WO2023176636A1

WO2023176636A1 - Imaging device

Info

Publication number: WO2023176636A1
Application number: PCT/JP2023/008829
Authority: WO
Inventors: 磨志橋本谷; 雄介北川
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2022-03-16
Filing date: 2023-03-08
Publication date: 2023-09-21

Abstract

An imaging device (1) comprises: a light source unit that emits light structured into a plurality of two-dimensional light/dark patterns; a light detector (30) that detects light emitted from an object (90) when the object (90) is illuminated with light from the light source unit; and a computation unit (50) that reconstructs a two-dimensional image of the object (90) by performing cross-correlation operation between a signal outputted from the light detector (30) and a corresponding light/dark pattern. The light source unit emits light in a plurality of different bands. The computation unit (50) reconstructs a two-dimensional image for each band.

Description

Imaging device

The present disclosure relates to an imaging device.

Patent Document 1 discloses a wavelength transmission system in which a light source that irradiates a subject with infrared light, infrared detection elements arranged in a two-dimensional array, and a plurality of wavelength transmission filters that transmit different wavelength bands are arranged on a plane. A solid-state imaging device including a filter array is disclosed. The solid-state imaging device disclosed in Patent Document 1 identifies the substance of the object and acquires image information of the object from wavelength information obtained by an infrared detection element.

Japanese Patent Application Publication No. 2016-163125

In the solid-state imaging device disclosed in Patent Document 1, an infrared detection element and a wavelength transmission filter array are integrally formed. In this case, if a defect occurs in even one wavelength band, the entire device may become unusable, and there is a concern that the yield will decrease. Furthermore, in order to be able to detect many wavelength bands, it is necessary to increase the area or reduce the number of pixels. In other words, there is a trade-off between sensor size and spatial resolution.

Therefore, the present disclosure provides an imaging device that can reduce the sensor size while suppressing a decrease in spatial resolution.

An imaging device according to an aspect of the present disclosure includes a light source unit that structures light into a plurality of two-dimensional bright and dark patterns and emits the light, and a light source unit that emits light from the target object when the light from the light source unit is irradiated onto the target object. a photodetector that detects the light emitted by the object; a calculation unit that reconstructs a two-dimensional image of the object by performing a cross-correlation calculation between a signal output from the photodetector and a corresponding brightness pattern; , the light source section emits light in a plurality of different bands, and the calculation section reconstructs the two-dimensional image for each band.

Further, an imaging device according to another aspect of the present disclosure includes a light source unit that emits light, and a plurality of light sources that emit light from the target object when the light from the light source unit is irradiated onto the target object. a structuring means for structuring into a dimensional light-dark pattern; a photodetector for detecting the light structured by the structuring means; and a cross-correlation between a signal output from the photodetector and the corresponding light-dark pattern. a calculation unit that reconstructs a two-dimensional image of the object by performing calculation, the light source unit emits light of a plurality of mutually different bands, and the calculation unit Reconstruct a two-dimensional image.

According to the present disclosure, the sensor size can be reduced while suppressing a decrease in spatial resolution.

FIG. 1 is a diagram showing the configuration of an imaging device according to Embodiment 1. FIG. 2 is a diagram illustrating a two-dimensional image reconstruction method by the imaging device according to the first embodiment. FIG. 3 is a diagram showing the configuration of an imaging device according to a modification of the first embodiment. FIG. 4 is a diagram showing the configuration of an imaging device according to the second embodiment. FIG. 5 is a diagram showing the configuration of an imaging device according to Embodiment 3. FIG. 6 is a diagram illustrating the principle of an imaging device according to Embodiment 3. FIG. 7 is a diagram showing the configuration of an imaging device according to Embodiment 4. FIG. 8 is a diagram showing the configuration of an imaging device according to a modification of the fourth embodiment.

(Summary of this disclosure)
An imaging device according to an aspect of the present disclosure includes a light source unit that structures light into a plurality of two-dimensional bright and dark patterns and emits the light, and a light source unit that emits light from the target object when the light from the light source unit is irradiated onto the target object. a photodetector that detects the light emitted by the object; a calculation unit that reconstructs a two-dimensional image of the object by performing a cross-correlation calculation between a signal output from the photodetector and a corresponding brightness pattern; , the light source section emits light in a plurality of different bands, and the calculation section reconstructs the two-dimensional image for each band.

As a result, the arithmetic unit reconstructs a two-dimensional image by performing a cross-correlation calculation, so a detector with fewer pixels than the number of pixels of the two-dimensional image can be used as a photodetector. That is, the sensor size can be reduced while suppressing a decrease in spatial resolution. For example, a single pixel detector can be used as the photodetector. Furthermore, since a two-dimensional image is reconstructed for each band, it is possible to obtain a distribution of components corresponding to each band. In other words, the imaging device according to this aspect can be effectively used as a small-sized analysis device with high resolution.

