Optical differential imager, imaging system and optical differential method

Abstract

The invention relates to the technical field of target recognition and information optics, in particular to an optical differential imager, an imaging system and an optical differential method.The optical differential imager comprises a micro-nano optical device and an image collector, and the micro-nano optical device is used for conducting phase modulation on an image of an object so as to recover the linear corresponding relation between a frequency spectrum component and an angular spectrum component; the angular spectrum transmittance modulation module is used for carrying out angular spectrum transmittance modulation on the phase-modulated image so as to filter out an angular spectrum low-frequency component of the phase-modulated image; and the image collector is used for collecting a differential image imaged by the micro-nano optical device after optical differential modulation. The system can be easily integrated in any optical imaging system, and the quality and the size of the imaging system are hardly influenced; and when the lens is integrated with an imaging system, the field angle and the resolution of the original imaging system cannot be reduced.

Description

Technical Field

[0001] This invention relates to the fields of target recognition technology and information optics technology, specifically to an optical differential imager, an imaging system, and an optical differential method. Background Technology

[0002] With the rapid development of intelligent decision-making, autonomous driving, and public safety, the demand for fast-sensing and processing of optical image information is increasing rapidly. Especially with the explosive growth in data volume, the traditional "sampling first, processing later" approach to optical image information sensing places immense pressure on backend computing. Image edge extraction is a crucial step in image information processing. Optical image edge detection, based on the principle of optical differentiation, offers advantages over traditional methods, including higher speed, lower energy consumption, parallel processing capabilities, and larger information capacity. It is gradually becoming a key technology for improving the resolution of visual systems and the speed of machine recognition.

[0003] With the trend of device miniaturization and integration, the work on optical differentiation based on micro-nano optical devices has developed rapidly in recent years. At present, the research is still limited by the design of metasurface modulation functions and the implementation principle of multilayer dielectric coupling, which has the disadvantages of insufficient integration and limited application scenarios and field of view.

[0004] Therefore, there is a need to provide an optical differential imager, an imaging system, and an optical differential method to solve the above problems. Summary of the Invention

[0005] To address the limitations of existing technologies, such as insufficient integration, restricted application scenarios, and limited field of view due to the design of metasurface modulation functions and the implementation principle of multilayer dielectric coupling, this invention provides an optical differential imager, an imaging system, and an optical differential method to solve these problems.

[0006] The first aspect of the present invention provides an optical differential imager employing the following technical solution, comprising: Micro-nano optical devices are used to phase modulate the image of an object to restore the linear correspondence between the spectral components and the angular spectral components, and to modulate the angular spectral transmittance of the phase-modulated image to filter out the low-frequency angular spectral components of the phase-modulated image. And an image acquisition device, which is used to acquire differential images formed by optical differential modulation of micro-nano optical devices.

[0007] A further technical solution of the present invention is that the micro-nano optical device includes two metasurfaces integrated together. One metasurface is used to perform phase modulation on the image of an object to restore the linear correspondence between the spectral components and the angular spectral components. The other metasurface is used to perform angular spectral transmittance modulation on the phase-modulated image to filter out the low-frequency angular spectral components of the phase-modulated image.

[0008] A further technical solution of the present invention is that the micro-nano optical device includes a metasurface, on which phase modulation and angular spectral transmittance modulation are integrated to perform phase modulation on the image of an object to restore the linear correspondence between the spectral components and the angular spectral components, and to perform angular spectral transmittance modulation on the phase-modulated image to filter out the low-frequency angular spectral components of the phase-modulated image.

[0009] A further technical solution of the present invention is that the phase modulation function of the micro / nano optical device is:

[0010] In the formula, Represents the real space of micro / nano optical devices The phase modulation function of the position; This represents the length characteristic parameter of the imaging system; Indicates the imaginary part; Indicates wave number.

[0011] A further technical solution of the present invention is that the angular spectral transmittance function of the micro / nano optical device is:

[0012] In the formula, The angular spectral transmittance function representing micro / nano optical devices; Indicates and x The angle between directions; Indicates and y The angle between directions; Indicates wavelength; Indicates the transmittance coefficient; express x Angular spectrum magnitude of direction; express y The magnitude of the angular spectrum in the direction.

[0013] A further technical solution of the present invention is that micro-nano optical devices are attached to the image plane of the image acquisition device.

[0014] A second aspect of the present invention provides an imaging system including an optical differential imager provided in the first aspect of the present invention, wherein the optical differential imager is disposed on the image plane of the imaging system, wherein the side of the micro-nano optical device facing away from the image acquisition device faces the image plane of the imaging system.

[0015] A further technical solution of the present invention is that the imaging system is a single-lens imaging system, and the length characteristic parameter of the single-lens imaging system is the distance from the image plane of the image acquisition device to the back focal plane of the lens.

[0016] A further technical solution of the present invention is that the imaging system is a multi-lens imaging system, and the length characteristic parameter of the multi-lens imaging system is the distance from the image plane of the image acquisition device to the back focal plane of the multi-lens imaging system.

