CN109005318A - A kind of bionical vision system improving brightness of image - Google Patents

Abstract

The invention discloses a kind of bionical vision systems for improving brightness of image, including sequentially connected light source (1), optical imaging system (2), bionical twilight image booster (3) and post processing system (4), in which: the post processing system (4) further includes plane ccd image sensor (41), computer processing unit (42) and image processing algorithm module (43)；(2, bionical twilight image booster (3) and plane ccd image sensor (4) are coaxial for the optical imaging system, effect is provided independently between three, and plane ccd image sensor (4) is located at the focal plane of optical imaging system (1)；Bionical twilight image booster (3) is located at the front end of plane ccd image sensor (4) and is close to plane ccd image sensor (4).Invention achieves brightness of image to improve 5.61 times, and brightness of image improves the positive technical effect that the uniformity of multiple is 95.30%.

Description

A Bionic Vision System for Improving Imaging Brightness

technical field

The invention relates to the technical field of bionic vision, in particular to a bionic vision system for improving imaging brightness.

Background technique

Humans use their eyes to obtain image information from the surrounding environment to understand this complicated world. Accurate observation and recognition of objects requires sufficient brightness. However, due to the low light sensitivity of the retinal structure of the human eye, it cannot Sufficient "exposure", so the human eye cannot accurately observe and identify objects in low-light environments such as night. With the advancement and development of artificial lighting system technology, the low-light environment has been greatly improved, but it is still not possible to make the night as bright as day anytime and anywhere. For example, when traveling at night, the light is still very dim compared with daytime. In addition, not all situations require sufficient light. For example, the development of traditional film requires an airtight darkroom; some optical experiments also need to be carried out in a dark environment, because the surrounding stray light will largely Affect the experimental results; night combat is an effective method of using dark environment conditions to eliminate the enemy commonly used in the military. It is necessary to accurately identify the enemy in a dark environment. These special situations need to be carried out in a dark environment, and accurate observation and observation are also required. Identify objects.

Humans are eager to observe and identify objects in low-light environments. With the development of photoelectric technology, people have developed low-light night vision equipment with the help of photoelectric imaging devices. Weak natural light radiates through the target surface, enters the night vision device, and focuses on the photocathode surface of the image intensifier (coinciding with the rear focal plane of the objective lens) under the action of the strong optical objective lens to excite photoelectrons; Under the action of the system, it is accelerated, focused, imaged, and bombards the fluorescent screen of the image intensifier at a high speed, and excites enough visible light to turn a distant target illuminated by weak natural light into visible light suitable for human eyes. The image is further magnified by the eyepiece to realize low-light environment observation and target identification. The low-light night vision device in the patent application number 2016107322240 "A Military Imitation Strong Light Low-light Night Vision Device" includes a fuselage, a lens, an eyepiece and an objective lens. An image intensifier is installed inside the fuselage to realize image display under low-light conditions; a strong light filter is installed on the objective lens to resist strong light more flexibly and meet the needs of the battlefield. At present, this traditional low-light night vision technology is mainly used in many military fields such as night reconnaissance, photography, observation and aiming, imaging guidance, early warning, fire control, navigation, vehicle driving, field repair, engineering rescue and field rescue; satellite remote sensing , telemetry astronomical galaxy, night observation of weak stars and other astronomical fields.

At present, the principle of traditional low-light night vision equipment is complex, the structure is compact, and it is not portable enough. At the same time, the traditional low-light night vision technology relies on the properties of photoelectric physical materials and the processing time and accuracy of image processing algorithms. The cost is high, power consumption is high, and the application environment is not wide enough. .