Further, for example, the light source unit may include a light source and a structuring means for structuring the light from the light source into the plurality of two-dimensional bright and dark patterns.

Further, for example, the structuring means includes a plurality of optical elements arranged two-dimensionally, and the plurality of optical elements direct incident light in a first direction and a second direction different from the first direction. The photodetector includes a first light receiving element that receives light emitted from the structuring means in the first direction, and a first light receiving element that receives light emitted from the structuring means in the second direction. and a second light receiving element that receives the light.

As a result, signals corresponding to two bright and dark patterns can be obtained simultaneously in one measurement, making it possible to shorten measurement time or reconstruct a high-quality two-dimensional image. Alternatively, noise can be removed by using the difference between signals corresponding to two bright and dark patterns, making it possible to reconstruct a high-quality two-dimensional image.

Also, for example, the structuring means may be a digital mirror device, an active matrix liquid crystal device, or a spatial light modulator.

Thereby, it is possible to easily structure the light, that is, form a two-dimensional light and dark pattern.

Further, for example, the plurality of bands may be included in a wavelength band of 2 μm or more and 10 μm or less.

As a result, by using the mid-infrared band, it can be used for component analysis of a target object or inspection for the presence of foreign substances other than the target object.

Furthermore, for example, the calculation unit may further estimate the chemical composition of the object based on the signal intensity ratio of the two two-dimensional images for each of at least two bands.

This enables detailed component analysis of the target object.

Furthermore, for example, the light emitted from the target object may be reflected light generated when the target object reflects at least a portion of the light from the light source section.

This makes it useful for analyzing objects with low transmittance.

Furthermore, for example, the light emitted from the object may be transmitted light generated when the object transmits at least a portion of the light from the light source section.

This makes it useful for analyzing objects with high transmittance.

Hereinafter, embodiments will be specifically described with reference to the drawings.

Note that all embodiments described below are comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, steps, order of steps, etc. shown in the following embodiments are examples, and do not limit the present disclosure. Further, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims will be described as arbitrary constituent elements.

Furthermore, each figure is a schematic diagram and is not necessarily strictly illustrated. Therefore, for example, the scales and the like in each figure do not necessarily match. Further, in each figure, substantially the same configurations are denoted by the same reference numerals, and overlapping explanations will be omitted or simplified.

(Embodiment 1)
First, the configuration of the imaging device according to Embodiment 1 will be described using FIG. 1. FIG. 1 is a diagram showing the configuration of an imaging device 1 according to the present embodiment.

The imaging device 1 shown in FIG. 1 is a device that images the object 90 by irradiating the object 90 with light. In this embodiment, the imaging device 1 detects reflected light from the object 90 as light emitted from the object 90 when the object 90 is irradiated with light. Since the light irradiated onto the object 90 is absorbed by components contained in the object 90, the intensity of the reflected light from the object 90 changes depending on the amount of light absorbed. The amount of absorption at this time differs for each component included in the target object 90 and for each wavelength band (namely, band) of the irradiated light. Therefore, by irradiating light of a specific band, it is possible to estimate the presence and distribution of components (functional groups) corresponding to the band. Note that in FIG. 1, the path of light emitted from the light source 10, reflected by the object 90, and then reaching the photodetector 30 is schematically represented by a broken line.

The object 90 is, for example, a medicine tablet or powder. The imaging device 1 can be used to detect foreign substances contained in medicine tablets or powder. Note that the object 90 is not limited to a medicine tablet or powder, but may be a food product or an industrial product. Furthermore, the object 90 is not limited to a solid object, and may be a liquid or a gas.

As shown in FIG. 1, the imaging device 1 includes a light source 10, a structuring means 20, a photodetector 30, a control section 40, and a calculation section 50. Further, the imaging device 1 includes a plurality of optical elements 61 to 64 and a half mirror 65.

The light source 10 emits light in a plurality of different bands. The plurality of bands are included in a wavelength band of 2 μm or more and 10 μm or less. For example, the plurality of bands are at least two bands selected from the group of bands shown in Table 1 below.

Table 1 shows the specific wavelength range of each band and the components that can be measured when the light of the band is irradiated. For example, by irradiating the object 90 with band A light and detecting the reflected light from the object 90, the presence and distribution of NH can be estimated. The light source 10 can select any band from the band group shown in Table 1 according to the component to be measured, and can irradiate light of the selected band.

Each band of light is a narrow band of light having a peak wavelength within the wavelength range of the corresponding band. The half-width of light in each band is, for example, shorter than the bandwidth of the band. The light in each band does not substantially contain wavelength components outside the corresponding band.

In this embodiment, the light source 10 emits light for each band in a time-division manner. For example, the light source 10 emits band A light and then emits band B light.

