A visible-light near-infrared tomographic telescopic imaging system

Abstract

The present invention discloses a visible light near-infrared tomographic telescopic imaging system, which belongs to the field of optical imaging detection technology. It includes a telephoto main lens, an electrically controlled liquid crystal micro-optical structure, an array photosensitive detector, a drive control module and a processing module; the telephoto main lens performs a compression imaging of a distant object; the drive control module provides a voltage signal for driving and regulating the array photosensitive detector and the electrically controlled liquid crystal micro-optical structure; the electrically controlled liquid crystal micro-optical structure arranges target light beams in different directions in a discrete manner and converges them on photosensitive elements; the array photosensitive detector converts the characteristic light beam incident on the photosensitive element into an electrical signal; the processing module quantizes the electrical signal from each photosensitive element to obtain a sequence of sub-image data containing three-dimensional spatial information. The present invention establishes an electrical signal-target depth relationship to perform electrically controlled tomographic imaging, thereby further extending the depth of field.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical imaging detection, and more specifically, relates to a visible light near-infrared tomography telescopic imaging system. Background Art

[0002] Along with human cognition of the world, the first telescope was born in Europe in the 17th century. After hundreds of years of development, the imaging quality and types of telescopes have made great progress. At present, telescopic imaging systems are widely used in military detection, astronomical observation and other fields. They can give observers a feeling of "bringing objects closer". The image of a distant object formed by a telescopic imaging system can be observed through an eyepiece or an electronic system.

[0003] Although the overall performance of telescopic imaging systems has been improving, insufficient depth of field is an important defect of traditional telescopic imaging systems. Depth of field refers to the range of object distances in which a clear image can be obtained, measured along the axis of the imaging device in front of the optical imaging system. Due to the telephoto characteristics of the telescopic system, its depth of field is generally small. Without focusing, its depth of field is usually in the order of meters. This greatly limits the application of telescopic imaging systems. The usual practice is to reduce the aperture. Although this can increase the depth of field, the price paid is that the amount of light entering is greatly reduced at the same time, and the cutoff frequency also drops sharply. Summary of the invention

[0004] In view of the defects of the related art, the object of the present invention is to provide a visible light near-infrared tomography telescopic imaging system, aiming to solve the problem of insufficient depth of field of the telescopic imaging system.

[0005] To achieve the above-mentioned object, the present invention provides a visible light near-infrared tomographic telescopic imaging system, comprising a telephoto main lens, an electrically controlled liquid crystal micro-optical structure, an array photosensitive detector, a drive control module and a processing module; wherein the array photosensitive detector is divided into a plurality of sub-array photosensitive detectors, and the sub-array photosensitive detectors include a plurality of photosensitive elements;

[0006] The telephoto main lens performs a compressed image of the distant object;

[0007] The drive control module provides a voltage signal for driving and regulating the planar array photosensitive detector and the electrically controlled liquid crystal micro-optical structure;

[0008] The electrically controlled liquid crystal micro-optical structure arranges target light beams in different directions in a discrete manner and converges them on the photosensitive element;

[0009] The planar array photosensitive detector converts the characteristic light beam incident on the photosensitive element into an electrical signal;

[0010] The processing module quantizes the electrical signal from each photosensitive element to obtain sequence sub-image data containing three-dimensional spatial information, and performs three-dimensional light field tomography imaging by establishing a mathematical relationship between the electrical signal amplitude and the optimal object plane depth.

[0011] Furthermore, when the drive control module adjusts the mean square amplitude of the voltage, the focal length of the electrically controlled liquid crystal micro-optical structure changes, and the optimal object plane position corresponding to the entire imaging system changes, thereby obtaining a mathematical relationship between the electrical signal amplitude and the optimal object plane depth.

[0012] Further, the electrically controlled liquid crystal micro-optical structure comprises a liquid crystal layer, a patterned electrode layer and a common electrode layer;

[0013] The patterned electrode layer and the common electrode layer are respectively arranged on both sides of the liquid crystal layer;

[0014] The patterned electrode layer is composed of a conductive film, on which electrode micropores distributed in an array are arranged. The electrode micropores have more than two aperture sizes, and the electrode micropores with different apertures are arranged alternately, and the electrode micropores with the same aperture are arranged periodically.

