Miniature artificial compound eye imaging system with large depth of field, preparation method and application

Abstract

The invention discloses a large-depth-of-field miniature artificial compound eye imaging system, a preparation method and application, and belongs to the technical field of photoelectric devices. The large-depth-of-field miniature artificial compound eye imaging system comprises a compound eye lens, an objective lens and a microscopic observation system; the objective lens is positioned behind the fly-eye lens and is aligned with the center line of the fly-eye lens; the microscopic observation system is positioned behind the objective lens to receive imaging information; the fly-eye lens comprises a spherical crown base, a central sub-eye, a first circle of sub-eyes and a second circle of sub-eyes. The central sub-eye is located at the vertex of the spherical crown base, and the first circle of sub-eye and the second circle of sub-eye surround the first circle and the second circle of the central sub-eye; a compound eye composed of three different sub-eyes is adopted, and the surface type of each sub-eye is a combination of two lenses with different curvature radiuses; the two lenses with different focal lengths are respectively used for observing images at different distances, so that a compound eye can clearly observe two objects on different planes at the same time; the large-depth-of-field miniature bionic artificial compound eye is prepared with high precision by using a femtosecond laser additive manufacturing technology, and the prepared artificial compound eye is combined with a microscopic observation system, so that the preparation of the large-depth-of-field miniature artificial compound eye imaging system is finally realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic devices, and in particular relates to a micro artificial compound eye imaging system with a large depth of field, a preparation method and an application thereof. Background Art

[0002] After hundreds of millions of years of evolution, arthropods in nature have evolved a visual system consisting of many evenly arranged photosensitive units - compound eyes. Usually, each photosensitive unit is composed of a corneal lens, a cone, a sensory rod bundle, and a optic nerve. The compound eye structure of insects is small in size, has a large field of view, and is sensitive to moving objects, which helps insects obtain environmental information, capture prey, avoid natural enemies, and identify mates. Based on this feature, researchers have prepared a micro-bionic artificial compound eye imaging system that imitates the structure of insect compound eyes, which plays a role in military navigation, intelligent sensing, micro-robot vision, medical endoscopes, and other fields.

[0003] The imaging system usually consists of two parts: the image acquisition system - the compound eye lens and the image receiving system. At present, there are still difficulties in preparing bionic artificial compound eye lenses. In practical applications, it is usually necessary to clearly observe near and far objects at the same time. The traditional single-focal-length compound eye lens knows from the convex lens imaging formula that one object distance corresponds to one image distance, and it is difficult to clearly observe objects on different planes in one area at the same time. To solve this problem, researchers have designed a lens with adjustable focal length, which is driven by electromagnetic force or electrothermal drive. Although the lens can zoom and image, this method has the disadvantages of complex driving mode, slow response time, and limited application environment. So far, how to prepare a high-performance curved compound eye lens that can observe distant and near objects at the same time without being driven is of great significance and challenge. Summary of the invention

[0004] In view of the shortcomings in the prior art, the present invention provides a simple, externally driven, large field of view, large depth of field micro-artificial compound eye imaging system and preparation method. The present invention uses a compound eye composed of three different sub-eyes, wherein the surface of the sub-eye is a combination of lenses with two different curvature radii; the two lenses with different focal lengths respectively observe images at different distances, so that the compound eye can clearly observe two objects in different planes at the same time, thereby solving the problem of limited depth of field of traditional compound eye lenses; then, the "femtosecond laser additive manufacturing" technology is used to prepare a micro-bionic artificial compound eye with a large depth of field with high precision, and the prepared artificial compound eye is combined with a microscopic observation system, finally realizing the preparation of a micro-artificial compound eye imaging system with a large depth of field.

