Multispectral parallel single-pixel imaging system and imaging method

Abstract

The invention discloses a multispectral parallel single-pixel computing imaging system and method, and in one embodiment, the multispectral parallel single-pixel imaging system can comprise one or more imaging lenses, at least two filtering devices, at least two single-pixel detectors, a coding code disc and a code disc driver. According to the imaging system disclosed by the invention, multispectral parallel single-pixel imaging is realized by utilizing the space on the coded disc, and multispectral imaging with high imaging speed and wide working wave band can be realized.

Description

Technical Field

[0001] The present application relates to the field of imaging technology, and in particular to a multi-spectral parallel single-pixel imaging system and an imaging method. Background Art

[0002] Single pixel imaging (SPI) technology is a new type of imaging technology. Its hallmark feature is that it only uses a single-pixel detector without spatial resolution to record image information. Its core is to use structured light or coding to modulate the scene, and then use a single-pixel detector to collect one-dimensional signals. The detection signal and the corresponding coding sequence are reconstructed to obtain the two-dimensional information of the object.

[0003] The single-pixel imaging system mainly consists of three parts: light source, sample and detector. The most important factors affecting single-pixel imaging are the selection of modulation strategy and reconstruction method. Using a spatial light modulator to encode the scene can simplify the difficulty of obtaining two-dimensional information and achieve image acquisition through only a single-pixel detector. In single-pixel imaging systems, liquid crystal spatial light modulators, digital micromirror devices, etc. are generally used as optical modulators, but they have the defects of slow imaging speed and few modulation bands.

[0004] Multispectral imaging technology is different from traditional single wide-band imaging technology. The information obtained not only includes two-dimensional spatial information, but also spectral radiation information distributed with wavelength. Multispectral imaging technology can simultaneously obtain information on the spatial dimension and spectral dimension of an object. Since its information has spatial and spectral resolution capabilities, it can greatly improve the accuracy of target detection.

[0005] The multispectral imaging technology is integrated with the single-pixel imaging technology to obtain the multispectral single-pixel imaging technology, which can effectively restore the multispectral image of the target scene. The existing multispectral single-pixel imaging technologies are mainly divided into the following categories: (1) Directly using the spectrometer as a detector for detection, which can achieve high spectral resolution imaging, but also makes the entire system expensive and bulky; (2) Using mechanical structures such as color wheels and special encoding wheels to encode the spectrum to restore the spectral cube of the object to be measured from the one-dimensional intensity information. This type of system has the disadvantages that the spectral encoding speed is limited by the mechanical structure and the stability is poor; (3) Based on Fourier single-pixel imaging technology, color coding patterns are used to simultaneously encode spatial and color information, but there are disadvantages such as limited imaging spectrum, slow projection speed of color coding patterns, and low imaging efficiency. It can be seen that the existing technology has the disadvantages of cumbersome multispectral experimental data acquisition method, multiple experiments are required for data acquisition, and there are few spectral bands that can be collected in parallel.

[0006] Therefore, using a single-pixel imaging system to achieve multispectral imaging with fast data acquisition speed and rich spectral bands is an urgent problem to be solved in this field. Summary of the invention

[0007] In order to solve the above technical problems, the present application is proposed. The embodiments of the present application provide a multi-spectral single-pixel imaging system and imaging method. The imaging system and method can significantly increase the spectral range of multi-spectral single-pixel imaging, simplify the data acquisition method, and improve the data acquisition speed.

[0008] According to one aspect of the present application, a multi-spectral parallel single-pixel imaging system is provided, comprising: one or more imaging lenses, at least two filter devices, at least two detectors, an encoding code disk and a code disk driver; wherein the number of the filter devices and the detectors is the same; the imaging lens is used to image the object to be measured onto the encoding position of the encoding code disk; the filter device is used to filter the light passing through the imaging lens; the detector is a single-pixel detector, used to receive the light signal passing through the corresponding filter device; the code disk driver is configured to drive the encoding code disk to rotate at a uniform speed, so as to achieve relative movement between the object to be measured and the mask on the encoding code disk.

[0009] In some embodiments, the imaging system further includes a reconstruction unit, wherein the reconstruction unit is configured to receive data collected by the at least two detectors, and to process the data to reconstruct images of the object to be detected in different spectral bands.

[0010] In some embodiments, the filtering devices are optical filters, each of which selectively transmits a different wavelength spectrum.

[0011] In some embodiments, the filter element is disposed between the encoder disk and the detector.

[0012] In some embodiments, the filter device is combined with the detector.

[0013] In some embodiments, the filter element is disposed between the imaging lens and the encoder disk.

