CN212694048U

CN212694048U - Image forming apparatus and image forming system

Info

Publication number: CN212694048U
Application number: CN202021746397.6U
Authority: CN
Inventors: 不公告发明人
Original assignee: DeepRoute AI Ltd
Current assignee: DeepRoute AI Ltd
Priority date: 2020-08-19
Filing date: 2020-08-19
Publication date: 2021-03-12
Anticipated expiration: 2030-08-19

Abstract

The present application relates to an imaging apparatus and an imaging system, wherein: the light source emits illumination light; the spatial light modulator carries out light field modulation on the illumination light emitted by the light source according to the received modulation signal; the emission lens optically projects the light modulated by the spatial light modulator onto a target object; the receiving lens receives light reflected by a target object and converges the light on photosensitive surfaces of the first detector and the second detector; the polarization light splitting device receives light reflected by a target object and divides the light reflected by the target object into two beams of light with different propagation directions and mutually vertical polarization; the first detector and the second detector correspondingly receive two beams of light of the polarization beam splitter one by one and obtain a first electric signal and a second electric signal after photoelectric conversion; the controller outputs the modulation signal and obtains an image of the target object according to the first electrical signal, the second electrical signal and the modulation signal. The imaging device has the advantages of good imaging effect and low cost by taking diffuse reflection objects and specular reflection objects into consideration.

Description

Image forming apparatus and image forming system

Technical Field

The utility model relates to an associated imaging technology field especially relates to an imaging device and imaging system.

Background

The statements herein merely provide background information related to the present application and may not necessarily constitute prior art.

The ghost imaging method is an indirect imaging mode, the light field distribution irradiated on a target object is obtained, and the image of the object can be obtained through a correlation algorithm or a compressed sensing method. In the scheme of realizing active illumination and firstly modulated ghost imaging, light emitted by a light source is modulated into known and controllable modulated light through a spatial light modulator and is projected on a target object through an emission lens; the receiving lens collects and modulates the light reflected by the object after the light is irradiated on the object, and the light is detected by the detector and converted into an electric signal; and the computing system computes the collected signals and the modulation signals sent by the control system to obtain the image of the target object. Compared with the traditional imaging mode, ghost imaging has the advantages of high sensitivity, low cost and the like, and is applied to the fields of remote sensing, laser radar, video monitoring and the like.

When imaging is carried out, the target object may be a diffuse reflection object, and the return light signal is weak; it may also be a specular object, with a strong return light signal. If a detector with high sensitivity is adopted, when the target object is a mirror reflection object, the light received by the detector is strong, and the detector can be saturated or even damaged; if a detector with low sensitivity is adopted, when the target object is a diffuse reflection object, the light received by the detector is weak, and a clear image cannot be recovered due to the insufficient signal-to-noise ratio; if a detector with a detection range capable of simultaneously considering both large signals and small signals is adopted, the cost is high.

SUMMERY OF THE UTILITY MODEL

Therefore, it is necessary to provide an imaging device and an imaging system for solving the problem that a detector cannot measure both large signals and small signals, and ensuring the imaging effect, aiming at the problem that the reflected light intensities of a diffuse reflection object and a specular reflection object are different.

An embodiment of the utility model provides an imaging device, include:

a light source for emitting illumination light;

the spatial light modulator is used for carrying out light field modulation on the illumination light emitted by the light source according to the received modulation signal;

an emission lens for optically projecting the light modulated by the spatial light modulator onto a target object;

the receiving lens is used for receiving the light reflected by the target object and converging the light on the photosensitive surfaces of the first detector and the second detector;

the polarization light splitting device is used for receiving light reflected by a target object and splitting the light reflected by the target object into two beams of light with different propagation directions and mutually vertical polarization;

the first detector and the second detector correspondingly receive the two beams of light of the polarization light splitting device one by one, and a first electric signal and a second electric signal are obtained after photoelectric conversion;

and the controller is respectively electrically connected with the spatial light modulator, the first detector and the second detector, is used for outputting the modulation signal, and is used for obtaining the image of the target object according to the first electric signal, the second electric signal and the modulation signal.

