light detection device 13.

  Similar to the example shown in Patent Document 1, the light detection device 13 includes the light detector 10, the light coupling layer 12, and the light shielding film 9 in this order.

  The light shielding film 9 includes a plurality of light transmitting regions 9a and a plurality of light shielding regions 9A alternately arranged at least in the X direction. In the light shielding area 9A, a reflective film is formed, and in the light transmitting area 9a, the reflective film is removed. As shown in FIG. 7B, the light shielding area 9A and the plurality of light transmitting areas 9a may be alternately arranged in the X direction and the Y direction.

  The light detector 10 includes a plurality of light detection cells 10A. The plurality of light detection cells 10A respectively correspond to the plurality of light shielding areas 9A. “The light detection cell 10A corresponds to the light shielding area 9A” means that the light emitted from the portion of the light coupling layer 12 overlapping the light shielding area 9A when viewed from the direction perpendicular to the light shielding film 9 is detected. It means that the cell 10A is in a direct or indirect detection relationship. For example, the emitted light can be detected indirectly via a condenser lens. Unlike the example shown in FIG. 7A, the light detector 10 may not include the plurality of light detection cells 10a respectively corresponding to the plurality of light transmitting regions 9a.

  The light coupling layer 12 is located between the light shielding film 9 and the photodetector 10, and includes a linear grating 12d. When light of a wavelength satisfying Formula (1) is incident on the plurality of light transmitting regions 9a, the linear grating 12d propagates a part of the light in the X direction and causes the light to be incident on the plurality of light detection cells. In addition, the light coupling layer 12 transmits another part of the light incident on the plurality of light transmitting regions 9 a. The configuration of the light coupling layer 12 is the same as that of the light coupling layer 12 in FIG. 7A.

  Next, when light from the object 4 is incident on the light shielding film 9 without transmitting through the telecentric lens, how the light propagates in the light detection device 13 will be described.

  The light incident on the light detection device 13 includes the component of the light 5 vertically incident and the component of the other stray light 5s. The lights 5 and 5s are incident as 6A and 6As in the light shielding area 9A, and are incident as the lights 6a and 6as in the light transmitting area 9a.

  The light 6A, 6As is blocked by the light blocking area 9A. The lights 6 a and 6 as are transmitted through the light transmitting region 9 a and enter the light coupling layer 12. The light 6a incident on the light coupling layer 12 passes through the low refractive index transparent layer 12a and enters the high refractive index transparent layer 12b. If the equation (1) is satisfied, a part of the incident light 6a becomes the guided light 6b, and the remaining becomes the transmitted light 6d. On the other hand, the incident light 6as does not satisfy the equation (1), and becomes the transmitted light 6ds as it is.

  In the example, the light is vertically incident on the incident surface. That is, θ = 0. The guided light 6 b propagates in the X direction in the XY plane. Directly below the region 9A, a part of the guided light 6b is emitted, and is superimposed on the reflection in the light shielding region 9A to become emitted light 6D. All other operations are the same as those in FIG.

  In the example shown in FIG. 2, the light coupling layer 12 has phase and wavelength selectivity. The light 6as having the angle θ and the wavelength λ not satisfying the equation (1) becomes the transmitted light 6ds transmitted through the light coupling layer 12 without being coupled to the guided light 6b. Therefore, the guided light 6 b and the emitted light 6 D are caused only by the component of the light 5 vertically incident among the light incident on the light coupling layer 12. The stray light 5s falls immediately below the light transmitting region 9a. Therefore, if only the emitted light 6D can be detected and analyzed, the component of the stray light 5s can be removed. It is not necessary to use a telecentric lens as the condenser lens 7 as in the prior art. In the light detection method of detecting the light from the object by the light detection device 13, the light from the object can be made incident on the light shielding film 9 without transmitting the telecentric lens.

FIG. 3A is a view schematically showing the arrangement of detection signals when viewed from the direction perpendicular to the surface according to the first embodiment.
On a plane parallel to the XY plane, the white area is an area immediately below the light transmitting area 9a, and the gray area is an area immediately below the light shielding area 9A. P ₀ corresponds to the amount of light detected by the light detection cell 10 a immediately below the light transmitting region 9 a. P ₁ corresponds to the amount of light detected by the light detection cells 10A immediately below the light-shielding region 9A. On a plane parallel to the XY plane, P ₀ and P ₁ are arranged in the order of indices i and j. P ₀ and P ₁ shown in FIG. 3A are signals as detected, and are referred to as “raw signals”. Further, in a plane parallel to the XY plane including the plurality of light detection cells 10A, a plurality of regions other than the plurality of light detection cells 10A will be referred to as "a plurality of interpolation regions". In the example shown in FIG. 3A, the white area is the interpolation area. The plurality of light detection cells 10a may not be disposed in the plurality of interpolation regions.