[0014] In some embodiments, the filter device is combined with the imaging lens.

[0015] In some embodiments, the number of the filter devices and detectors is consistent, and the number of the above devices is at least 2, preferably more than 3.

[0016] In some embodiments, a cyclic S matrix is ​​engraved on the mask of the encoding code disk.

[0017] According to another aspect of the present application, a multi-spectral parallel single-pixel imaging method is provided, comprising: imaging an object to be measured onto different positions on a mask of an encoding code disk through one or more imaging lenses; driving the encoding code disk to rotate at a uniform speed so that a relative displacement occurs between the mask on the encoding code disk and the object to be measured until all encoding areas of the encoding code disk are measured relative to the object to be measured; selectively transmitting light of different wavelength bands through at least two filter devices for light signals passing through the imaging lens or the mask and receiving them respectively by corresponding single-pixel detectors; and processing the data collected by the detector to reconstruct a multi-spectral image of the object to be measured.

[0018] Based on some embodiments, the imaging system and method of the present application utilize the spatial distribution of the encoding code disk and its characteristics that imaging can be performed in the area covered by the rotating code. Multi-spectral parallel single-pixel imaging is achieved by adopting multiple filter devices and single-pixel detectors for parallel imaging. This can increase the imaging spectral range while significantly reducing data acquisition time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0020] Figure 1 A schematic diagram showing the composition of a multi-spectral parallel single-pixel imaging system in an embodiment of the present application is shown;

[0021] Figure 2 A schematic diagram showing the composition of a multi-spectral parallel single-pixel imaging system in an embodiment of the present application is shown;

[0022] Figure 3 A schematic diagram showing the positional relationship between an imaging lens and an encoding code disk according to an embodiment of the present application;

[0023] Figure 4 A three-dimensional schematic diagram showing the optical path channel and the position of the code disk according to an embodiment of the present application;

[0024] Figure 5 A parallel single-pixel imaging system of N spectral channels according to an embodiment of the present application is shown;

[0025] Figure 6 A parallel single-pixel imaging system of N spectral channels according to an embodiment of the present application is shown;

[0026] Figure 7A flow chart of a multi-spectral parallel single-pixel imaging method according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0027] The following will describe in detail the example embodiments according to the present application with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals generally represent the same components. It should be understood that the dimensions and sizes of the components shown in the accompanying drawings are not necessarily drawn to true scale, and they may be different from the embodiments shown here for implementation. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application, and the present application is not limited to the example embodiments described here.

[0028] Figure 1 FIG. 2 shows a schematic diagram of the overall structure of a multi-spectral parallel single-pixel imaging system according to an embodiment of the present application. Figure 1 As shown, the imaging system mainly includes the following parts: an imaging lens 110, an encoding disc 120, a disc motor 122, multiple (at least two) filter devices 132-134, and multiple (at least two) detectors 142-144. Among them, the imaging lens 110 may include one or more lenses (one is shown in the figure), which is used to image the target object to be measured to the encoding position of the encoding disc 120 in multi-channel; the number of filter devices and detectors is the same (two are shown in the figure), and the two correspond one to one, and are used to filter and detect the imaging of multiple channels. Specifically, the filter devices 132-134 are used to filter the light passing through the imaging lens and the encoding disc, and the detectors 142-144 are single-pixel detectors, which are used to receive the light signal passing through the corresponding filter device. The detector can convert the optical signal into an electrical signal, and the multi-channel signals collected by the detector can be processed by the reconstruction unit 150 to obtain a multi-spectral image.

[0029] In one example, the encoding code disk 120 is in the shape of a disk, on which a coding area is arranged. For example, a cyclic S-matrices (the formed pattern is also called a mask) is formed in the coding area by metal evaporation, ultraviolet photolithography, etc., and its function is to change the transmission intensity of the incident light beam, thereby spatially encoding the incident light.

[0030] According to the embodiment of the present application, the encoding code disk 120 can be driven by the code disk motor 122 to rotate at a constant speed, so that the image of the target object to be measured and the mask on the encoding code disk 120 can move relative to each other, thereby achieving the effect of modulating the image of the object. For example, when the encoding code disk is rotated one circle, the image of the object will sequentially scan the cyclic S matrix of the mask, thereby achieving a complete sampling.

[0031] At the same time, the embodiment of the present application filters different spectral information through multiple different filter devices. For example, the filter device uses a filter, and each filter can be configured to selectively transmit spectra of different wavelengths. Furthermore, the detector associated with each filter can receive spectral information of different wavelengths in parallel, and a multi-spectral single-pixel image can be reconstructed based on the multi-channel spectral information. The embodiment of the present application realizes multi-spectral parallel single-pixel imaging by using multiple filter devices and detectors for parallel imaging, which can increase the imaging spectral range and significantly reduce data acquisition time.