[0017] A third aspect of the present invention provides an optical differentiation method based on an optical differential imager on the image plane, characterized in that the optical differential imager provided in the first aspect of the present invention is used to perform optical differential processing on the image formed by the imaging system and to acquire a differential image.

[0018] The beneficial effects of this invention are: This invention designs an optical differential imager, utilizing micro- and nano-optical devices to phase-modulate the image of an object, thereby restoring the linear correspondence between spectral and angular spectral components. Furthermore, it modulates the angular spectral transmittance of the phase-modulated image to filter out low-frequency components of the angular spectrum. Then, the image acquisition unit of the optical differential imager acquires the differential image formed by the optical differential modulation of the micro- and nano-optical devices. This invention is easily integrated into any optical imaging system with minimal impact on the system's quality and size. Moreover, when integrated with an imaging system, this invention does not reduce the original imaging system's field of view or resolution. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of an optical differential imager according to the present invention; Figure 2 This is a spectrum analysis diagram of the image captured by the single-lens imaging system using an optical differential imager in an embodiment of the present invention. Figure 3 This is a spectral transmittance function distribution diagram of the micro / nano optical device in an embodiment of the present invention; Figure 4 This is a phase modulation function distribution diagram of the micro / nano optical devices in an embodiment of the present invention; Figure 5 This refers to the numerical calculation results of the single-lens imaging system when using an optical differential imager in an embodiment of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] An embodiment of the optical differential imager of the present invention, such as... Figure 1 As shown, it includes: micro-nano optical devices and an image acquisition device. The micro-nano optical devices are used to perform phase modulation on the image of an object to restore the linear correspondence between the spectral components and the angular spectral components, and to perform angular spectral transmittance modulation on the phase-modulated image to filter out the low-frequency angular spectral components of the phase-modulated image. The image acquisition device is used to acquire the differential image formed by the optical differential modulation of the micro-nano optical devices.

[0023] For example, in one specific embodiment, the micro / nano optical device includes two metasurfaces integrated together. One metasurface is used to perform phase modulation on the image of an object to restore the linear correspondence between the spectral components and the angular spectral components. The other metasurface is used to perform angular spectral transmittance modulation on the phase-modulated image to filter out the low-frequency components of the angular spectrum of the phase-modulated image.

[0024] For example, in one specific embodiment, the micro / nano optical device includes a metasurface on which phase modulation and angular spectral transmittance modulation are integrated. The metasurface is used to perform phase modulation on an image of an object to restore the linear correspondence between spectral and angular spectral components, and to perform angular spectral transmittance modulation on the phase-modulated image to filter out low-frequency angular spectral components of the phase-modulated image. Figure 2 As shown in (a), after an object is imaged by a lens, the different angular spectral components represented by red, green, and blue rays at the image plane are obtained. Figure 2 The modulation phase shown in (c) has an angular spectrum as follows Figure 2 (a) The frequency shift corresponding to the yellow ray, the angular spectral components recover the angular spectral direction corresponding to the back surface of the object, and then... Figure 2 (c) shows the high-frequency filtering achieved by modulating the angular spectral transmittance.

[0025] For example, in one specific embodiment, the spectral shift of the image during imaging depends on the imaging system. For a single-lens imaging system, the object's spectrum is modulated by the phase of a single lens during imaging, and the correspondence between the angular spectrum and the overall spectrum is complex. A linear correspondence can be restored by adding phase modulation to the image plane. The phase modulation function of the micro / nano optical device is:

[0026] In the formula, Represents the real space of micro / nano optical devices The phase modulation function of the position; This represents the length characteristic parameter of the imaging system; Indicates the imaginary part; The wave number is represented by , where the length characteristic parameter of a single-lens imaging system is the distance from the image plane of the image acquisition device to the back focal plane of the lens, and the length characteristic parameter of a multi-lens imaging system is the distance from the image plane of the image acquisition device to the back focal plane of the multi-lens imaging system.

[0027] For example, in one specific embodiment, after phase modulation of the image of an object, the spectral components of the image correspond linearly to the angular spectral components. The plane wave components at small angles carry the low-frequency information of the object. Since the edge information of the object corresponds to the high-frequency components in the spectrum, by modulating the angular spectrum of the object's image, the small-angle propagation components are eliminated, while the large-angle components are retained. This filters out low-frequency components and retains high-frequency components, achieving edge imaging. Therefore, the angular spectral transmittance function of the micro-nano optical device in this embodiment is:

[0028] In the formula, The angular spectral transmittance function representing micro / nano optical devices; Indicates and x The angle between directions; Indicates and y The angle between directions; Indicates wavelength; Indicates the transmittance coefficient; express x Angular spectrum magnitude of direction; express y The magnitude of the angular spectrum in the direction.

[0029] For example, in one specific embodiment, micro-nano optical devices are attached to the image plane of the image acquisition device.

[0030] An embodiment of an imaging system according to the present invention includes an optical differential imager as described in the present invention. The optical differential imager is disposed on the image plane of the imaging system, wherein the side of the micro-nano optical device facing away from the image acquisition device faces the image plane of the imaging system.