In one embodiment, the target object includes: specular reflective objects and/or diffuse reflective objects.

In one embodiment, the receiving lens is disposed between the target object and the polarization splitting device.

In one embodiment, the polarization beam splitter is disposed between the target object and the receiving lens;

the receiving lens includes:

the first lens group is used for receiving and projecting a beam of light split by the polarization light splitting device to the first detector;

and the second lens group is used for receiving and projecting the other beam of light split by the polarization beam splitting device to the second detector.

In one embodiment, the polarization beam splitter is a polarization beam splitter prism or a Glan-Taylor prism.

In one embodiment, the illumination light is completely unpolarized, s-polarized, or p-polarized.

In one embodiment, the first detector is a single pixel detector; and/or the second detector is a single-pixel detector.

In one embodiment, the spatial light modulator is a digital micromirror device.

In one embodiment, the controller comprises:

the modulation module is electrically connected with the spatial light modulator and is used for outputting the modulation signal;

and the computing module is respectively electrically connected with the modulation module and the detector and is used for obtaining the image of the target object according to the first electric signal, the second electric signal and the modulation signal.

An imaging system includes the above imaging apparatus.

According to the difference between the polarization characteristics of the reflected light of the diffuse reflection object and the polarization characteristics of the reflected light of the specular reflection object, the reflected light of the diffuse reflection object has the polarization characteristics of the completely unpolarized light, and the specular reflected light is the linearly polarized light or the partially polarized light, the imaging device provided by the embodiment of the application emits the illumination light (the completely unpolarized light or the s-polarized light or the p-polarized light) to the spatial light modulator, and the illumination light is modulated by the spatial light modulator to form a controllable and known light signal, the light signal is projected on a target object through an emission lens, the target object can comprise the specular reflection object and the diffuse reflection object, and the reflected light of the object is separated according to polarization by using the polarization difference between the polarization splitting device and the two objects, for example, the reflected light of the object is split by using the polarization splitting prism, and the intensity of the transmitted light and the reflected light has the difference, the first detector and the second detector with different sensitivities detect the signal respectively, a first electric signal and a second electric signal are correspondingly generated, and the controller calculates according to the received first electric signal and the second electric signal and the modulation signal sent to the spatial light modulator, so that a complete image of the target object can be obtained. The imaging device that this application example provided can compromise diffuse reflection object and specular reflection object, and the formation of image is effectual, and overall cost is low.

Drawings

FIG. 1 is a schematic configuration diagram of an imaging apparatus and an imaging system in one embodiment;

fig. 2 is a schematic structural view of an imaging apparatus and an imaging system in another embodiment;

fig. 3 is a schematic structural view of an imaging apparatus and an imaging system in still another embodiment.

Detailed Description

In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element and be integral therewith, or intervening elements may also be present. The terms "mounted," "one end," "the other end," and the like are used herein for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

An embodiment of the present invention provides an image forming apparatus, as shown in fig. 1, fig. 2, and fig. 3, including: a light source 80 for emitting illumination light; a spatial light modulator 10 for performing light field modulation on the illumination light emitted from the light source according to the received modulation signal; an emission lens 20 for optically projecting the light modulated by the spatial light modulator onto a target object; a receiving lens 50, configured to receive light reflected by the target object, and converge the light onto photosensitive surfaces of the first detector 30 and the second detector 40; the polarization beam splitter 60 is configured to receive light reflected by a target object, and split the light reflected by the target object into two beams of light with different propagation directions and mutually perpendicular polarizations; the first detector 30 and the second detector 40 correspondingly receive the two beams of light from the polarization beam splitter 60 one by one, and perform photoelectric conversion to obtain a first electrical signal and a second electrical signal, and the controller 70 is electrically connected to the spatial light modulator 10, the first detector 30, and the second detector 40, respectively, and is configured to output the modulation signal and obtain an image of the target object according to the first electrical signal, the second electrical signal, and the modulation signal.