[0032] In one example, if Figure 1 As shown, the imaging lens 110 can use one lens. In this case, in order to facilitate the imaging of multiple channels, the imaging lens 110 needs to be configured to image the target object in different areas of the encoding code disk 120. Preferably, the imaging area of ​​the imaging lens 110 is configured to be larger so that it can cover two or more optical path channels, and filter devices are respectively arranged after the corresponding encoding areas, so that multi-spectral parallel imaging can be achieved.

[0033] Figure 2 A schematic diagram showing the composition of a multi-spectral parallel single-pixel imaging system according to another embodiment of the present application is shown as follows: Figure 2 As shown, the imaging system includes a plurality of imaging lenses 212-216, an encoding code disk 220, a code disk motor 222, a plurality of filter devices 232-236, a plurality of detectors 242-246, and a reconstruction unit 250. It can be seen that Figure 2 The system shown is Figure 1 The main difference lies in the number of imaging lenses. In this embodiment, the number of imaging lenses, filter devices, and detectors is consistent and one-to-one corresponding. The target object is imaged on the encoding code disk in multi-channel through multiple imaging lenses 212-216, and each channel obtains spectral information of different wavelengths through corresponding filter devices and detectors. Finally, the reconstruction unit 250 reconstructs a multi-spectral single-pixel image.

[0034] In one example, the number of imaging lenses, filter devices, and detectors is N, where N is more than 2. Preferably, Figure 2 As shown, there are more than 3. By increasing the number of filter devices, more spectral information can be observed. The upper limit of N can be the maximum value of the imaging lens and the detector that can be placed on the encoding code disk 220 in actual application, which is related to the area size of the encoding code disk 220 and the size of the detector and the imaging lens. The corresponding spectrum can also be increased according to different needs.

[0035] In one example, the imaging lenses 212, 214, 216, etc. are lenses with the same optical parameters (focal length, viewing angle, resolution, light flux, aperture factor, etc.), such as color imaging lenses. The imaging lenses can gather light to reduce the target object and image it on the mask of the encoding code disk 220. The multiple imaging lenses can respectively image the object to be measured on different encoding positions of the circular encoding code disk ( Figure 2 The numbers 1, 2, and 3 on the coding disk indicate three position areas).

[0036] In this embodiment, imaging is achieved by sharing one encoding code disk with multiple imaging lenses, and each channel occupies one spectrum through a corresponding filter device (such as a filter), which has low requirements on the achromatic ability of the lens and can improve the flux of each spectrum. Compared with the solution of using a shared lens and then splitting the light, since splitting the light will cause light loss, the single lens single spectral channel method adopted in this embodiment can effectively improve the light flux.

[0037] In one example, a cyclic S matrix is ​​engraved on the encoding code disk 220, which is used to change the intensity of the light beam transmission, thereby spatially encoding the incident light. Compared with the expensive spatial light modulator, the encoding code disk 220 has the advantages of low cost, wide modulation band, and high refresh rate. In some embodiments, according to the actual resolution requirements, each row of the cyclic S matrix M can be constructed as a series of sub-matrices M i (i=1, 2, 3, ..., N, N is a positive integer), the switching of each submatrix corresponds to the switching of each column of coded pixels. Compared with other orthogonal matrices such as the Hadamard matrix, the use of the circulant S matrix can save coding space. During the movement of the mask relative to the target object image, each time the image and the modulation pattern move relative to each other by one column, it is equivalent to switching a submatrix (i.e., a pattern).

[0038] Figure 3 FIG. 1 shows a schematic diagram of the positional relationship between an imaging lens and an encoding code disk according to an example, and specifically shows the corresponding plane positions of three imaging lenses on the encoding code disk. Figure 3 As shown, the encoding code disk 220 is circular, and has a ring-shaped encoding area along its periphery. The cyclic S matrix can be transferred to the encoding area by electron beam evaporation, photolithography, etc. to form a mask pattern.

[0039] Corresponding to the annular mask, the three imaging lenses are also distributed in a circular shape in space, which can reduce the target object to the image of the mask area. During the imaging process, the encoding code disk 220 realizes uniform rotation through a code disk driver (such as a motor or other driving device), so that the image of the target object and the mask on the encoding code disk 220 move relative to each other. In this process, the cyclic S matrix on the mask will modulate the light field in sequence, and the encoding code disk rotates one circle, that is, the cyclic S matrix is ​​scanned once in sequence, to achieve a complete sampling.