[0031] For example, in one specific embodiment, the imaging system is a single-lens imaging system, and the length characteristic parameter of the single-lens imaging system is the distance from the image plane of the image acquisition device to the back focal plane of the lens.

[0032] For example, in one specific embodiment, the imaging system is a multi-lens imaging system, and the length characteristic parameter of the multi-lens imaging system is the distance from the image plane of the image acquisition device to the back focal plane of the multi-lens imaging system.

[0033] The present invention provides an optical differentiation method based on an optical differential imager on the image plane, which uses the optical differential imager in the embodiments of the present invention to perform optical differential processing on the image formed by the imaging system and to acquire a differential image.

[0034] Working principle An optical differential imager is placed on the image plane of the imaging system. The spectrum of the object changes after it is imaged by the imaging system. The optical differential imager first moves the spectrum of the image, making each spectral component of the object's image linearly correspond to the angular spectrum component. Specifically, the small-angle optical propagation component corresponds to low-frequency information, and the large-angle optical propagation component corresponds to high-frequency information. Then, through angular spectrum modulation, the small-angle optical propagation component is restricted from passing through, thereby filtering out low-frequency components and realizing optical differential operation. Finally, the differential image is acquired by the image acquisition device.

[0035] The present invention will be described below with reference to specific embodiments and accompanying drawings: In this embodiment, the focal length of the imaging lens is used. With a target distance of 10cm and an object distance of 20cm, the modulation function of the micro / nano optical device is obtained as follows: Figure 3 and Figure 4 The results of the numerical calculation are as follows: Figure 5 That is, from Figure 5 It can be seen that the original image of the object is Figure 5 As shown in (a), after being modulated by the imaging lens, the same spectral components of the object no longer propagate in the same direction. The micro-nano optical devices on the image plane first correlate the image's spectrum with its angular spectrum, then perform angular spectrum modulation. By filtering out low-frequency components, they achieve optical differential operations on the image. Finally, the image acquisition device captures the differential image, as shown in [image description missing]. Figure 5 As shown in (b), in comparison Figure 5 (a) and Figure 5 (b) It can be seen that the edges of the differential image are enhanced.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An optical differential imager, characterized in that, include: Micro-nano optical devices are used to phase modulate the image of an object to restore the linear correspondence between the spectral components and the angular spectral components, and to modulate the angular spectral transmittance of the phase-modulated image to filter out the low-frequency angular spectral components of the phase-modulated image. And an image acquisition device, which is used to acquire differential images formed by optical differential modulation of micro-nano optical devices.

2. The optical differential imager according to claim 1, characterized in that, The micro-nano optical device includes two metasurfaces integrated together. One metasurface is used to perform phase modulation on the image of the object to restore the linear correspondence between the spectral and angular spectral components. The other metasurface is used to perform angular spectral transmittance modulation on the phase-modulated image to filter out the low-frequency components of the angular spectrum of the phase-modulated image.

3. The optical differential imager according to claim 1, characterized in that, Micro-nano optical devices include a metasurface on which phase modulation and angular spectral transmittance modulation are integrated. The metasurface is used to perform phase modulation on the image of an object to restore the linear correspondence between the spectral components and the angular spectral components, and to perform angular spectral transmittance modulation on the phase-modulated image to filter out the low-frequency components of the angular spectrum of the phase-modulated image.

4. An optical differential imager according to claim 1, characterized in that, The phase modulation function of micro / nano optical devices is: In the formula, Represents the real space of micro / nano optical devices The phase modulation function of the position; This represents the length characteristic parameter of the imaging system; Indicates the imaginary part; Indicates wave number.

5. An optical differential imager according to claim 1, characterized in that, The angular spectral transmittance function of micro / nano optical devices is: In the formula, The angular spectral transmittance function representing micro / nano optical devices; Indicates and x The angle between directions; Indicates and y The angle between directions; Indicates wavelength; Indicates the transmittance coefficient; express x Angular spectrum magnitude of direction; express y The magnitude of the angular spectrum in the direction.

6. An optical differential imager according to claim 1, characterized in that, Micro- and nano-optical devices are attached to the image plane of the image acquisition device.

7. An imaging system, characterized in that, The optical differential imager according to any one of claims 1-6 is disposed on the image plane of the imaging system, wherein the side of the micro-nano optical device facing away from the image acquisition device faces the image plane of the imaging system.

8. The imaging system according to claim 7, characterized in that, The imaging system is a single-lens imaging system, and the length characteristic parameter of the single-lens imaging system is the distance from the image plane of the image acquisition device to the back focal plane of the lens.

9. The imaging system according to claim 7, characterized in that, The imaging system is a multi-lens imaging system, and the length characteristic parameter of the multi-lens imaging system is the distance from the image plane of the image acquisition device to the back focal plane of the multi-lens imaging system.

10. An optical differentiation method based on an optical differential imager at the image plane, characterized in that, The optical differential imager according to any one of claims 1-6 is used to perform optical differential processing on the image formed by the imaging system and to acquire a differential image.

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