  In the light detection system 100 shown in FIG. 1, the arithmetic circuit 14 generates a plurality of first interpolation signals, a plurality of second interpolation signals, and a plurality of third signals from the raw signals detected by the plurality of light detection cells 10A. At least one interpolation signal of the interpolation signals is calculated.

FIG. 3B is a diagram schematically showing the arrangement of a plurality of first interpolation signals in a plurality of interpolation regions. The arithmetic circuit 14 obtains a plurality of first interpolation signals in a plurality of interpolation regions as follows. That is, the arithmetic circuit 14 generates a raw signal output from two light detection cells 10A adjacent to each other in the X direction among the plurality of light detection cells 10A between the two light detection cells 10A adjacent to the X direction. Interpolation signals in the area located are calculated. Specifically, the arithmetic circuit 14 uses the following equation (2), two P ₁ signal adjacent in the X direction in FIG. 3A, and generates a P ₁ signal of the right under the light-transmitting region 9a.

FIG. 3C is a diagram schematically showing the arrangement of a plurality of second interpolation signals in a plurality of interpolation regions. The arithmetic circuit 14 obtains a plurality of second interpolation signals in a plurality of interpolation regions as follows. That is, the arithmetic circuit 14 generates a raw signal output from two light detection cells 10A adjacent to each other in the Y direction among the plurality of light detection cells 10A between the two light detection cells 10A adjacent to the Y direction. Interpolation signals in the area located are calculated. Specifically, the arithmetic circuit 14 generates a P ₁ ′ signal immediately below the light transmitting region 9 a from two P ₁ signals adjacent in the Y direction in FIG. 3A using the following equation (3).

FIG. 3D is a view schematically showing the arrangement of the plurality of third interpolation signals in the plurality of light detection cells 10A. The arithmetic circuit 14 obtains a plurality of third interpolation signals in the plurality of light detection cells 10A as follows. That is, the arithmetic circuit 14 detects a position between two interpolation areas adjacent to each other in the Y direction from the two first interpolation signals calculated for two interpolation areas adjacent to each other in the Y direction among the plurality of interpolation areas. The interpolation signal in the light detection cell 10A is calculated. Specifically, the arithmetic circuit 14 generates a P ₁ ′ signal immediately below the light shielding region 9A from two P ₁ signals adjacent in the Y direction in FIG. 3B using Equation (3).

Arithmetic circuit 14, the above interpolation operation, the right under the light-transmitting region 9a, the P _{1 'signal} P ₁ signal and the second interpolated signal of the first interpolation signal, the right under the light-shielding region 9A, raw signals of the P ₁ signal And P ₁ 'signal of the third interpolation signal.

The arithmetic circuit 14 performs an arithmetic operation using the plurality of raw signals respectively output from the plurality of light detection cells 10A and the at least one type of interpolation signal described above. Thereby, information indicating the internal state of the object is generated. By the calculation, for example, in the detection areas, P1 self modulation factor is the value of P ₁ signal to the sum of P ₁ signal and the P _{1 'signal} is calculated. P ₁ signal is a raw signal or the first interpolated signal, P 1 _'signal is the second or third interpolated signal.

FIG. 3E is a diagram for explaining the flow until generation of a P1 self modulation signal. The first row shows detected values of the raw signal surrounded by thick lines in the example shown in FIG. 3A. 2 column represents the first interpolated signal P ₁ obtained from Equation (2). The third row shows the second and third interpolated signals P ₁ ′ obtained from the equation (3). The fourth row shows the degree of P1 self modulation.

  The degree of self-modulation P1 is generated only from the detection signal immediately below the light shielding area 9A. The degree of self-modulation P1 does not include the component of stray light corresponding to the light 6 as in FIG. Therefore, by using the calculation method of this embodiment, it is possible to analyze only the component of the vertically incident light of the scattered light without using the telecentric lens as the condenser lens 7. Furthermore, as in the example shown in Patent Document 1, the average value of the detection values such as the modulation signal, the standard deviation value, or the calculated value between them is a distribution of optical constants such as absorption coefficient and scattering coefficient inside the object. It reflects the situation. Therefore, information indicating the internal state of the object can be detected by using the coherence length of the light source or the like as a parameter.