The light source 80 is an object that can emit light by itself and is emitting light, and may further include a beam expanding lens. The polarization characteristic of the emitted light may be completely unpolarized light, p-polarized light or s-polarized light. The emission lens 20 may be a single lens, a cemented lens, or a lens group including a plurality of lenses. The receiving lens 50 may be a single lens, a cemented lens, or a lens group including a plurality of lenses. The specular reflection object is an object with reflected light concentrated in a specific direction, and the light received by the detector is strong. The spatial light modulator 10 is composed of a plurality of spatial light modulation units, each of which can independently modulate a parameter of the light field, for example, modulate the amplitude of the light field, modulate the phase through the refractive index, modulate the polarization state through the rotation of the polarization plane, or realize the conversion of incoherent-coherent light, so as to write a certain information into the light wave, thereby achieving the purpose of modulating the light wave. The spatial light modulator 10 may be a digital micromirror device, an Acousto-optic deflection crystal (AOD), a liquid crystal spatial light modulator 10, or a metamaterial. When the spatial light modulator 10 is a digital micromirror device, the spatial light modulator 10 can achieve light modulation by driving micromirrors thereon on or off. When the spatial light modulator 10 is an acousto-optic deflection crystal, the refractive index can be changed along with an externally applied signal by changing the applied signal, thereby realizing light modulation. When the spatial light modulator 10 is a metamaterial (which may be a light-operated metamaterial), the nanostructure of the metamaterial can scatter light in a specific manner, and light modulation can be achieved by adjusting the absorption characteristics of the surface of the metamaterial. The modulation signal is used for controlling the change of the spatial refractive index of the spatial light modulator 10, the modulation signal may be a pseudo-random signal, and the like, and the implementation of the imaging by the controller 70 according to the first electrical signal, the second electrical signal and the modulation signal may be implemented according to an existing associated imaging algorithm or a compressed sensing algorithm, and the like. The polarization splitting device 60 is a device capable of splitting light having different polarization characteristics among the received light, and may be a polarization splitting prism, a glan-taylor prism, or the like. The first and second detectors (30, 40) are photodetectors capable of detecting optical signals and converting the optical signals into electrical signals, and can output current, voltage or digital signals of corresponding intensities according to incident light intensities. According to the wavelength of the optical signal to be processed, the detector can take silicon, germanium, indium gallium arsenic, cadmium selenide and the like as detection materials. Specifically, the detector may be, but is not limited to, a single-pixel detector, and may also be a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), an MPPC (multi-pixel photo multiplier), or the like, and it should be noted that the examples herein do not limit the actual protection scope of the present application.

Specifically, an imaging device (a first-modulation polarization beam splitting imaging device) is shown in fig. 1 and 2. The illumination light (completely unpolarized light, s-polarized light or p-polarized light) emitted by the light source is modulated by the spatial light modulator 10 to form known and controllable modulated light, the modulated light is projected on a target by the emission lens 20, the reflected light of objects with different reflectivities in the target object passes through the receiving lens 50 and then is projected on the polarization beam splitter 60, the polarization beam splitter 60 separates the reflected light of the two objects by utilizing the polarization characteristic difference between the specular reflection object and the diffuse reflection object to form two light beams, and then the two light beams are respectively detected by the first detector 30 and the second detector 40 and correspondingly generate a first electric signal and a second electric signal, by adopting the mode, the problem that when the reflected light of the specular reflection object and the diffuse reflection object is detected by one detector at the same time, the reflected light signal of the diffuse reflection object cannot be recognized by the detector due to the fact that the reflected light signal cannot obtain enough signal, therefore, the detection effect of the objects with different reflectivity is ensured, and then the controller 70 can calculate (can adopt correlation operation or compressed sensing algorithm and the like) according to the first electric signal, the second electric signal and the modulation signal to respectively obtain the complete images of the target objects, so that the imaging effect is good.