The light source 10 is, for example, an infrared tunable laser such as a quantum cascade (QC) laser. Alternatively, the light source 10 may be a broadband light source and a wavelength selective light source using a grating or the like, or may include a plurality of filters corresponding to each band.

A broadband light source emits light having a predetermined or higher intensity across multiple bands. For example, the broadband light source is an LED (Light Emitting Diode), a halogen lamp, a supercontinuum light source, a superluminescent diode light source, or the like.

The plurality of filters corresponding to each band are bandpass filters that transmit light in the corresponding band and block light in other bands. The light source 10 can emit light in a corresponding band by passing light emitted from a broadband light source through one filter selected from a plurality of filters. The light source 10 can emit light for each band in a time-division manner by switching the selected filter.

The structuring means 20 structures the light from the light source 10 into a plurality of two-dimensional bright and dark patterns. The bright and dark pattern is represented by "bright" and "dark" for each of a plurality of micro regions arranged in an array on a two-dimensional plane. In FIG. 1, the structuring means 20 is a transmission type device, and the transmittance can be changed for each micro region. A micro region with high transmittance is "bright", and a micro region with low transmittance is "dark". In particular, the structuring means 20 is an active matrix liquid crystal device or a spatial light modulator or the like. Note that as the structuring means 20, a reflective device such as a digital mirror device (DMD) may be used. An example of using a digital mirror device will be explained later.

The structuring means 20 switches the plurality of bright and dark patterns in a time-division manner based on the control by the control unit 40. For example, the plurality of bright and dark patterns are randomly generated based on a predetermined algorithm. The number of bright and dark patterns is several hundred or more, but may be several thousand or more, or even tens of thousands or more. The greater the number of bright and dark patterns, the higher the quality of the two-dimensional image to be reconstructed. On the other hand, by reducing the number of bright and dark patterns, the time required for measurement can be shortened.

The number of minute regions corresponds to the number of pixels of the two-dimensional image to be reconstructed. Therefore, by increasing the number of minute regions, a high-definition two-dimensional image can be obtained.

The photodetector 30 detects light emitted from the object 90 when irradiated with light from the light source 10. In this embodiment, the photodetector 30 irradiates the object 90 with structured light by the structuring means 20 and detects the reflected light of the structured light by the object 90. The photodetector 30 outputs a signal according to the intensity of the detected reflected light. The timing at which the photodetector 30 outputs a signal is controlled by the control unit 40 so as to be synchronized with the timing at which the bright/dark pattern is switched. That is, the photodetector 30 outputs a signal according to the intensity of light (specifically, reflected light) emitted from the object 90 for each bright and dark pattern. The signal output from the photodetector 30 can be associated one-to-one with the bright and dark pattern.

The photodetector 30 is, for example, a one-pixel infrared photodetector. As the infrared photodetector, for example, a HgCdTe detector, an InSb detector, or a bolometer can be used.

In this embodiment, a one-pixel (single pixel) detector can be used as the photodetector 30, so the photodetector 30 can be made smaller. Furthermore, since a large light-receiving area for one pixel can be ensured, sensitivity can be increased or the dynamic range can be expanded. Additionally, photodetectors sensitive to the mid-infrared band are generally expensive. As the photodetector 30, a simple and compact detector for one pixel can be used, so that cost reduction can also be achieved.

The control unit 40 performs overall control of the imaging device 1. Specifically, the control section 40 controls the light source 10, the structuring means 20, the photodetector 30, and the calculation section 50. For example, the control unit 40 controls the timing of turning on and turning off the light source 10 and the timing of switching bands. The control unit 40 controls the switching timing of the plurality of bright and dark patterns by the structuring means 20. Further, the control unit 40 controls the output timing of the signal from the photodetector 30 so as to correspond to each of the plurality of bright and dark patterns. Further, the control unit 40 outputs information to the calculation unit 50 to enable association between brightness and darkness patterns and signals, and association with signals for each band.

The calculation unit 50 reconstructs a two-dimensional image of the object 90 by performing a cross-correlation calculation between the signal output from the photodetector 30 and the corresponding brightness/darkness pattern. The calculation unit 50 reconstructs a two-dimensional image for each band. A specific reconstruction method will be explained later.

The control unit 40 and the calculation unit 50 are each realized by, for example, an LSI (Large Scale Integration) that is an integrated circuit (IC). Note that the integrated circuit is not limited to an LSI, and may be a dedicated circuit or a general-purpose processor. For example, the control unit 40 may be a microcontroller. A microcontroller includes, for example, a nonvolatile memory in which a program is stored, a volatile memory that is a temporary storage area for executing the program, an input/output port, a processor that executes the program, and the like. Further, the control unit 40 or the calculation unit 50 may be a programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor in which connections and settings of circuit cells within the LSI can be reconfigured. The functions executed by the control unit 40 or the calculation unit 50 may be realized by software or hardware. The control unit 40 and the calculation unit 50 may use common hardware resources.