[0005] The present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a micro artificial compound eye imaging system with a large depth of field, comprising a compound eye lens 1, an objective lens 2 and a microscopic observation system 3; wherein the objective lens 2 is located behind the compound eye lens 1 and aligned with the center line of the compound eye lens 1, and the microscopic observation system 3 is located behind the objective lens 2 to receive imaging information; the compound eye lens 1 comprises a spherical crown base 4, a central sub-eye 5, a first circle eye 6 and a second circle eye 7; the central sub-eye 5 is located at the vertex of the spherical crown base 4, and the first circle eye 6 and the second circle eye 7 surround the first circle and the second circle of the central sub-eye 5; wherein the central sub-eye 5, the first circle eye 6 and the second circle eye 7 are all composite lens structures composed of a large lens 8 and a small lens 9; the small lens 9 is located above the large lens 8; the central sub-eye 5, the first circle eye 6 and the second circle eye 7 are all located on the surface of the spherical crown base 4 and the center line angles of adjacent sub-eyes are both The field of view of the fly-eye lens 1 is The focal lengths of the large lens 8 and the small lens 9 vary with the angles between the center lines of the sub-eyes where they are located and the center line of the central sub-eye 5 .

[0007] Furthermore, the focal lengths of the large lenses 8 in the first circle eye 6 and the second circle eye 7 are L2 and L3 respectively, which are calculated by the following formula:

[0008]

[0009] Wherein, L1 is the focal length of the large lens 8 in the central sub-eye 5, R o is the radius of the sphere where the spherical cap base 4 is located, is the field of view of the fly-eye lens 1, It is the included angle between the center lines of adjacent sub-eyes.

[0010] Furthermore, the focal lengths of the small lenses 9 in the central sub-eye 5, the first circle eye 6 and the second circle eye 7 are l1, l2 and l3 respectively, which are calculated by the convex lens imaging formula:

[0011]

[0012] Among them, W min is the minimum object distance.

[0013] Furthermore, L1 is 675.00-800.00 μm, and the field of view is The range is 100°-110°; the minimum object distance is W min The range is 150-675μm.

[0014] Furthermore, the central sub-eye 5, the first circle eye 6 and the second circle eye 7 are closely arranged on the spherical cap base 4; the radius of the central sub-eye 5 is The spherical centers of the large lens 8 and the small lens 9 of the central sub-eye 5, the first circle eye 6 and the second circle eye 7 are respectively on the center lines of the respective sub-eyes and the distance between the spherical centers ranges from 90 to 130 μm.

[0015] In a second aspect, the present invention also provides a method for preparing a micro-artificial compound eye imaging system with a large depth of field, the specific steps of which are as follows:

[0016] (1) Sample preparation;

[0017] The specific steps are as follows: first, drop the optical resin on the substrate; place the substrate on a hot table for preheating, and then cool it naturally at room temperature;

[0018] (2) Leveling processing system;

[0019] Specific steps: Place the prepared substrate in the galvanometer-based femtosecond laser direct writing processing system, adjust the laser energy to the reference value, focus the laser on the interface between the polymer film formed after pre-baking the optical resin and the substrate, rotate the stage support screws so that the spot energy remains unchanged when moving left and right and forward and backward, and the stage is considered to be leveled at this time; then, control the laser to focus on the interface between the optical resin and the substrate and make the focus go deep into the substrate;

[0020] (3) Preparation of micro-artificial compound eyes with large depth of field and integration of imaging systems;

[0021] The specific steps are as follows: generate the point cloud data of the designed micro compound eye lens 1 into the file to be processed; set the laser processing power and perform point-by-point scanning processing; develop, dry and ultraviolet-expose the scanned substrate sheet to finally prepare a micro curved artificial compound eye lens 1 with a large depth of field; finally, seal the compound eye lens 1 and align it with the microscopic observation system 3 to complete the integration of the imaging system.

[0022] Furthermore, in step one, the optical resin is any ultraviolet optical resin that can be prepared by femtosecond laser two-photon polymerization, mainly including: epoxy resin SU-8, organic / inorganic hybrid photoresist IP-DIP, SZ2080, ultraviolet optical curing glue NOA61, NOA63, etc.; the substrate sheet is placed on a hot table for pre-heating, the drying temperature is 50-150°C, and the drying time is 5-30min; to avoid photoresist exposure failure, the photoresist dripping and heating process are carried out under a yellow light environment; the photoresist liquid collection tool is a rubber-tipped dropper, and the liquid collection dosage is 1 drop; a constant temperature heating table is used to heat the substrate sheet; the substrate sheet pre-baking heating temperature is 90-120°C, and the heating time is 90-120min; the substrate sheet size is 24*24*0.14mm; and it is naturally cooled at room temperature after pre-baking.