[0040] Since all areas covered by the rotating code in the code disk 220 can achieve light field modulation, the inventors of the present invention have found that parallel multi-spectral single-pixel imaging can be achieved through structural design. Figure 2 , filter devices (e.g., filters) 232-236 and single-pixel detectors 242-246 are arranged on the imaging optical path corresponding to each imaging lens, wherein the filter devices 232, 234, 236 correspond to the imaging lenses 212, 214, 216 respectively, and are arranged to transmit spectra of different wavelengths. Since the filters transmit different wavelengths, the receiving target surfaces of the single-pixel detectors 242, 244, 246 corresponding to each filter can receive spectral information of different wavelengths, and then a multi-spectral single-pixel image with different spectral information can be obtained through reconstruction.

[0041] Figure 4 A three-dimensional schematic diagram of the optical path channels and the positions of the code disk according to an example is shown. As shown in the figure, the three optical path channels correspond to a combination of an imaging lens, a filter device and a detector. After passing through the filter device, each optical channel contains spectral information of different wavelengths, and the spectral information is captured and received by the corresponding single-pixel detector. Figure 2 , the detector is set at the end of the optical path, which is used to collect the single-pixel signal corresponding to the spectrum that penetrates the encoding code disk and is optically filtered within a period of time. The single-pixel detector can specifically be a photodetector, which is used to convert the received spectral signal into an electrical signal, such as a voltage or current signal, which represents the light intensity information collected by the detector when the code disk rotates (data on the change of light intensity over time). Using multiple single-pixel detectors to detect spectra of different bands respectively can effectively restore the multi-spectral image of the target scene.

[0042] return Figure 2 The reconstruction unit 250 is connected to each detector via an acquisition card, and can receive the data collected by the multiple detectors 242-246, and is used to process the data to reconstruct a multi-spectral single-pixel image of the object to be measured with different spectral band information.

[0043] In one example, the reconstruction unit 250 can be integrated into a host computer, such as a single-chip microcomputer, a processor, etc. with data calculation and processing capabilities, which can amplify, filter and / or correct the collected detection signal and convert it into a digital signal, and reconstruct the image by matching the light field intensity of the modulated light signal (for example, the detected light intensity information) with the circulant S matrix on the mask of the encoding code disk to obtain image data.

[0044] According to the embodiments of the present application, multi-spectral parallel single-pixel imaging is achieved by adopting multiple filter devices and single-pixel detectors for parallel imaging, which can increase the imaging spectral range and significantly reduce the data acquisition time.

[0045] Figure 5 A schematic diagram of a multi-spectral parallel single-pixel imaging system according to an embodiment of the present application is shown. Figure 2 The systems shown are similar, except for the number of imaging lenses / filters / detectors shown. As described above, by increasing the number of filters, the effect of observing more spectral information can be achieved. The corresponding spectrum can also be increased according to different needs. For example, the number N of imaging lenses, filters and detectors can be 4, 5 or other numbers.

[0046] In this example, a filter device such as a filter is arranged between the encoding code disk and the detector. Preferably, the filter device can be combined with the detector. Filters of different bands are combined with the detector, for example, the filter is installed on the detector. The filter transmits light of different bands and projects spectral information of different wavelengths onto the target surface of the detector, which is received by the detector. The advantage of this embodiment is that the target surface area of ​​the detector can be designed to be smaller, and the size of the filter used is also smaller, which can effectively reduce costs.

[0047] Figure 6 A schematic diagram of a multi-spectral parallel single-pixel imaging system according to another embodiment of the present invention is shown. Figure 5 The system shown is similar, except for the positional relationship of the encoding code disk / filter / detector shown. In this example, as shown in the figure, filter devices such as filters are arranged between the imaging lens and the encoding code disk, that is, the optical path first passes through the filter to obtain a spectrum of different wavelengths, and then passes through the encoding code disk for spatial modulation imaging. In one embodiment, each filter device can be combined with a corresponding imaging lens, for example, the filter and the imaging lens are combined and installed together. Filters of different wavelengths are combined with the imaging lens to reduce the optical information of the object to be measured at different wavelengths and image it on the mask of the encoding code disk. Compared to Figure 5 The imaging system Figure 6The advantage of the illustrated embodiment is that the imaging lens and the filter are easy to disassemble when combined, and the user can replace the imaging lens with filters of different wavelengths by himself, thereby facilitating the observation of different targets.

[0048] Figure 7 A flowchart of a multi-spectral parallel single-pixel imaging method according to an embodiment of the present application is shown. As shown in the figure, the imaging method may include the following steps:

[0049] Step 310: The object to be measured is imaged to different positions on the mask of the encoding code disk through one or more imaging lenses.