[0015] Furthermore, the conductive film is provided with m×n electrode micropores distributed in an array, and the planar array photosensitive detector is correspondingly divided into m×n sub-planar array photosensitive detectors distributed in an array, and m and n are both integers greater than 1.

[0016] Furthermore, the electrode micropores are circular, triangular, square, regular pentagonal or regular hexagonal.

[0017] Furthermore, the common electrode layer includes a conductive light-transmitting film.

[0018] Furthermore, the drive control module loads the driving and regulating voltage signal between the patterned electrode layer and the common electrode layer; when the mean square amplitude of the voltage signal is higher than a preset threshold, the electrically controlled liquid crystal micro-optical structure is equivalent to a planar liquid crystal micro-lens array.

[0019] Compared with the prior art, the above technical solution conceived by the present invention can achieve the following beneficial effects:

[0020] 1. The telescopic imaging system of the present invention can form a specific spatial electric field distribution inside the liquid crystal micro-optical structure under the external voltage excitation of the drive control module, thereby inducing the liquid crystal molecules to form a specific spatial refractive index directional distribution corresponding to the macroscopic micro-lens array. This liquid crystal micro-lens array performs secondary imaging on the image formed by the telephoto objective lens, which can significantly expand the depth of field of the telescopic imaging system, usually to the order of kilometers. In addition, by adjusting the mean square amplitude of the external excitation voltage, the focal length of the liquid crystal micro-optical structure can be adjusted. When the focal length of the liquid crystal micro-optical structure changes, the optimal object plane position corresponding to the entire imaging system will change, so that the relationship between the electrical signal and the target depth can be established, thereby performing electrically controlled tomographic imaging and further expanding the depth of field.

[0021] 2. The operation of controlling the focal length of the liquid crystal microlens by stimulating a specific spatial electric field is subject to the constraints, intervention or guidance of an external voltage and has intelligent characteristics. In addition, the liquid crystal microlens array that can be precisely electrically driven has extremely high stability of structure, electrical and electro-optical parameters and has the characteristics of high control accuracy.

[0022] 3. The main body of the visible light and near-infrared ultra-depth telescopic imaging system of the present invention is a liquid crystal microlens array encapsulated in a chip housing, the functional thickness of which is only in the micron order, which is convenient for plugging in the optical path and easy to match and couple with conventional optical optoelectronic mechanical structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the packaging structure of the visible light near-infrared tomography telescopic imaging system according to an embodiment of the present invention;

[0024] Figure 2 1 is a schematic diagram of an optical imaging application configuration of a visible light near-infrared tomography telescopic imaging system according to an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of the electrically controlled liquid crystal micro-optical structure of the visible light near-infrared tomography telescopic imaging system according to an embodiment of the present invention;

[0026] Figure 4 is a schematic diagram of a liquid crystal microlens array having different light focusing capabilities under different driving electrical signals;

[0027] Figure 5 This is a typical schematic diagram of the electrode micropore structure;

[0028] Figure 6 is a schematic diagram showing that the focal length of the liquid crystal microlens array varies with the amplitude of the driving voltage signal;

[0029] Figure 7 It is a schematic diagram of the relationship between the electrical signal amplitude and the optimal object plane depth. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] To achieve the above-mentioned object, the present invention provides a visible light near-infrared tomographic telescopic imaging system, comprising a telephoto imaging objective lens, an electrically controlled liquid crystal micro-optical structure, a planar array photodetector, a drive control module and a processing module;