Second Embodiment
The configuration in the embodiment of the present disclosure is the same as that in the first embodiment except that the configurations of the light coupling layer 12 and the light shielding film 90 described later are different. Therefore, FIGS. 1, 3, 6A, 6B, 7A, and 7B are commonly used, and the same elements are assigned the same reference numerals and detailed explanations thereof will be omitted.

  FIG. 4 is a view schematically showing a state in which the scattered light 5 from the object 4 is incident from one light transmitting region 9 a in the light detection device 13 and propagates in the light detection device 13 in the second embodiment. It is.

  The light detection device 13 includes a light detector 10, a light shielding film 90, a light coupling layer 12, and a light shielding film 9 in this order. The configuration of the light detection device 13 is the same as the configuration in the first embodiment except for the light coupling layer 12 and the light shielding film 90.

  The light shielding film 9 includes a plurality of light transmitting regions 9a and a plurality of light shielding regions 9A alternately arranged at least in the X direction. In the light shielding area 9A, a reflective film is formed, and in the light transmitting area 9a, the reflective film is removed. As shown in FIG. 7B, the light shielding area 9A and the plurality of light transmitting areas 9a may be alternately arranged in the X direction and the Y direction.

  Similar to the light shielding film 9, the light shielding film 90 includes a plurality of light transmitting regions 90a and a plurality of light shielding regions 90A alternately arranged at least in the X direction. In the light shielding area 90A, a reflective film is formed, and in the light transmitting area 90a, the reflective film is removed. The plurality of light transmitting regions 90a respectively oppose the plurality of light shielding regions 9A. The plurality of light shielding regions 90A respectively oppose the plurality of light transmitting regions 9a. The light shielding region 90A and the plurality of light transmitting regions 90a may be alternately arranged in the X direction and the Y direction.

  Specifically, the two light shielding films 9 and 90 are respectively formed on the upper and lower surfaces of the light coupling layer 12. The upper surface is a surface on which light is incident, and the lower surface is a surface on the opposite side. In the light shielding film 9 located on the upper surface side, the light transmitting region 9a and the light shielding region 9A show the same pattern as that of the first embodiment. In the light shielding film 90 located on the lower surface side, the light transmitting region 90a and the light shielding region 90A show a reverse pattern in which the light transmitting region 9a and the light shielding region 9A on the upper surface side are replaced. In any of the light shielding films 9 and 90, the light shielding regions 9A and 90A and the light transmitting regions 9a and 90a are formed by patterning a metal reflection film made of Al or the like.

  The light detector 10 includes a plurality of light detection cells 10A. The plurality of light detection cells 10A correspond to the plurality of light shielding regions 9A via the plurality of light transmitting regions 90a. “The light detection cell 10A corresponds to the light shielding area 9A through the light transmission area 90a” means that the light detection cell 10A directly or indirectly emits light emitted from the light transmission area 90a facing the light shielding area 9A. It means that it is in a relationship to be detected. For example, the emitted light can be detected indirectly via a condenser lens. The light detector 10 may not include the plurality of light detection cells 10a respectively corresponding to the plurality of light transmitting areas 9a via the plurality of light shielding areas 90A.

  The light coupling layer 12 is located between the two light shielding films 9 and 90, and includes a linear grating 12d. When light of a wavelength satisfying Expression (1) is incident on the plurality of light transmitting regions 9a, the linear grating 12d propagates a part of the light in the X direction, and the plurality of light transmitting regions It is incident on the light detection cell.

Specifically, the light coupling layer 12 is disposed on the light detector 10, and in a direction perpendicular to the plane of the light detector 10, the first transparent layer 12c and the second transparent layer on the first transparent layer 12c. 12b and a third transparent layer 12a on the second transparent layer 12b. The first transparent layer 12c and the third transparent layer 12a are formed of SiO ₂ or the like. The second transparent layer 12 b is formed of Ta ₂ O ₅ or the like. The refractive index of the second transparent layer 12 b is higher than the refractive index of the first transparent layer 12 c and the refractive index of the third transparent layer 12 a. A linear grating 12d of pitch Λ is formed over the entire surface at the interface between the high refractive index transparent layer 12b and the low refractive index transparent layer 12c and / or between the high refractive index transparent layer 12b and the low refractive index transparent layer 12a. It is formed. The grating vector of the grating is parallel to the X direction in the in-plane direction of the light coupling layer 12. Unlike the example shown in FIGS. 2 and 7A, the light coupling layer 12 may not have a structure in which the high refractive index transparent layer 12b and the low refractive index transparent layer 12c are further repeated in this order.