The imaging device provided by the embodiment of the application utilizes the polarization difference of different types of reflected light of an object, utilizes the polarization beam splitter 60 to separate the reflected light of the object according to polarization to obtain two beams of light with different intensities, and the two beams of light are respectively detected by the first detector 30 and the second detector 40 with different sensitivities, so that the requirements on the detectors are reduced, the first electric signal and the second electric signal are correspondingly generated, and the complete image of the target object can be obtained by utilizing the computing capability of the controller 70.

In one embodiment, the target object comprises a specular reflective object and/or a diffuse reflective object.

The diffuse reflection object is an object that reflects light reflected by the light source in all directions after the object is irradiated by the light source. The specular reflection object refers to an object with a smooth surface, such as a water surface or glass, and when a parallel incident light ray hits the reflection surface, the parallel incident light ray still reflects in one direction. When the illumination light source is completely unpolarized light, the reflected light from the diffuse reflection object is also completely unpolarized light, and the reflected light from the specular reflection object is partially polarized light (the s component is large and the p component is small). When the illumination light source is s-polarized light, the reflected light from the diffuse reflection object also has polarization characteristics of completely unpolarized light, while the reflected light from the specular reflection object is linearly polarized light (s-polarized light) or partially polarized light (s-polarized light is abundant and p-polarized light is scarce). When the illumination light source is p-polarized light, the reflected light from the diffuse reflection object also has polarization characteristics of completely unpolarized light, while the reflected light from the specular reflection object is linearly polarized light (p-polarized light) or partially polarized light (p-polarized light is abundant and s-polarized light is scarce). According to the polarization difference, a polarization light splitting device is added before detection, p-polarized light and s-polarized light of a light beam are separated, so that the light is divided into a strong light part and a weak light part, the two detectors with different sensitivities are used for detection respectively, the requirements on the detectors are reduced, the cost is reduced, complete imaging can be realized, and the imaging effect is ensured.

In one embodiment, the receiving lens 50 is disposed between the target object and the polarization splitting device 60. The polarization beam splitter 60 is disposed between the receiving lens 50 and the first detector 30 and the second detector 40, so that the first detector 30 and the second detector 40 respectively receive the two beams of light separated by the polarization beam splitter, and different detectors are used for detection, thereby ensuring the imaging effect and the imaging quality of the target object.

In one embodiment, the polarization beam splitter is disposed between the target object and the receiving lens 50; the receiving lens 50 includes: the first lens group 51, the first lens group 51 is configured to receive and project a beam of light obtained by separating the polarization beam splitter to the first detector 30; and the second lens group 52 is used for receiving and projecting another beam of light obtained by splitting the polarization beam splitter to the second detector 40. The light reflected by the target object can be separated, and then the first lens group 51 and the second lens group 52 correspondingly receive and project two beams of light with vertical polarization directions to the first detector 30 and the second detector 40, respectively.