[0032] Among them, the telephoto imaging objective lens is used to compress and image distant objects once; the electrically controlled liquid crystal micro-optical structure can form a parabolic gradient refractive index distribution under the driving voltage signal, so that it is macroscopically manifested as an electrically controlled microlens array; the surface array photodetector includes a plurality of array-distributed sub-surface array photodetectors, and each sub-surface array photodetector includes a plurality of array-distributed photosensitive elements with the same number and arrangement; the surface array electrically controlled liquid crystal microlens array is matched and coupled with the surface array photodetector, and each unit electrically controlled liquid crystal microlens corresponds to a sub-surface array photodetector, forming an imaging monocular in the electrically controlled compound eye imaging detection mode; the surface array electrically controlled liquid crystal microlens array is used to separate target light beams in different directions The light beams are dispersedly arranged and directionally converged on the photosensitive elements of the sub-array photodetectors corresponding to the electrically controlled liquid crystal microlenses of each unit; the array photodetectors convert the characteristic light beams incident on the multiple sub-array photodetectors into electrical signals; the processing module is used to attribute the electrical signals of the photosensitive elements of each sub-array photodetector to the imaging operation of a single eye, and obtain sequence sub-image data containing three-dimensional spatial information by quantizing and processing the photoelectric signals of the sub-array photodetectors; the drive control module can also be used to provide drive and control signals for the array photodetectors and the electrically controlled liquid crystal micro-optical structure, drive the two to work, and perform signal control related to amplitude and frequency on the electrically controlled liquid crystal micro-optical structure.

[0033] Preferably, the planar electrically controlled liquid crystal microlens array and the sub-planar array photoelectric detectors are both M×N elements, wherein M and N are both integers greater than 1.

[0034] The contents involved in the above embodiment are described below in conjunction with a preferred embodiment.

[0035] Figure 1Schematic diagram of the packaging structure of the visible light near-infrared tomography telescopic imaging system of the embodiment of the present invention. As shown in the figure, the electrically controlled liquid crystal micro-optical structure 2 and the array photosensitive detector 3 are coaxially arranged in sequence and packaged in the ceramic housing 1, and the parallel line for providing the control signal and the drive signal is connected by the port 4. The indicator light 5 is used to indicate the working state. When in the normal working state, the indicator light 5 flashes. A flange 6 is provided on the top of the ceramic housing 1 for connecting the telephoto main lens 7 to transmit the external incident light field to the electrically controlled liquid crystal micro-optical structure to perform light control operation.

[0036] Figure 2 : is a schematic diagram of the optical imaging application configuration of the visible light near-infrared tomographic telescopic imaging system of an embodiment of the present invention. As shown in the figure, the electrically controlled liquid crystal micro-optical structure 2 is located between the telephoto main lens 7 and the array photosensitive detector 3. The telephoto main lens 7 compresses the external incident light field once for imaging, and the compressed external incident light field is further converged by the electrically controlled liquid crystal micro-optical structure 2 and projected onto the corresponding sub-array photosensitive detector 3. In addition, by adjusting the mean square amplitude of the voltage applied to the electrically controlled liquid crystal micro-optical structure 2, the electrical control efficiency of the macro focal length can be generated, thereby corresponding to different optimal object planes to achieve tomographic imaging.

[0037] Figure 3 Schematic diagram of the electrically controlled micro-optical structure in the visible light near-infrared tomography telescopic imaging system of the embodiment of the present invention. As shown in the figure, the electrically controlled liquid crystal micro-optical structure includes a liquid crystal layer 24, a first liquid crystal orientation layer 25, a patterned electrode layer 26, a first substrate 27 and a protective anti-reflection film 28 arranged on the upper surface of the liquid crystal layer in sequence, and a second liquid crystal orientation layer 23, a common electrode layer 22 and a second substrate 21 arranged on the lower surface of the liquid crystal layer 24 in sequence. Among them, the liquid crystal layer has a micron-level thickness, the liquid crystal orientation layer has a nanometer-level thickness, the substrate is a quartz substrate of hundreds of microns, and the protective anti-reflection film is exposed to the outside through the flange 6 on the ceramic housing 1 to receive the incident light field.