The optical elements 61 to 64 and the half mirror 65 are provided to adjust the optical path. Each of the optical elements 61 to 64 controls the optical path by utilizing the difference in refractive index from the light propagation space. Specifically, each of the optical elements 61 to 64 is an element that causes refraction, reflection, dispersion, or scattering. For example, the optical elements 61 to 64 are lenses, diffraction gratings, reflectors, light guides, beam homogenizers, and the like.

The optical element 61 is, for example, a collimator that converts the light emitted from the light source 10 into parallel light. The optical element 62 is a collimator that outputs the light structured by the structuring means 20 as parallel light. The optical element 63 is structured by the structuring means 20 and is a projection lens that irradiates light transmitted through the half mirror 65 toward the object 90 . In this embodiment, optical element 63 is also an objective lens that condenses light (specifically, reflected light) from target object 90. That is, the optical element 63 is used for both the irradiation optical system and the objective optical system. The optical element 64 is a condensing lens that condenses light from the object 90 and reflected by the half mirror 65 onto the photodetector 30.

The half mirror 65 is an optical element that separates the light irradiated onto the object 90 from the light (reflected light) from the object 90. Specifically, the half mirror 65 transmits the light structured by the structuring means 20 and reflects the reflected light from the object 90. By using the half mirror 65, the optical element 63 can be used both as an irradiation optical system and an objective optical system. Since the optical axis of the irradiation optical system and the optical axis of the objective optical system can be made the same, it is possible to increase the collection efficiency of reflected light from the target object 90 and to suppress the intrusion of disturbance light that causes noise. Can be done.

The optical elements 61 to 64 and the half mirror 65 are formed using a suitable material depending on the wavelength of the light to be transmitted. For example, germanium, calcium fluoride, potassium bromide, etc. can be used as a material that transmits light in the mid-infrared band. Alternatively, multilayer films of various dielectrics or metals may be used.

Note that the configuration shown in FIG. 1 is only an example and can be modified as appropriate. For example, the structuring means 20 may be arranged between the light source 10 and the optical element 61 or between the optical element 62 and the half mirror 65. In this case, at least one of the

optical elements

61 and 62 may not be provided.

Furthermore, for example, the irradiation optical system that irradiates light onto the target object 90 and the objective optical system that acquires the reflected light from the target object 90 may be realized by separate optical elements. In this case, the imaging device 1 does not need to include the half mirror 65.

[Reconstruction method]
Next, a method for reconstructing a two-dimensional image by the imaging device 1 will be described using FIG. 2.

FIG. 2 is a diagram showing a two-dimensional image reconstruction method by the imaging device 1 according to the present embodiment.

The calculation unit 50 reconstructs a two-dimensional image using a plurality of bright and dark patterns (also referred to as structured patterns) and signals from the photodetector 30 corresponding to each bright and dark pattern. As shown in FIG. 2, a two-dimensional image is reconstructed by multiplying multiple bright and dark patterns by the signal from the photodetector 30 (cross-correlation calculation) and summing the products for each pattern. Ru.

In other words, reconstruction of a two-dimensional image refers to a plurality of structured patterns generated by the structuring means 20 and irradiated onto the object 90, and images emitted from the object 90 when each structured pattern is irradiated. This refers to mathematically deriving a two-dimensional image (reflectance distribution or transmittance distribution) of the object 90 from the intensity of light.

Reconstruction methods include, for example, a method called ghost imaging and a method called single pixel imaging.

<Ghost imaging>
In ghost imaging, if the signal intensity from the photodetector 30 is b _r , b _r is expressed by the following equation (1).

In equation (1), the subscript r represents the irradiation order of the bright and dark patterns. That is, b _r represents the signal intensity from the photodetector 30 corresponding to the light of the r-th bright and dark pattern. I _r represents the r-th brightness pattern. x and y are two-dimensional coordinates of the light and dark pattern. T(x,y) is the reflectance of the target object 90. Note that, when using transmitted light from the object 90 as in the fourth embodiment and its modifications described later, T(x, y) is the transmittance of the object 90.

In ghost imaging, in order to reconstruct a two-dimensional image of the object 90, a quadratic correlation function expressed by the following equation (2) is defined.

Here, n is the number of bright and dark patterns. <k> is an ensemble average and is expressed by the following equation (3).

G(x, y) in Equation (2) is the average value of intensity changes in all bright and dark patterns at the coordinates (x, y). Therefore, when the number n of bright and dark patterns is sufficiently large, G(x, y) approaches T(x, y), and it becomes possible to consider it as a reconstructed two-dimensional image.

<Single pixel imaging>
In single-pixel imaging, in principle, M linearly independent brightness and darkness patterns are required in order to obtain a two-dimensional image consisting of N pixels. M is, for example, a value greater than or equal to N. Regarding a linearly independent brightness/darkness pattern I(x,y) consisting of N pixels, if the corresponding signal intensity is B and the image of the object 90 is T, the following equation (4) is satisfied.