In one embodiment, the polarization beam splitter device 60 is a Glan Taylor prism or a polarization beam splitter prism. The Glan Taylor prism is a birefringent polarizing beam splitter 60 made of natural calcite crystal, the main component is CaCO₃The rhombohedral crystal of (1). Compared with other polarization beam splitter 60 light (such as a polarizing plate),the transmittance and the polarization purity are higher. The polarization beam splitter prism is a device capable of splitting incident unpolarized light into two vertical linearly polarized light beams. Wherein p-polarized light passes completely, and s-polarized light is reflected at an angle of 45 degrees, with the exit direction making an angle of 90 degrees with respect to the p-polarized light. The polarization beam splitter prism can be formed by gluing a pair of high-precision right-angle prisms, and the oblique side of one prism is coated with a polarization beam splitting dielectric film. When the polarization beam splitter 60 is a polarization beam splitter prism and the polarization beam splitter 60 is disposed between the receiving lens 50 and the first detector 30, if the illumination is performed by using the completely unpolarized light, the reflected light of the diffuse reflection object is still the completely unpolarized light, and the reflected light of the specular reflection object is the partially polarized light; when s-linear polarized light or p-linear polarized light is adopted for illumination, the reflected light of the diffuse reflection object is still completely unpolarized light, and the reflected light of the specular reflection object is linearly polarized light or partially polarized light. According to the polarization characteristic difference of the first object reflected light and the second object reflected light, the light to be measured formed by the modulation of the spatial light modulator 10 is separated into two beams of light after passing through the polarization beam splitter prism, the polarization directions of the reflected light and the transmitted light of the polarization beam splitter prism are different, the light intensity is different, the first detector and the second detector with different sensitivities can be used for detecting to obtain a first electric signal and a second electric signal, the controller 70 further obtains a complete image of the target object according to the first electric signal, the second electric signal and the modulation signal, and the imaging effect is good. Other types of devices for analyzing the polarization may be used in addition to those listed herein, and other alternatives that may be contemplated by one skilled in the art based on the embodiments described herein are within the scope of the present application.

In one embodiment, the first detector 30 is a single pixel detector; and/or the second detector 40 is a single pixel detector. In one embodiment, the spatial light modulator 10 is a digital micromirror device.

A single pixel detector is a particle track detector with silicon as the detection material, a semiconductor detector with a single pixel to output data when a particle passes through the single pixel, for example, to convert received light modulated by a digital micromirror device into an electrical signal. The single-pixel detector is a general name of detectors which can only detect light intensity and cannot distinguish space information. Photodiodes, photomultiplier tubes, avalanche photodiodes, and the like are commonly used.

A digital micro-mirror device (DMD) is a spatial light modulator 10 consisting of an array of aluminum micro-mirrors of a size of a few microns, each having only two states, on and off (i.e., +12 ° and-12 ° rotation about its diagonal), which allows a specific amplitude modulation of the light. In performing the light modulation, the micromirrors in the DMD are turned in a row-driven fashion, often by outputting a random encoding matrix (modulation signal) to the DMD.

When a single-pixel detector is adopted, the single-pixel detector is matched with a digital micro-mirror device, when linearly polarized light emitted by a light source is modulated by a DMD (digital micromirror device), controllable and known light is formed and projected on a first object and a second object through an emitting lens 20, a receiving lens 50 receives a target signal, and a polarization light splitting device 60 splits the target signal received by the receiving lens 50 to form two beams of light which are respectively detected by a first detector 30 and a second detector 40. During shooting, the light and shade matrix reflected by each lens on the DMD is rapidly changed in a pseudo-random code mode, and the detector 20 collects an optical signal and converts the optical signal into an electric signal once every time the change is made. And finally, the image of the object is obtained by comprehensively calculating the electric signal and the pseudo-random code each time, and at the moment, the imaging device provided by the embodiment of the application is firstly modulated ghost imaging.

To better explain the working principle of the imaging device provided in the embodiment of the present application, an example is given in which the imaging device is a single-pixel camera, the first type of object is a diffuse reflection object, and the second type of object is a specular reflection object, and a single-pixel camera that simultaneously detects the diffuse reflection object and the specular reflection object by using the polarization difference of reflected light is shown in fig. 1 and 2. The illumination light (completely unpolarized light, s-polarized light or p-polarized light) emitted by the light source is modulated by the spatial light modulator 10 to form controllable known modulated light, the modulated light is projected on a target object through the emission lens 20, the modulated light illuminates a diffuse reflection object and a specular reflection object, the reflected light (target signal) of the two objects is projected to the polarization splitting prism through the receiving lens 50, the transmitted light and the reflected light are respectively detected by the first detector 30 and the second detector 40 and are correspondingly converted into a first electric signal and a second electric signal, and after the detection, the controller 70 calculates (correlation operation or compression perception algorithm, etc.) the collected first electric signal and the collected second electric signal and the modulation signal emitted by the controller 70 to obtain an image of the target object.