[0038] The electrically controlled liquid crystal micro-optical structure can be expressed as a planar array of electrically controlled liquid crystal micro-lenses depending on the voltage signal applied. Specifically, its main functional structures include: (i) a top substrate structure with protective anti-reflection films and pattern electrodes on the upper and lower surfaces respectively; (ii) a bottom substrate structure with a common electrode on the outer surface of one side; (iii) a micron-thick liquid crystal material filled between the two substrates. The figure also shows the structural configuration of a planar array photosensitive detector that matches the electrically controlled liquid crystal micro-optical structure. When the mean square amplitude of the signal voltage loaded between the patterned electrode layer and the common electrode layer is greater than the threshold, the stimulated spatial electric field can exert a steering effect on the liquid crystal molecules. The steering degree of the liquid crystal molecules is affected by the strength and direction of the electric field, and the electrically controlled liquid crystal micro-optical structure will be expressed as a planar array of electrically controlled liquid crystal micro-lenses. In the figure, a refractive micro-lens array with a convex contour is used to vividly display the refractive index distribution characteristics of the liquid crystal convergence micro-lens. Figure 4 The figure shows a liquid crystal microlens array with different light focusing capabilities under different driving electrical signals.

[0039] The common electrode layer is composed of a conductive light-transmitting film, such as Figure 5 As shown, the patterned electrode layer 26 is composed of a conductive film 262, and the conductive film is provided with electrode micropores 261 distributed in an m×n array (where m and n are both integers greater than 1), and electrode micropores of different apertures are arranged alternately, and electrode micropores of the same aperture are arranged periodically. Two or more electrode micropores with two or more apertures are provided in the conductive film. It should be noted that the electrode micropores arranged alternately periodically in this embodiment can be composed of two or more micropores with different apertures; in addition, the micropores can be circular holes, triangular holes, square holes, regular pentagonal holes, regular hexagonal holes, etc.

[0040] When the mean square amplitude of the signal voltage loaded between the patterned electrode layer and the common electrode layer is higher than the threshold, the electrically controlled liquid crystal micro-optical structure is equivalent to a planar array of liquid crystal microlenses. The planar array of electrically controlled liquid crystal microlenses is composed of unit electrically controlled liquid crystal microlenses distributed in an m×n element array. The unit electrically controlled liquid crystal microlenses correspond to the electrode microholes one by one. Each electrode microhole is located at the center of the corresponding unit electrically controlled liquid crystal microlens, forming the upper electrode of the unit electrically controlled liquid crystal microlens. The lower electrodes of all unit electrically controlled liquid crystal microlenses are provided by the common electrode layer. The planar array photosensitive detector is divided into sub-planar array photosensitive detectors distributed in an m×n element array. There is a one-to-one correspondence between the sub-planar array photosensitive detectors and the unit electrically controlled liquid crystal microlenses to avoid crosstalk.

[0041] The following is a detailed description of the working process of the visible light near-infrared tomography telescopic imaging system of the embodiment of the present invention. First, a group of parallel lines that can provide drive control, control signals and data transmission are connected to the port, and then the drive control signals for the array photosensitive detector and the timing voltage signals with characteristic frequency, amplitude and duty cycle for driving the electronically controlled liquid crystal micro-optical structure are respectively input. At this time, the imaging system works in the three-dimensional light field imaging mode; the image data collected is output through the parallel lines connected to the port; during the above working process, the indicator light flashes continuously.

[0042] Specifically, when the signal voltage loaded between the patterned electrode layer and the common electrode layer is higher than a certain threshold value, the liquid crystal molecules in the liquid crystal layer form a specific spatial arrangement under the control of the electric field, thereby generating a gradient equivalent refractive index distribution for the singular light. The electrically controlled liquid crystal micro-optical structure is macroscopically equivalent to a planar electrically controlled liquid crystal microlens array, and the spatial resolution of its clear imaging is determined by the scale of the planar liquid crystal microlens array. The spatial arrangement of the liquid crystal molecules is modulated by adjusting the mean square amplitude of the signal voltage, thereby modulating the focusing ability of the unit electrically controlled liquid crystal microlenses of the planar liquid crystal microlens array, so that this three-dimensional light field imaging has the efficiency of electrically controlled modulation. By building an optical test system, the relationship between the focal length of the liquid crystal microlens array and the amplitude of the driving voltage signal can be effectively obtained. Usually, under the appropriate driving voltage signal, as the amplitude of the driving voltage signal increases, the focusing ability of the unit liquid crystal microlens gradually increases, thereby causing the effective focal length to gradually decrease. Figure 6 A schematic diagram of the change of the focal length of the liquid crystal microlens array with the amplitude of the driving voltage signal is given; when the focusing ability of the unit liquid crystal microlens changes, it can be known from the knowledge of geometric optics that the optimal object plane corresponding to the imaging system will change. Since the liquid crystal molecules have excellent stability under the control of the external electric field, the mathematical relationship between the amplitude of the electric signal and the depth of the optimal object plane can be established to produce tomographic three-dimensional light field imaging performance. Figure 7 A schematic diagram of the electrical signal amplitude-optimal object plane depth is given.