Since T can be expressed as T(x, y) as a two-dimensional image, equation (4) can be regarded as a matrix operation. That is, equation (4) can be expressed as equation (5) below.

In other words, by using the inverse matrix of the matrix H, the matrix T, that is, the two-dimensional image T(x, y) can be obtained. As the matrix H, for example, a Hadamard matrix is used.

As described above, two methods, ghost imaging and single pixel imaging, have been described as methods for reconstructing a two-dimensional image, but the specific method is not particularly limited as long as a two-dimensional image can be reconstructed. The calculation unit 50 of the imaging device 1 according to the present embodiment performs the above-described reconstruction of the two-dimensional image for each band. As shown in Table 1, the bands correspond to the components to be measured, and the amount of reflected light from the object 90 changes depending on the content of the component. Therefore, a two-dimensional image reconstructed for each band can also be regarded as a two-dimensional distribution of corresponding components.

In the present embodiment, the calculation unit 50 may estimate the chemical composition of the object 90 based on the signal intensity ratio of two two-dimensional images for each of at least two bands. For example, by referring to a database in which signal intensity ratios and chemical compositions are registered in association with each other, the calculation unit 50 calculates the chemical composition of the object 90 that matches or is similar to the signal intensity ratio obtained by measurement. Extract as a composition. The database may be stored in a storage unit included in the calculation unit 50, or may be stored in an external device that can communicate with the imaging device 1.

As described above, in the imaging device 1 according to the present embodiment, a two-dimensional image is reconstructed for each band, so a single pixel detector can be used as the photodetector 30. That is, the sensor size can be reduced while suppressing a decrease in spatial resolution. Furthermore, since a two-dimensional image is reconstructed for each band, it is possible to obtain a distribution of components corresponding to each band. In other words, the imaging device 1 can be effectively used as a small-sized analysis device with high resolution.

[Modified example]
A modification of the first embodiment will be described below with reference to FIG. 3.

FIG. 3 is a diagram showing the configuration of an imaging device 2 according to this modification. As shown in FIG. 3, the imaging device 2 includes a light source section 11 instead of the light source 10 and the structuring means 20, compared to the imaging device 1 shown in FIG.

The light source section 11 structures light into a plurality of two-dimensional bright and dark patterns and emits the light. That is, the light source section 11 has the functions of both the light source 10 and the structuring means 20 described above. Specifically, the light source section 11 includes a plurality of light emitting elements arranged two-dimensionally. Each of the plurality of light emitting elements can be turned on and off independently. A bright and dark pattern is generated by turning on and turning off each light emitting element. For example, the light source section 11 is an LED array having LEDs as light emitting elements.

In this way, even with the imaging device 2 having the light source section 11 in which the light source 10 and the structuring means 20 are integrated, it is possible to reconstruct a two-dimensional image for each band, similarly to the imaging device 1. It can be used for analysis of the object 90, etc.

(Embodiment 2)
Next, Embodiment 2 will be described.

The second embodiment differs from the first embodiment in that the structuring means is placed on the photodetector side. Below, the explanation will focus on the differences from Embodiment 1, and the explanation of the common points will be omitted or simplified.

FIG. 4 is a diagram showing the configuration of the imaging device 101 according to this embodiment. As shown in FIG. 4, the imaging device 101 is different from the imaging device 1 shown in FIG. 1 in the arrangement of the structuring means 20. Specifically, the structuring means 20 is arranged between the half mirror 65 and the optical element 64.

In the present embodiment, the structuring means 20 converts the light emitted from the object 90 (specifically, the reflected light generated by the object 90) into a plurality of two when irradiated with light from the light source 10. Structure into dimensional light-dark patterns. As the structuring means 20, a translucent device such as an active matrix liquid crystal device can be used as in the first embodiment.

Similarly to the first embodiment, the calculation unit 50 reconstructs a two-dimensional image of the object 90 by performing a cross-correlation calculation between the signal output from the photodetector 30 and the corresponding brightness/darkness pattern. A specific reconstruction method may utilize ghost imaging or single pixel imaging. Reconstruction of the two-dimensional image is performed for each band.

In this way, even when the structuring means 20 structures the reflected light from the target object 90, it is possible to reconstruct a two-dimensional image as in the first embodiment. Since the imaging device 101 according to the present embodiment reconstructs a two-dimensional image for each band, a single-pixel detector can be used as the photodetector 30. That is, the sensor size can be reduced while suppressing a decrease in spatial resolution. Further, as in the first embodiment, since a two-dimensional image is reconstructed for each band, a distribution of components corresponding to each band can be obtained. In other words, the imaging device 101 can be effectively used as a small-sized analysis device with high resolution.

(Embodiment 3)
Next, Embodiment 3 will be described.