  Next, when light from the object 4 is incident on the light shielding film 9 without transmitting through the telecentric lens, how the light propagates in the light detection device 13 will be described.

  The light scattered in the object 4 and incident on the light detection device 13 includes the component of the light 5 vertically incident and the component of the other stray light 5s. The lights 5 and 5s are incident as 6A and 6As in the light shielding area 9A, and are incident as the lights 6a and 6as in the light transmitting area 9a.

  The light 6A, 6As is blocked by the light blocking area 9A. The lights 6 a and 6 as are transmitted through the light transmitting region 9 a and enter the light coupling layer 12. The light 6a incident on the light coupling layer 12 passes through the low refractive index transparent layer 12a and enters the high refractive index transparent layer 12b. If the equation (1) is satisfied, a part of the incident light 6a becomes the guided light 6b, and the remaining becomes the transmitted light 6d. The transmitted light 6d is reflected by the light shielding area 90A to enhance the excitation of the guided light 6b. Directly below the light shielding area 9A, a part of the guided light 6b is emitted, and is overlapped with the reflection in the light shielding area 9A to become the emitted light 6D. On the other hand, the incident light 6as does not satisfy the equation (1), and becomes the transmitted light 6ds as it is. The transmitted light 6ds is reflected by the light shielding area 90A and is emitted as it is regardless of the excitation of the guided light 6b.

FIG. 5 is a diagram for explaining the wavelength dependency of input efficiency in the second embodiment. The input efficiency corresponds to the light quantity ratio of the guided light 6b to the incident light 6a. The incident light is an S wave whose polarization direction is perpendicular to the paper surface. The pitch of the grating is 0.44 μm and the depth is 0.2 μm. The film thickness of the transparent layer 12b formed of the Ta ₂ O ₅ film is 0.34 μm, and the film thickness of the transparent layers 12a and 12c formed of the SiO ₂ film is 1.24 μm. Under this condition, the input efficiency was calculated. As shown in FIG. 5, it can be seen that the input efficiency is about 18% at the maximum when the light shielding region 90A is not present, while the input efficiency is amplified up to 55% three times when the light shielding region 90A is present. .

This embodiment, by the presence of the light-blocking region 90A, it is impossible to detect the signal P ₀ directly below the light transmitting region 9a in Patent Document 1 and the first embodiment. However, if the same calculation method as that of the first embodiment is used, it is possible to calculate a signal such as the P1 self-modulation degree using only the signal immediately below the light shielding region 9A. Therefore, as in the first embodiment, it is possible to remove stray light and extract and analyze only the component of the vertically incident light in the scattered light without using a telecentric lens as the condenser lens 7.

  In the second embodiment, the light shielding film 90 is increased as compared with the first embodiment. Instead, high input efficiency can be obtained even if the high refractive index transparent layer 12 b and the low refractive index transparent layer 12 c are not repeatedly stacked. Thereby, the light detection device 13 can be simplified as the entire structure.

  Therefore, the embodiment of the present disclosure can also analyze only the component of the vertically incident light of the scattered light without using a telecentric lens as the condenser lens 7. Furthermore, as in the example shown in Patent Document 1, the average value of the detected values such as the degree of modulation, the standard deviation value, or the calculated value thereof indicate the distribution of the optical constants such as the absorption coefficient and the scattering coefficient inside the object. It reflects. Therefore, information indicating the internal state of the object can be detected by using the coherence length of the light source or the like as a parameter.

  The present disclosure can detect the state of coherence or phase of transmitted light, reflected light and / or scattered light from an object as in-plane distribution information. For example, the present disclosure can be used to measure biological information such as cerebral blood flow. Further, information indicating the internal state of the object can be analyzed with high accuracy and high resolution by combining with information of light intensity distribution, time division detection method, or a light source with variable coherence length. In particular, imaging techniques that previously had only been an analysis of the light intensity distribution may add a new evaluation axis, the state or phase of the coherence, to provide multifunctionality to the imaging techniques.