The visual system theory based on bionics has developed rapidly in recent years. It is a frontier field integrating optics, electricity, mechanics, biology, computer and informatics. The biological visual system in nature has a unique visual system structure and retinal cortex mapping mechanism. Compared with the human visual system, it has the characteristics of wide field of view, sensitivity to moving targets, rapid resolution adjustment, high imaging brightness, and strong low-light response. Can accurately observe and identify objects. Patent application number 2013106935200 "Multi-field bionic compound eye low-light imaging system based on multi-microfacet optical fiber panel" designed a compound eye-like vision system to realize a miniaturized, lightweight, and large field of view low-light night vision imaging observation system. Patent application number 2016110472826 "An Underwater Polarization Image Fusion System Based on Bionic Vision Mechanism" imitates the visual polarization perception mechanism of mantis shrimp to extract underwater polarization images, effectively improving the clarity and contrast of underwater polarization images, which is beneficial to underwater targets detection and analysis. Patent application number 2017104006246 "An Electronic Compound Eye System Based on Bionic Vision Mechanism" imitates the visual system mechanism of fruit fly compound eyes and is applied to high-end fields such as high-speed target recognition and tracking. In terms of the ability to accurately observe and recognize objects in a low-light environment, due to the unique retinal structure in the elephant trunk fish's visual system, the low-light response ability of the human eye is far inferior to that of the elephant trunk fish's visual system. The present invention simulates the retinal structure in the elephant trunk fish visual system, and proposes a bionic visual system that improves imaging brightness. This system is a brand-new optical design that improves imaging brightness. It has simple principle, simple structure, independent method and light weight. Small in size and widely used in a wide range of environments, it can effectively improve imaging brightness and enhance low-light response.

Contents of the invention

In view of the weak low-light response status of the human visual system, and the traditional low-light night vision technology’s complex principle, compact structure, heavy weight and large volume, limited application environment, and over-reliance on the limitations of physical material properties and image processing algorithms in optoelectronic systems, this paper The invention proposes a bionic vision system that improves imaging brightness, and uses a bionic low-light image intensifier composed of a compound parabolic concentrator array to realize the improvement of imaging brightness.

A bionic vision system for improving imaging brightness of the present invention, the system includes sequentially connected light source 1, optical imaging system 2, bionic low-light image intensifier 3 and post-processing system 4, wherein: said post-processing system 4 Also comprise planar CCD image sensor 41, computer processing unit 42 and image processing algorithm module 43; Described optical imaging system 2, bionic low-light image intensifier 3 and planar CCD image sensor 4 are coaxial, and effect is set independently among the three , the planar CCD image sensor 4 is located at the focal plane of the optical imaging system 1;

The light source 1 is used to provide an illumination source for the system;

The optical imaging system 2 is used to realize optical imaging;

The bionic low-light image intensifier 3 is used to improve imaging brightness and enhance low-light response;

The planar CCD image sensor 41 is used to convert the optical signal into an analog current signal, and the current signal is amplified and converted from analog to digital to realize image acquisition;

The computer processing unit 42 is used to realize storage and transmission of images;

The image processing module 43 is used for final image processing.

The bionic low-light image intensifier 3 includes a compound parabolic concentrator array composed of multiple substructures, each of which is a compound parabolic concentrator; each compound parabolic concentrator is composed of micron-scale parabolic The light enters from the entrance of the compound parabolic concentrator and is reflected by the inner surface of the compound parabolic concentrator. The light is guided to the photosensitive area of the cone, so that the imaging brightness of the photosensitive area of the cone is improved, and the low-light response is enhanced.

The compound parabolic concentrator includes three parameters which determine the geometric structure of the compound parabolic concentrator: the diameter of the entrance, the diameter and the height of the exit.

The compound parabolic concentrator is manufactured by using materials with high transmittance of visible light through laser processing and coating with reflective film.

The optimized parameters of the compound parabolic concentrator are: the diameter of the entrance is 50 μm, the diameter of the exit is 10 μm, and the height is 90 μm.

Compared with the prior art, a bionic vision system for improving imaging brightness of the present invention has achieved the positive technical effect that the imaging brightness is increased by 5.61 times, and the uniformity of the imaging brightness improvement multiple is 95.30%.