[0023] Furthermore, in step 2, the galvanometer-based femtosecond laser direct writing processing system includes a fiber femtosecond laser oscillator, an attenuation plate, an optical gate, a reflector, a beam expansion system, a scanning galvanometer, a 4F optical system and an oil-immersed objective lens; the femtosecond pulse laser generated by the femtosecond laser oscillator passes through the attenuation plate and the optical gate, passes through the reflector and then passes through the beam expansion system, the laser beam after beam expansion controls the beam deflection angle through the scanning galvanometer, and then the laser beam is projected to the entrance pupil of the objective lens by the 4F optical system, and the beam is focused into the processing sample through the oil-immersed objective lens, and combined with the movement of the displacement stage to achieve three-dimensional scanning; at the same time, a real-time monitoring system composed of an illumination light source, a filter, and an imaging CCD is used to observe the status of the sample during processing in real time;

[0024] The femtosecond laser center wavelength of the galvanometer-based femtosecond laser direct writing processing system is 780nm, the pulse width is 80-180fs, and the repetition frequency is 85-100MHz; the attenuation plate is a gradient density filter with an operating wavelength of 400-1100nm; the reflector is a dielectric film reflector with an operating wavelength of 800nm; the lens of the 4F optical system is a K9 glass plano-convex lens with a focal length of 100-300mm.

[0025] Furthermore, in step 3, the laser processing power is 15-30mw, and the single point exposure time is 200-1000μs; after the laser processing is completed, the substrate is removed, and then the side with the photoresist is placed obliquely in a beaker downward, and n-propanol is poured along the wall of the beaker to cover the photoresist for development; the photoresist development time is 10-90min; the wavelength of the ultraviolet lamp used for ultraviolet exposure is 300-450nm, the power of the ultraviolet lamp is 1-10W, and the exposure time is 5-60min. The above operations are all performed under yellow light environment;

[0026] In step three, a cavity is sealed on the substrate sheet and water is injected to place the compound eye lens 1 in a water environment, and then the microscopic observation system 3 is aligned with the compound eye lens 1 to complete the combination of the compound eye imaging system.

[0027] In a third aspect, the present invention also provides an application of a micro-artificial compound eye imaging system with a large depth of field in image detection in space, specifically using the micro-artificial compound eye imaging system to perform real-time observation of objects at different distances in space.

[0028] Compared with the prior art, the advantages of the present invention are as follows:

[0029] (1) The present invention provides a micro-artificial compound eye imaging system with a large depth of field, a preparation method and an application thereof, which solves the problem of limited depth of field of the curved surface artificial compound eye by specially designing the sub-eye function surface;

[0030] (2) Through femtosecond laser two-photon polymerization-assisted contour scanning, high-precision and rapid preparation of special surface-shaped micro-artificial compound eyes was achieved;

[0031] (3) Successfully combined the micro-curved artificial compound eye with the microscopic observation system to achieve the preparation of a micro-artificial compound eye imaging system with a large depth of field;

[0032] (4) The artificial compound eye imaging system and preparation method have the outstanding advantages of simple design, universal method, strong operability and wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0034] Figure 1 Schematic diagram of a micro-artificial compound eye imaging system with a large depth of field;

[0035] Figure 2 Schematic diagrams of the working principles of a conventional uniform curved compound eye lens (a) and a large depth of field curved compound eye lens (b) prepared by the present invention;

[0036] Figure 3 This is a schematic diagram of the optical path of the preparation of a micro artificial compound eye lens with a large depth of field - femtosecond laser two-photon polymerization assisted shell scanning processing of the present invention;

[0037] Figure 4 This is a scanning electron microscope characterization image of a large depth of field micro artificial compound eye lens 1 prepared according to the present invention;

[0038] Figure 5 A schematic diagram of a focusing test optical path of a large depth of field micro artificial compound eye lens 1 prepared according to the present invention;

[0039] Figure 6 The light spot energy distribution on two focusing planes of the large depth of field micro artificial compound eye lens 1 prepared by the present invention;