The third embodiment differs from the second embodiment in that it includes a plurality of photodetectors. Below, the explanation will focus on the differences from Embodiment 2, and the explanation of the common points will be omitted or simplified.

FIG. 5 is a diagram showing the configuration of the imaging device 201 according to this embodiment. The imaging device 201 includes a light source 10, a structuring means 220, two

photodetectors

231 and 232, a control section 240, and a calculation section 250. Further, the imaging device 201 includes optical elements 261 to 265 and a half mirror 266.

The light source 10 is the same as in

Embodiments

1 and 2, and emits light in a plurality of different bands.

The structuring means 220 simultaneously structures the incident light (specifically, the reflected light generated by the object 90) into two bright and dark patterns and outputs the structured light. The two bright and dark patterns are a first bright and dark pattern and a second bright and dark pattern whose brightness is inverted from that of the first bright and dark pattern.

The two light and dark patterns of light are respectively emitted in a first direction and a second direction different from the first direction. The first direction is an output direction for making light incident on the photodetector 231. In the example shown in FIG. 5, the first direction is the direction in which the optical element 264 is located with respect to the structuring means 220. The second direction is an output direction for making light incident on the photodetector 232. The second direction is the direction in which the optical element 265 is located with respect to the structuring means 220.

Specifically, the structuring means 220 includes a plurality of optical elements arranged two-dimensionally. The plurality of optical elements can emit incident light in either the first direction or the second direction. For example, the structuring means 220 is a digital mirror device and has a plurality of movable microscopic mirror surfaces as a plurality of optical elements.

The photodetector 231 is an example of a first light receiving element that receives light emitted from the structuring means 220 in the first direction. The photodetector 231 outputs a signal corresponding to the intensity of light of the first bright and dark pattern structured by the structuring means 220.

The photodetector 232 is an example of a second light receiving element that receives light emitted from the structuring means 220 in the second direction. The photodetector 232 outputs a signal corresponding to the intensity of the light of the second bright and dark pattern structured by the structuring means 220. For example,

photodetectors

231 and 232 are each one-pixel infrared detectors.

The control unit 240, like the control unit 40, performs overall control of the imaging device 201. Specifically, the control section 240 controls the light source 10, the structuring means 220, the

photodetectors

231 and 232, and the calculation section 250.

For example, the control unit 240 controls the switching timing of a plurality of bright and dark patterns by the structuring means 220. In the present embodiment, since it is possible to simultaneously obtain a signal of one light-dark pattern and a signal of its inverted light-dark pattern, the control unit 240 prevents the formation of an inverted pattern when controlling the structuring means 220. Make it. Further, the control unit 240 controls the output timing of the signal from each of the

photodetectors

231 and 232 so as to correspond to each of the plurality of bright and dark patterns. Further, the control unit 240 outputs information to the calculation unit 250 to enable association between brightness and darkness patterns and signals, and association with signals for each band.

The calculation unit 250 reconstructs a two-dimensional image of the object 90 by performing a cross-correlation calculation between the signals output from each of the

photodetectors

231 and 232 and the corresponding brightness/darkness pattern. The calculation unit 250 reconstructs a two-dimensional image for each band. As for a specific reconstruction method, ghost imaging or single pixel imaging can be used as in the first and second embodiments.

The optical elements 261 to 265 and the half mirror 266 are provided to adjust the optical path. Like the optical elements 61 to 64, each of the optical elements 261 to 265 controls the optical path by utilizing the difference in refractive index from the light propagation space.

The optical element 261 is, for example, a collimator that converts the light emitted from the light source 10 into parallel light. The optical element 262 is a projection lens that irradiates light emitted from the light source 10 and reflected by the half mirror 266 toward the object 90 . In this embodiment, optical element 262 is also an objective lens that condenses light (specifically, reflected light) from target object 90. That is, the optical element 262 is used for both the irradiation optical system and the objective optical system. The optical element 263 is a collimator that emits the light reflected from the object 90 and transmitted through the half mirror 266 as parallel light. The optical element 263 irradiates the structuring means 220 with parallel light. The optical element 264 is a condenser lens that condenses the light structured into the first bright and dark pattern by the structuring means 220 onto the photodetector 231 . The optical element 265 is a condenser lens that condenses the light structured into the second bright and dark pattern by the structuring means 220 onto the photodetector 232 .

The half mirror 266 is an optical element that separates the light irradiated onto the object 90 from the light (reflected light) from the object 90. Specifically, the half mirror 266 reflects the light from the light source 10 and transmits the reflected light from the object 90. By using the half mirror 266, the optical element 262 can be used both as an irradiation optical system and an objective optical system. Since the optical axis of the irradiation optical system and the optical axis of the objective optical system can be made the same, it is possible to improve the collection efficiency of reflected light from the object 90 and to suppress the intrusion of disturbance light.