Description of drawings

Fig. 1 is a kind of overall structure schematic diagram of the bionic vision system that improves imaging brightness that the present invention proposes;

Fig. 2 is a schematic diagram of the imaging process of a bionic vision system that improves imaging brightness proposed by the present invention;

Figure 3 is a ray tracing diagram of a compound parabolic concentrator;

Fig. 4 is a schematic diagram of a plane array of a compound parabolic concentrator;

Figure 5 is an imaging simulation diagram;

Fig. 6 is a sectional view of a compound parabolic concentrator.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in FIG. 1 , it is a schematic diagram of the overall structure of a bionic vision system for improving imaging brightness according to the present invention. The system includes a light source 1 , an optical imaging system 2 , a bionic low-light image intensifier 3 and a post-processing system 4 . The post-processing system 4 includes a planar CCD image sensor 41 , a computer 42 and an image processing algorithm 43 . The light source 1 is used to provide the lighting source for the system; the optical imaging system 2 is used to realize optical imaging; the bionic low-light image intensifier 3 is used to improve the imaging brightness and enhance the low-light response; the planar CCD image sensor 41 is used to convert the light signal into The current signal is simulated, and the current signal is amplified and converted from analog to digital to realize the acquisition of the image; the computer 42 realizes the storage and transmission of the image; the image processing module 43 performs final processing on the image. The optical imaging system 2 , the bionic low-light image intensifier 3 and the post-processing system 4 function independently and do not affect each other. The optical imaging system 2, the bionic low-light image intensifier 3 and the planar CCD image sensor 4 are coaxial, and the planar CCD image sensor 4 is located at the focal plane of the optical imaging system 2; The front end is close to the plane CCD image sensor 4 .

As shown in FIG. 2 , it is a schematic diagram of the imaging process of a bionic vision system for improving imaging brightness proposed by the present invention. Assuming that the incident light from a distance is parallel light, the incident light from all directions within the field of view range passes through all the optical elements of the optical imaging system 2, and then passes through each compound parabolic concentrator in the bionic low-light image intensifier 3 structure, and then the light is transmitted to the planar CCD image sensor 4, and finally the imaging is completed on the planar CCD image sensor 4. The whole imaging process realizes the improvement of imaging brightness and enhancement of low-light response. The image quality of the imaged image has a certain decline, and the computer 42 completes the image storage and transmission, and the image processing module 43 is used to complete the final processing of the image.

The optical imaging system 2 only plays an imaging role and has no special requirements. A simple optical imaging system such as a thin convex lens may be used, or a complex optical imaging system such as an optical imaging lens group may be used.

The bionic low-light image intensifier 3 is selected to simulate the retinal structure of the elephant trunk fish visual system. In the real structure of the elephant trunk fish retina under the electron microscope, their retinal structure is not smooth, but is composed of small cups on the order of microns, similar to a parabolic reflector, and the inside of this reflective cup is composed of light-reflecting proteins , to guide the light to the photosensitive area of the cone to increase the imaging brightness and enhance the low-light response. Therefore, a micron-scale compound parabolic concentrator model is established, as shown in Figure 3, which is the ray tracing diagram of the compound parabolic concentrator. The light enters from the entrance of the compound parabolic concentrator, is reflected by the inner surface of the compound parabolic concentrator, and converges to the focal plane of the parabolic surface, which is the exit port. Therefore, the bionic low-light image intensifier 3 is located at the front end of the planar CCD image sensor 4 and is close to the planar CCD image sensor 4 . Each compound parabolic concentrator is used to improve imaging brightness and enhance low-light response without affecting each other. It adopts a square planar array closely arranged to form a compound parabolic concentrator planar array, as shown in Figure 4. Schematic diagram of a planar array of parabolic concentrators. (a) (b) are side view and front view respectively, which maximize the use of light energy, and the planar array structure reduces the difficulty of processing. The bionic low-light image intensifier 3 can be manufactured by using materials with high visible light transmittance such as polymethyl methacrylate and glass, through laser processing and coating with reflective film.