In one embodiment, the controller 70 includes: a modulation module 71, wherein the modulation module 71 is electrically connected to the spatial light modulator 10, and is configured to output the modulation signal; a calculating module 72, wherein the calculating module 72 is electrically connected to the modulating module 71 and the detector, respectively, for obtaining the image of the first object according to the first electrical signal and the modulating signal, and for obtaining the image of the second object according to the second electrical signal and the modulating signal.

The modulation module 71 mainly refers to a device capable of generating a modulation signal, and may be, for example, a pulse generator, a pseudo-random signal generator, or the like. The calculating module 72 is a device capable of calculating an image of the first type object according to the modulation signal and the electrical signal, and may be a device composed of a plurality of chip devices. Specifically, the modulation module 71 outputs a modulation signal to the driving module, and the driving module drives the micromirror to mechanically flip. The driving module can drive line by line to perform light modulation, an optical signal formed after modulation is projected to a first object and a second object through the transmitting lens 20, the receiving lens 50 receives a target signal, the target signal is split through the polarization splitting device 60 to form two light beams, the two light beams are respectively detected by the first detector 30 and the second detector 40 and are correspondingly converted into a first electric signal and a second electric signal to be output to the calculating module 72, and finally, the calculating module 72 analyzes and processes the modulation signal, the first electric signal and the second electric signal according to a compression sensing algorithm or a correlation algorithm and the like, and finally an image of the target object is obtained.

In one embodiment, the digital micromirror device comprises: the driving module and the micromirrors; the driving module is electrically connected to the controller 70, and the driving module is configured to drive the on/off state of each micromirror according to the modulation signal. The driving implementation process in which the driving module drives each micromirror to turn over line by line can be described with reference to the product of DMD and the working principle in the instruction manual of texas instruments.

The imaging device provided by the embodiment of the application utilizes the polarization difference of the reflected light of different types of objects, utilizes the polarization beam splitter 60 to separate the reflected light of the objects according to polarization to obtain two beams of light with different intensities, and the two beams of light are respectively detected by the first detector 30 and the second detector 40 with different sensitivities, so that the requirements on the detectors are reduced, the first electric signal and the second electric signal are correspondingly generated, and the complete image of the target object can be obtained by utilizing the computing capability of the controller 70.

An imaging system, comprising: and the imaging device.

The imaging system provided in the embodiment of the present application can achieve the beneficial effects of the imaging device, and the working implementation process of the imaging system can refer to the description in the above embodiment of the imaging device 2, which is not described herein again.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. An image forming apparatus, comprising:

a light source for emitting illumination light;

2. The imaging apparatus of claim 1, wherein the target object comprises: specular reflective objects and/or diffuse reflective objects.

3. The imaging apparatus according to claim 1 or 2, wherein the receiving lens is disposed between the target object and the polarization splitting device.

4. The imaging apparatus according to claim 1 or 2, wherein the polarization splitting device is disposed between the target object and the receiving lens;

the receiving lens includes:

the first lens group is used for receiving and projecting a beam of light obtained by the separation of the polarization light splitting device to the first detector;

and the second lens group is used for receiving and projecting the other beam of light obtained after the polarization beam splitter is separated to the second detector.

5. The imaging apparatus according to claim 1 or 2, wherein the polarization splitting device is a polarization splitting prism or a glantylor prism.

6. The imaging apparatus of claim 1 or 2, wherein the illumination light is completely unpolarized light, s-polarized light, or p-polarized light.

7. The imaging apparatus of claim 1 or 2, wherein the first detector is a single pixel detector; and/or the second detector is a single-pixel detector.

8. An imaging device according to claim 1 or 2, wherein the spatial light modulator is a digital micromirror device.

9. The imaging apparatus according to claim 1 or 2, wherein the controller includes:

10. An imaging system comprising the imaging apparatus of any one of claims 1 to 9.