Note that the configuration shown in FIG. 5 is only an example and can be modified as appropriate. For example, the irradiation optical system that irradiates light onto the target object 90 and the objective optical system that acquires the reflected light from the target object 90 may be realized by separate optical elements. In this case, the imaging device 201 does not need to include the half mirror 266.

FIG. 6 is a diagram showing the principle of the imaging device 201 according to this embodiment. In FIG. 6, for simplicity, a digital mirror device having five micromirror surfaces 221a to 221e is shown as the structuring means 220. Each of the five micromirror surfaces 221a to 221e corresponds to one pixel.

Each of the micromirror surfaces 221a to 221e reflects incident light in either direction A or direction B. In the example shown in FIG. 6, the

micromirror surfaces

221a, 221b, and 221e reflect the incident light in direction A. In the example shown in FIG. The micromirror surfaces 221c and 221d reflect the incident light in direction B. Note that the direction A is an example of the first direction, and the light reflected in the direction A is detected by the photodetector 231 in FIG. 5. Direction B is an example of a second direction, and light reflected in direction B is detected by photodetector 232 in FIG. 5.

As a result, the light/dark pattern of the light emitted in direction A becomes a pattern in which "bright", "bright", "dark", "dark", and "bright" are arranged in order from the top. The light/dark pattern of the light emitted in direction B is a pattern in which "dark", "dark", "bright", "bright", and "dark" are arranged in order from the top. That is, in direction A and direction B, mutually inverted light and dark patterns are obtained.

Thereby, signals corresponding to two bright and dark patterns can be obtained with one incident of light, that is, one measurement. The calculation unit 250 uses the signals of the two bright and dark patterns as detection signals to reconstruct a two-dimensional image. This makes it possible to shorten measurement time or reconstruct a high-quality two-dimensional image.

Alternatively, the calculation unit 250 may calculate the difference between the signals corresponding to the two bright and dark patterns, and use the difference signal to reconstruct the two-dimensional image. Noise can be suppressed by using the difference between the inverted light and dark patterns. This makes it possible to reconstruct a high-quality two-dimensional image.

(Embodiment 4)
Next, Embodiment 4 will be described.

Embodiment 4 differs from Embodiments 1 to 3 in that transmitted light from an object is detected. Below, the explanation will focus on the differences from Embodiments 1 to 3, and the explanation of common points will be omitted or simplified.

FIG. 7 is a diagram showing the configuration of an imaging device 301 according to this embodiment. As shown in FIG. 7, compared to the imaging device 2 shown in FIG. 1, the imaging device 301 includes

optical elements

362 and 363 instead of the optical elements 62 to 64 and the half mirror 65.

The optical element 362 is a projection lens that irradiates the object 90 with light structured by the structuring means 20. The target object 90 generates transmitted light by transmitting at least a portion of the irradiated light. The optical element 363 is an objective lens that condenses the light that has passed through the object 90 (that is, the transmitted light) out of the structured light emitted from the optical element 362. Note that the optical element 363 also functions as a lens that focuses light on the photodetector 30, but is not limited thereto. A dedicated lens for condensing light may be provided on the photodetector 30.

In this way, even when the transmitted light from the object 90 is detected, it is possible to reconstruct a two-dimensional image as in the first embodiment. Since the imaging device 301 according to this embodiment reconstructs a two-dimensional image for each band, a single-pixel detector can be used as the photodetector 30. That is, the sensor size can be reduced while suppressing a decrease in spatial resolution.

Note that, similarly to the second embodiment, the structuring means 20 may be arranged not on the light source 10 side but on the photodetector 30 side.

FIG. 8 is a diagram showing the configuration of an imaging device 302 according to this modification. As shown in FIG. 8, the imaging device 302 differs from the configuration of the imaging device 301 shown in FIG. 7 in the arrangement of the structuring means 20. The imaging device 302 also includes an optical element 364.

In this modification, the structuring means 20 is arranged between the optical element 363 and the optical element 364. That is, the structuring means 20 structures the light (specifically, transmitted light) emitted from the object 90 when irradiated with the light from the light source 10 into a plurality of two-dimensional bright and dark patterns. Optical element 364 focuses the light structured by structuring means 20 onto photodetector 30 .

In this way, even when the transmitted light from the object 90 is structured, it is possible to reconstruct a two-dimensional image as in the first embodiment. Since the imaging device 302 according to this modification reconstructs a two-dimensional image for each band, a single-pixel detector can be used as the photodetector 30. That is, the sensor size can be reduced while suppressing a decrease in spatial resolution.

Note that, similarly to the third embodiment, the imaging device 302 may include two

photodetectors

231 and 232 instead of the photodetector 30. That is, in the case of structuring the transmitted light from the object 90, the sensor size can be similarly reduced while suppressing a decrease in spatial resolution.