Each substructure in the bionic micro-light image intensifier 3 is a compound parabolic concentrator, which includes three parameters of entrance diameter, exit diameter and height, which is the actual design of the compound parabolic concentrator. The key parameters in , determine the geometry of the compound parabolic concentrator and the performance of the bionic low-light image intensifier 2. The size of the compound parabolic concentrator is optimized based on the three evaluation criteria of image continuity, imaging brightness enhancement factor and imaging brightness enhancement factor distribution. The continuity of the image is caused by the inconsistency of the diameters of the entrance and exit of the compound parabolic concentrator, which makes the image discrete, as shown in Figure 5. Enlarge Figure 5, under different incident angles of light, the compound parabolic concentrator increases brightness by different factors. In order to quantify the two evaluation criteria of imaging brightness enhancement multiple and imaging brightness enhancement multiple uniformity, data processing is performed on the brightness enhancement multiple of compound parabolic concentrators with different incident angles, the formula is as follows:

Among them, C is the compound parabolic concentrator with different incident angles to increase the brightness multiple; C _i is the i-th data in C; n is the number of data in C; E(C) is the expected value of C, which means bionic image enhancement The imaging brightness of device 2 is increased by multiples. C _min is the minimum value in C; C _max is the maximum value in C; It is the i-th data after C is normalized; E(C ^* ) is the expected value of the normalized data C ^* ; D(C) is the uniformity of the imaging brightness improvement factor.

The value range of the entrance diameter is 50μm-150μm, the value range of the exit hole diameter is 5μm-30μm, and the height value range is 30μm-130μm. The optimal numerical solution is: the entrance diameter is 50μm; the exit diameter is 10μm; the height is 90μm The profile is shown in Figure 6, the imaging brightness is increased by 5.61 times, and the uniformity of the imaging brightness improvement factor is 95.30%.

The present invention uses the image processing module 6 to perform image processing algorithms such as contrast stretching, pixel filling, and image restoration on the experimental image similar to FIG. 5 to improve image quality.

The present invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solution of the present invention, and the above specific embodiments are only illustrative and not restrictive. Without departing from the gist of the present invention and the scope of protection of the claims, those skilled in the art can also make many specific changes under the inspiration of the present invention, and these all belong to the protection scope of the present invention.

Claims (5)

1. it is a kind of improve brightness of image bionical vision system, which is characterized in that the system include sequentially connected light source (1), Optical imaging system (2), bionical twilight image booster (3) and post processing system (4), in which: the post processing system It (4) further include plane ccd image sensor (41), computer processing unit (42) and image processing algorithm module (43)；It is described (2, bionical twilight image booster (3) and plane ccd image sensor (4) are coaxial, act between three only for optical imaging system On the spot it is arranged, plane ccd image sensor (4) is located at the focal plane of optical imaging system (1)；Bionical twilight image booster (3) it is located at the front end of plane ccd image sensor (4) and is close to plane ccd image sensor (4).

The light source (1) is used to provide lighting source for system；

The optical imaging system (2) is for realizing optical imagery；

The bionical twilight image booster (3) is for improving brightness of image, enhancing low-light response；

The plane ccd image sensor (41) is for converting optical signals into analog current signal, and current signal is by amplification And analog-to-digital conversion, realize the acquisition of image；

The computer processing unit (42) stores and transmits for realizing to image；

Described image processing module (43) is used to carry out final process to image.

2. a kind of bionical vision system for improving brightness of image as described in claim 1, which is characterized in that the bionical low-light It include the compound parabolic concentrator array being made of multiple minor structures in image intensifier (3), each minor structure is one A compound parabolic concentrator；Each compound parabolic concentrator is by the circular platform type noggin of micron dimension being made of paraboloid Composition, light enter from the entrance port of compound parabolic concentrator, reflect by the inner surface of compound parabolic concentrator, light It converges on paraboloidal focal plane i.e. exit portal, it is the same similar to parabolic mirror, guide light into cone photosensitive region, Improve the cone photosensitive region brightness of image, enhancing low-light response.

3. a kind of bionical vision system for improving brightness of image as described in claim 1, which is characterized in that the compound parabolic Face condenser includes the ginseng of three entrance port diameter, exit portal diameter and height decision compound parabolic concentrator geometries Number.

4. a kind of bionical vision system for improving brightness of image as claimed in claim 2 or claim 3, which is characterized in that described compound Parabolic condenser is laser machined and is plated reflectance coating using the higher material of visible light transmittance and completes manufacture.

5. a kind of bionical vision system for improving brightness of image as claimed in claim 2 or claim 3, which is characterized in that described compound The most optimized parameter of parabolic condenser are as follows: 50 μm of entrance port diameter, 10 μm of exit portal diameter, 90 μm of height.