[0050] Taking multiple imaging lenses as an example, refer to Figure 2 , the target object is imaged by imaging lenses 212, 214, and 216, and the imaging lenses respectively image the target object to different positions on the mask of the encoding code disk. A cyclic S matrix M is engraved on the encoding code disk, which can spatially modulate the light field of the image at each position. According to the actual resolution requirements, the matrix M can be regarded as a series of matrices M i (i=1, 2, 3, ..., N, N is a positive integer), and the switching of each matrix corresponds to the switching of a column of coded pixels.

[0051] Step 320 , driving the encoding code disk to rotate at a constant speed, so that a relative displacement occurs between the mask on the encoding code disk and the image of the object to be measured, until all encoding areas of the encoding code disk are measured relative to the object to be measured.

[0052] In one example, a brushless motor or the like can be used to drive the encoder disk to rotate at a constant speed, which can ensure that the encoder disk rotates at a constant and stable speed at a high speed. During the relative movement between the image of the target object and the mask on the encoder disk, the two move relative to each other by one column of encoded pixels, and the matrix M on the mask i When the encoding code disk rotates one circle relative to the image of the object to be measured (i.e., a series of cyclic S matrices are scanned in sequence), a complete sampling of single-pixel imaging is completed, thereby realizing the measurement of the target object to be measured.

[0053] Step 330, using at least two filter devices to selectively transmit light of different wavelength bands for the light signal passing through the imaging lens or the mask and respectively receiving them by corresponding single-pixel detectors; and processing the data collected by the detector to reconstruct a multispectral image of the object to be measured.

[0054] In one example, refer to Figure 5 , the image of the object to be measured modulated by the mask passes through filters of different wavelengths and is received by photodetectors respectively; alternatively, referring to Figure 6Alternatively, the optical signal after the imaging lens may be optically filtered and then modulated by the encoding code disk, and the modulated spectral signals are then received by the photodetectors. In other words, this embodiment does not limit the order of steps 320 and 330.

[0055] Reference Figure 5-6 After receiving the modulated light signal, each photodetector can convert it into an electrical signal and send it to the reconstruction processing unit, which can correspond the modulated light signal to the cyclic S matrix on the encoding code disk mask to reconstruct the image.

[0056] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0057] The block diagrams of the devices, apparatuses, equipment, and systems involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.

[0058] It should also be noted that in the apparatus, device and method of the present application, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0059] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0060] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A multi-spectral parallel single-pixel imaging system, comprising: One or more imaging lenses, at least two filter elements, at least two detectors, an encoding code disk, and a code disk driver; Wherein, the number of the filter devices and the number of the detectors are the same; The imaging lens is used to image the object to be measured onto the encoding position of the encoding code disk; The filter device is used to filter the light passing through the imaging lens; The detector is a single-pixel detector, used to receive the light signal transmitted through the corresponding filter device; The code disk driver is configured to drive the encoding code disk to rotate at a constant speed, so as to achieve relative movement between the image of the object to be measured and the mask on the encoding code disk.

2. The imaging system according to claim 1, wherein: The imaging system further comprises a reconstruction unit, wherein the reconstruction unit is configured to receive data collected by the at least two detectors, and to process the data to reconstruct images of the object to be detected in different spectral bands.

3. The imaging system according to claim 1 or 2, wherein: The filtering devices are optical filters, each of which selectively transmits a spectrum of different wavelengths.

4. The imaging system according to claim 1 or 2, wherein: The filter element is disposed between the encoder code disk and the detector.

5. The imaging system according to claim 4, wherein: The filter device is combined with the detector.

6. The imaging system according to claim 1 or 2, wherein: The filter element is arranged between the imaging lens and the encoding code disk.

7. The imaging system according to claim 6, wherein: The filter device is combined with the imaging lens.

8. The imaging system according to claim 1 or 2, wherein: The number of the filter devices and detectors is preferably 3 or more.

9. The imaging system according to claim 1 or 2, wherein: A cyclic S matrix is ​​engraved on the mask of the encoding code disk.

10. An imaging method comprising: The object to be measured is imaged to different positions on the mask of the encoding code disk through one or more imaging lenses; The encoding code disk is driven to rotate at a constant speed, so that a relative displacement is generated between the mask on the encoding code disk and the image of the object to be measured, until all encoding areas of the encoding code disk are measured relative to the object to be measured; The optical signals passing through the imaging lens or the mask are selectively transmitted with light of different wavelength bands by at least two filter devices and received by corresponding single-pixel detectors respectively; and the data collected by the detectors are processed to reconstruct a multi-spectral image of the object to be measured.

Images