(Other embodiments)
Although the imaging device according to one or more aspects has been described above based on the embodiments, the present disclosure is not limited to these embodiments. Unless departing from the gist of the present disclosure, various modifications that can be thought of by those skilled in the art to this embodiment, and configurations constructed by combining components of different embodiments are also included within the scope of the present disclosure. It will be done.

For example, the light emitted by the light source may be light with a longer wavelength than mid-infrared rays. Specifically, the light emitted from the light source may be far infrared rays with a wavelength band of 10 μm or more and 30 μm or less, or may be terahertz waves with a wavelength band of 30 μm or more and 3 mm or less.

Alternatively, the light emitted by the light source may be light with a shorter wavelength than visible light. Specifically, the light emitted by the light source may be ultraviolet light having a wavelength band of 10 nm or more and 400 nm or less, or may be X-rays or electron beams.

Furthermore, for example, the light emitted by the light source may be excitation light that excites the object 90. In this case, the object 90 is excited and emits fluorescence when irradiated with light. The photodetector may detect fluorescence from the object 90 as the light emitted from the object 90.

Furthermore, for example, when a broadband light source and a filter are used as the light source 10, the filter may be placed on the photodetector side. In other words, the light source 10 may emit broad light including each of the plurality of different bands, as the light of the plurality of different bands. In this case, a filter corresponding to a band corresponding to the component to be measured is placed on the light incident side of the photodetector.

Additionally, the photodetector may be an image sensor having multiple pixels. The number of pixels of the image sensor may be smaller than the number of micro areas of the structuring means. By using the detection results of each of the plurality of pixels, a two-dimensional image with better image quality can be reconstructed. Alternatively, light for each band may be incident on each of the plurality of pixels. Thereby, light in multiple bands can be detected simultaneously.

Additionally, the photodetector may include a wavelength conversion member. The wavelength conversion member is, for example, an up-conversion type wavelength conversion member, and converts light in the mid-infrared band to visible light or near-infrared light. Thereby, an inexpensive visible light sensor or near-infrared light sensor can be used as the photodetector.

Additionally, various changes, substitutions, additions, omissions, etc. can be made to each of the above embodiments within the scope of the claims or their equivalents.

The present disclosure can be used in various analysis devices and inspection devices, such as component analysis of a target object or determination of foreign matter contamination.

1, 2, 101, 201, 301, 302 Imaging device 10 Light source 11

Light source section

20, 220 Structuring means 30, 231, 232

Photodetector

40, 240

Control section

50, 250

Arithmetic section

61, 62, 63, 64, 261, 262, 263, 264, 265, 362, 363, 364

Optical element

65, 266 Half mirror 90

Object

221a, 221b, 221c, 221d, 221e Microscopic mirror surface

Claims

a light source unit that structures and emits light into a plurality of two-dimensional bright and dark patterns;
a photodetector that detects light emitted from the object when the object is irradiated with light from the light source;
a calculation unit that reconstructs a two-dimensional image of the object by performing a cross-correlation calculation between the signal output from the photodetector and the corresponding brightness pattern;
The light source unit emits light in a plurality of different bands,
The calculation unit reconstructs the two-dimensional image for each band,
Imaging device.
The light source section is
a light source and
structuring means for structuring the light from the light source into the plurality of two-dimensional bright and dark patterns;
The imaging device according to claim 1.
a light source unit that emits light;
structuring means for structuring light emitted from the object into a plurality of two-dimensional bright and dark patterns when the object is irradiated with light from the light source;
a photodetector that detects the light structured by the structuring means;
a calculation unit that reconstructs a two-dimensional image of the object by performing a cross-correlation calculation between the signal output from the photodetector and the corresponding brightness pattern;
The light source unit emits light in a plurality of different bands,
The calculation unit reconstructs the two-dimensional image for each band,
Imaging device.
The structuring means includes a plurality of optical elements arranged two-dimensionally,
The plurality of optical elements are capable of emitting incident light in either a first direction or a second direction different from the first direction,
The photodetector is
a first light receiving element that receives light emitted from the structuring means in the first direction;
a second light receiving element that receives light emitted from the structuring means in the second direction;
The imaging device according to claim 2.
the structuring means is a digital mirror device, an active matrix liquid crystal device or a spatial light modulator;
The imaging device according to any one of claims 2 to 4.
The plurality of bands are included in a wavelength band of 2 μm or more and 10 μm or less,
The imaging device according to any one of claims 1 to 5.
The calculation unit further estimates the chemical composition of the object based on a signal intensity ratio of the two two-dimensional images for each of at least two bands.
An imaging device according to any one of claims 1 to 6.
The light emitted from the target object is reflected light generated when the target object reflects at least a part of the light from the light source unit.
An imaging device according to any one of claims 1 to 7.
The light emitted from the target object is transmitted light generated when the target object transmits at least a part of the light from the light source unit.
An imaging device according to any one of claims 1 to 7.