[0043] The liquid crystal-based light field imaging detection chip with extended depth of field of the present invention adopts an electrically controlled method to drive an electrically controlled liquid crystal micro-optical structure to perform electrically controlled multi-focal length imaging detection performance, and has the characteristics of electrically adjustable focusing ability, tomographic imaging, fast response speed, and secondary extended depth of field.

[0044] It will be easily understood by those skilled in the art that 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 and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A visible light near-infrared tomography telescopic imaging system, characterized in that: It includes a telephoto main lens, an electrically controlled liquid crystal micro-optical structure, an array photosensitive detector, a drive control module and a processing module; wherein the array photosensitive detector is divided into a plurality of sub-array photosensitive detectors, and the sub-array photosensitive detectors include a plurality of photosensitive elements; The telephoto main lens performs a compressed image of the distant object; The drive control module provides a voltage signal for driving and regulating the planar array photosensitive detector and the electrically controlled liquid crystal micro-optical structure; The electrically controlled liquid crystal micro-optical structure arranges target light beams in different directions in a discrete manner and converges them on the photosensitive element; The planar array photosensitive detector converts the characteristic light beam incident on the photosensitive element into an electrical signal; The processing module quantizes the electrical signal from each photosensitive element to obtain sequence sub-image data containing three-dimensional spatial information, and performs three-dimensional light field tomography imaging by establishing a mathematical relationship between the electrical signal amplitude and the optimal object plane depth.

2. The visible-light near-infrared tomography telescopic imaging system according to claim 1, characterized in that: When the drive control module adjusts the mean square amplitude of the voltage, the focal length of the electrically controlled liquid crystal micro-optical structure changes, and the optimal object plane position corresponding to the entire imaging system changes, thereby obtaining a mathematical relationship between the electrical signal amplitude and the optimal object plane depth.

3. The visible-light near-infrared tomography telescopic imaging system according to claim 1, characterized in that: The electrically controlled liquid crystal micro-optical structure comprises a liquid crystal layer, a patterned electrode layer and a common electrode layer; The patterned electrode layer and the common electrode layer are respectively arranged on both sides of the liquid crystal layer; The patterned electrode layer is composed of a conductive film, on which electrode micropores distributed in an array are arranged. The electrode micropores have more than two aperture sizes, and the electrode micropores with different apertures are arranged alternately, and the electrode micropores with the same aperture are arranged periodically.

4. The visible-light near-infrared tomography telescopic imaging system according to claim 3, characterized in that: The conductive film is provided with m×n electrode micropores distributed in an array, and the surface array photosensitive detector is correspondingly divided into m×n sub-surface array photosensitive detectors distributed in an array, and m and n are both integers greater than 1.

5. The visible-light near-infrared tomography telescopic imaging system according to claim 4, characterized in that: The electrode micropores are circular, triangular, square, regular pentagonal or regular hexagonal.

6. The visible-light near-infrared tomography telescopic imaging system according to claim 3, characterized in that: The common electrode layer includes a conductive light-transmitting film.

7. The visible-light near-infrared tomography telescopic imaging system according to claim 3, characterized in that: The drive control module loads the driving and regulating voltage signal between the patterned electrode layer and the common electrode layer; when the mean square amplitude of the voltage signal is higher than a preset threshold, the electrically controlled liquid crystal micro-optical structure is equivalent to a planar liquid crystal micro-lens array.

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