100 light detection system 1 control circuit
2 light source
DESCRIPTION OF SYMBOLS 3 light 4 object 5, 5a 5A scattered light 5s 5as 5 As stray light 7 condensing lens 8a object 8b image of a detection surface position 9a 90a light transmitting area 9A 90A light shielding area 10 light detector 11a 11A micro lens 12 light coupling layer 13 light detection device 14 arithmetic circuit

Claims (7)

A first light shielding film including a plurality of first light transmitting regions and a plurality of first light shielding regions alternately arranged in at least a first direction;
The second light-shielding film includes a plurality of second light-transmitting regions and a plurality of second light-shielding regions alternately arranged in the at least first direction, the plurality of second light-transmitting regions being the plurality of And a second light shielding film respectively facing the first light shielding region, and the plurality of second light shielding regions respectively facing the plurality of first light transmitting regions;
A photodetector including a plurality of light detection cells, wherein the plurality of light detection cells respectively correspond to the plurality of first light shield regions via the plurality of second light transmission regions;
A light coupling layer between the first light shielding film and the second light shielding film, which propagates part of the light in the first direction when light is incident on the plurality of first light transmitting regions. An optical coupling layer including a grating that is incident on the plurality of light detection cells via the plurality of second light transmission regions;
Light detection device comprising: The light coupling layer includes a first dielectric layer, a second dielectric layer on the first dielectric layer, and a third dielectric layer on the second dielectric layer,
The refractive index of the second dielectric layer is higher than the refractive index of the first dielectric layer and the refractive index of the third dielectric layer,
The grating is between the second dielectric layer and the first dielectric layer and / or between the second dielectric layer and the third dielectric layer.
The light detection device according to claim 1. In the first light shielding film, the plurality of first light transmitting regions and the plurality of first light shielding regions are alternately arranged in the first direction and a second direction orthogonal to the first direction. ,
In the second light shielding film, the plurality of second light transmitting regions and the plurality of second light shielding regions are alternately arranged in the first and second directions.
The light detection device according to claim 1. A light detection device for detecting light from an object, comprising:
A light shielding film including a plurality of light transmitting regions and a plurality of light shielding regions alternately arranged in at least a first direction;
A light detector including a plurality of light detection cells, wherein the plurality of light detection cells respectively correspond to the plurality of light shielding regions;
A light coupling layer between the light shielding film and the light detector, which causes part of the light to propagate in the first direction when light is incident on the plurality of light transmitting regions, An optical coupling layer including a grating to be incident on the light detection cell;
Equipped with
Light from the object is incident on the light shielding film without being transmitted through a telecentric lens.
Light detection device. In the light shielding film, the plurality of light transmitting regions and the plurality of light shielding regions are alternately arranged in the first direction and a second direction orthogonal to the first direction.
The light detection device according to claim 4. A light detection device according to claim 3 or 5;
An arithmetic circuit,
Equipped with
The arithmetic circuit is
Of the plurality of light detection cells, in the region located between the two light detection cells adjacent in the first direction, from the signals output from the two light detection cells adjacent in the first direction. A plurality of first interpolation signals in a plurality of interpolation areas other than the plurality of light detection cells among planes including the plurality of light detection cells, obtained by calculating the interpolation signal;
Of the plurality of light detection cells, in a region located between the two light detection cells adjacent in the second direction, from the signals output from the two light detection cells adjacent in the second direction. Among the plurality of second interpolation signals in the plurality of interpolation regions obtained by calculating the interpolation signal, and 2 of the plurality of interpolation regions, 2 calculated for two interpolation regions adjacent in the second direction A plurality of the plurality of light detection cells obtained by calculating an interpolation signal of a light detection cell located between the two interpolation areas adjacent in the second direction from one first interpolation signal; Calculate at least one kind of interpolation signal among the three interpolation signals,
A light detection system that performs calculation using a plurality of signals respectively output from the plurality of light detection cells and the at least one type of interpolation signal. A light detection method for detecting light from an object by a light detection device, comprising:
The light detection device
A light shielding film including a plurality of light transmitting regions and a plurality of light shielding regions alternately arranged in at least a first direction;
A light detector including a plurality of light detection cells, wherein the plurality of light detection cells respectively correspond to the plurality of light shielding regions;
A light coupling layer between the light shielding film and the light detector, which causes part of the light to propagate in the first direction when light is incident on the plurality of light transmitting regions, An optical coupling layer including a grating to be incident on the light detection cell;
Equipped with
Causing light from the object to be incident on the light shielding film without transmitting light from a telecentric lens;
Light detection method.

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