[0040] Wherein, a is the light spot energy distribution on the focusing plane of the small lens 9 in all sub-eyes; b is the light spot energy distribution on the focusing plane of the large lens 8 in all sub-eyes;

[0041] Figure 7 A schematic diagram of the test of the large depth of field micro-artificial compound eye imaging system prepared by the present invention;

[0042] Figure 8 This is a diagram of imaging two different space objects by the large depth of field micro artificial compound eye lens 1 prepared by the present invention;

[0043] Among them, a is the single imaging of the number "3" at a distance of 190 μm from the fly-eye lens, and b is the imaging of the letter "f" at a distance of 10 cm from the fly-eye lens;

[0044] Fig. 9 The large-depth-of-field micro-artificial compound eye imaging system prepared by the present invention directly collects images of two objects in different planes. DETAILED DESCRIPTION

[0045] In order to clearly and completely describe the technical solution and its specific working process of the present invention, the specific implementation methods of the present invention are as follows in conjunction with the accompanying drawings of the specification:

[0046] Example 1

[0047] The present invention designs a special functional surface shape of the sub-eyes, so that the focusing spots of the sub-eyes are distributed in two planes and the images are formed in one plane, which expands the imaging depth of the bionic artificial compound eye lens, thereby realizing the reception of the images of all sub-eyes at a certain plane position. The device uses femtosecond laser additive manufacturing assisted shell scanning technology to prepare a high-precision curved surface profile that meets the design, realizing image acquisition with a wide field of view and a large depth of field.

[0048] Specifically, a micro artificial compound eye imaging system with a large depth of field comprises a compound eye lens 1, an objective lens 2 and a microscopic observation system 3; wherein the objective lens 2 is located behind the compound eye lens 1 and aligned with the center line of the compound eye lens 1, and the microscopic observation system 3 is located behind the objective lens 2 to receive imaging information; the compound eye lens 1 comprises a spherical crown base 4, a central sub-eye 5, a first circle eye 6 and a second circle eye 7; the central sub-eye 5 is located at the vertex of the spherical crown base 4, and the first circle eye 6 and the second circle eye 7 surround the first circle and the second circle of the central sub-eye 5; wherein the central sub-eye 5, the first circle eye 6 and the second circle eye 7 are all composite lens structures composed of a large lens 8 and a small lens 9; the small lens 9 is located above the large lens 8; the central sub-eye 5, the first circle eye 6 and the second circle eye 7 are all located on the surface of the spherical crown base 4 and the center line angles of adjacent sub-eyes are The field of view of the fly-eye lens 1 is The focal lengths of the large lens 8 and the small lens 9 vary with the angles between the center lines of the sub-eyes where they are located and the center line of the central sub-eye 5 .

[0049] In this embodiment, the focal lengths of the large lenses 8 in the first circle eye 6 and the second circle eye 7 are L2 and L3 respectively, which are calculated by the following formula:

[0050]

[0051] Wherein, L1 is the focal length of the large lens 8 in the central sub-eye 5, R o is the radius of the sphere where the spherical cap base 4 is located, is the field of view of the fly-eye lens 1, It is the included angle between the center lines of adjacent sub-eyes.

[0052] The focal lengths of the small lenses 9 in the central sub-eye 5, the first circle eye 6 and the second circle eye 7 are l1, l2 and l3 respectively, which are calculated by the convex lens imaging formula:

[0053]

[0054] Among them, W min is the minimum object distance.

[0055] In this embodiment, L1 is 675.00-800.00 μm, and the viewing angle The range is 100°-110°; the minimum object distance is W min The range is 150-675μm.

[0056] Example 2

[0057] This embodiment provides a method for preparing a micro-artificial compound eye imaging system with a large depth of field, and the specific steps are as follows:

[0058] (1) Design of compound eye lens

[0059] Specific steps: First, design the central sub-eye 5, the first circle eye 6 and the second circle eye 7 to be evenly distributed on the spherical crown base 4. The radius and height of the spherical crown base 4 are 150μm and 75μm respectively; the radius of the central sub-eye 5, the first circle eye 6 and the second circle eye 7 are all 40μm. It is calculated that the radius of the arc distributed on the spherical crown base 4 is about 187.50μm, the angle between the sub-eyes is about 21.25°, and the field of view of the entire compound eye lens 1 is about 106.25°. In this embodiment, the compound eye works in a water environment with a refractive index of 1.33. In addition, the experimental resin of the compound eye lens 1 is a new type of organic-inorganic hybrid polymer SZ-2080, and the refractive index of the resin is 1.5, so the refractive index difference is 0.17. The focal length of the large lens 8 of the central sub-eye 5 is set to 675.00μm. The focal lengths of the large lenses 8 in the first circle eye 6 and the second circle eye 7 can be calculated by the angle between the sub-eyes, and the calculated values ​​are 710.56μm and 848.71μm. Since the thickness of the substrate sheet is about 140μm, the height of the compound eye lens 1 is about 90μm, and the object distance of the near object after the cavity is sealed is about 190μm, it can be known from the convex lens imaging formula that the focal lengths of the small lenses 9 of the central sub-eye 5, the first circle eye 6, and the second circle eye 7 are set to 150.00μm, 151.69μm, and 157.15μm, respectively. The spherical centers of the large lenses 8 and the small lenses 9 of the central sub-eye 5, the first circle eye 6, and the second circle eye 7 are respectively on the center lines of their respective sub-eyes, and the distances between the spherical centers are 97.17μm, 102.85μm, and 125.18μm, respectively. The curvature radii of the large lens 8 of the central sub-eye 5, the first circle eye 6 and the second circle eye 7 are calculated from the relationship formula of lens focal length and curvature to be approximately 114.75 μm, 120.80 μm and 144.28 μm respectively. The curvature radii of the small lens 9 of the central sub-eye 5, the first circle eye 6 and the second circle eye 7 are approximately 25.50 μm, 25.79 μm and 26.72 μm respectively.

[0060] After determining the focal length design of the compound eye lens 1, the height distribution of the lens at different positions can be obtained according to the functional surface equation of the spherical lens. Then, the height information of the surface contour of the compound eye lens 1 can be calculated according to the height and radius of the spherical crown base 1. Through C++ programming, a program is written to output the surface contour information of the device as three-dimensional point cloud data, and export it to the Txt text in the data format of (x, y, z, l), where x, y, z are position information, and l is the light gate switch (0 represents the light gate closed, and 1 represents the light gate open). This embodiment uses a contour scanning processing method to make the compound eye. Taking the outer contour of the compound eye as a reference, the shell layer with a shell thickness of 2μm is expanded inward, and the point cloud data of the micro compound eye lens 1 is generated into the file to be processed.

[0061] (2) Sample preparation and system leveling;

[0062] Specific steps: First, prepare the substrate sheet in advance, and clean the substrate sheet ultrasonically in an ultrasonic machine for 10 minutes to remove large debris and dust particles on the surface. Wipe the substrate sheet with a cotton ball soaked in anhydrous ethanol, then rinse its surface with deionized water to remove residual ethanol, and dry it in a vacuum drying oven at 70° for 5 minutes; use a rubber-tipped dropper to draw a drop of optical resin SZ2080 and drop it on the surface of the substrate sheet; place the substrate sheet on a heating table for pre-baking at a temperature of 100° and a pre-baking time of 90 minutes, and cool it at room temperature after pre-baking.

[0063] Next, use Figure 3 The galvanometer-based femtosecond laser direct writing processing system shown in the figure performs the operation of preparing the compound eye lens 1 by femtosecond laser direct writing. Specifically, the cooled substrate sheet is placed on the stage of the galvanometer-based femtosecond laser direct writing processing system. The femtosecond pulse laser (central wavelength of 800nm, pulse width of 100fs, repetition frequency of 80MHz) generated by the femtosecond laser oscillator passes through the attenuation plate and the optical gate in sequence, and then passes through the reflector and the beam expansion system, so that the laser beam after the beam size is expanded five times uses the scanning galvanometer to control its deflection angle, and then the 4F optical system deflects the angle of the laser beam and projects it to the entrance pupil of the objective lens. The oil-immersed objective lens with a numerical aperture of 1.35 and a magnification of 60 times produced by Olybus Company focuses the incident light tightly inside the processed sample, thereby achieving three-dimensional scanning processing. At the same time, the real-time monitoring system composed of the illumination light source, the filter and the CCD can observe the state of the sample during processing in real time. The illumination light source uses a white LED light source; the filter uses a band-selective absorption filter with a transmission range of 580-2300nm; the real-time observation system CCD is a domestic high-definition driver-free industrial camera. Before the formal processing begins, the laser energy is adjusted to the reference value, and the laser is focused on the interface between the polymer film and the substrate. By turning the support screws of the stage in the system, the spot energy remains unchanged when moving 500μm left and right or up and down. At this time, it can be determined that the stage has been leveled.

[0064] (3) Preparation of micro artificial compound eyes with large depth of field;

[0065] The specific steps are as follows: Open the point cloud file of the compound eye lens 1 generated in step (2). Adjust the position of the attenuation plate so that the laser power measured in front of the objective lens reaches 23.0 mW. Finally, set the single point exposure time to 100 μs on the processing software, click the start button, and start point-by-point scanning processing.

[0066] Then the device is developed and dried: the processed substrate is placed in the photoresist developer n-propanol and immersed in the developer for 60 minutes. After the development is completed, the substrate is taken out of the developer and dried naturally.

[0067] Finally, the device is post-processed: the dried compound eye lens 1 is placed under a high-power UV lamp for 5 minutes, with a UV lamp power of 1W, so that the resin in the unexposed part except the scanning shell layer during the femtosecond laser direct writing process is polymerized to improve the long-term stability of the structure. Finally, a micro-curved artificial compound eye lens 1 with a large depth of field is prepared.

[0068] like Figure 1 It can be seen that the schematic diagram of the micro-artificial compound eye imaging system with a large depth of field;

[0069] The designed compound eye lens 1 with a large depth of field is composed of a central sub-eye 5, a first circle eye 6 and a second circle eye 7; each sub-eye is a composite structure composed of two lenses with different curvature radii, namely a large lens 8 and a small lens 9; wherein the focal lengths of the large lens 8 and the small lens 9 are different according to the position of the sub-eye;

[0070] like Figure 2 As shown in (a), the structure of the traditional uniform curved compound eye lens is shown in the figure. The distant trees and the nearby butterflies are imaged in two curved planes, and it is impossible to receive the images of the two objects on the same plane. Figure 2 As shown in (b), the large depth of field curved fly-eye lens designed in this embodiment has a special surface-shaped sub-eye, so that the small lens 9 detects relatively close objects, the large lens 8 detects distant objects, and the images of the two lenses are in the same plane;

[0071] like Figure 3 It can be seen that the optical path schematic diagram of femtosecond laser two-photon polymerization assisted shell scanning processing;

[0072] Among them, the femtosecond pulse laser generated by the femtosecond laser oscillator passes through the attenuation plate and the light gate, and then passes through the beam expansion system through the reflector. The laser beam after the light beam is expanded by 5 times controls the beam deflection angle through the scanning galvanometer, and then the laser beam is projected to the entrance pupil of the objective lens by the 4F optical system. The light beam is focused into the processed sample through the oil-immersed objective lens and combined with the movement of the translation stage to achieve three-dimensional scanning.

[0073] like Figure 4 , is a scanning electron microscope photograph of the large depth of field micro artificial compound eye lens 1 prepared in this embodiment;

[0074] Among them, the large depth of field compound eye lens 1 has a complete shape and contour, and the central sub-eye 5, the first circle eye 6 and the second circle eye 7 have clear contours; the large lens 8 and the small lens 9 of each sub-eye have good preparation effects and high fidelity with the expected design;

[0075] like Figure 5 It can be seen that the focusing test optical path of the large depth of field micro artificial compound eye lens 1 prepared in this embodiment;

[0076] The laser source passes through the fly-eye lens 1 and enters the CCD through the objective lens 2.

[0077] like Figure 6 It can be seen that the energy distribution diagram of the light spot in the two focusing planes of the micro artificial compound eye lens 1 with a large depth of field;

[0078] Among them, by adjusting the relative positions of the objective lens 2, the CCD and the compound eye lens 1, the focused light field energy distribution of the two focal planes is captured, indicating that the sub-eyes of the large depth of field micro artificial compound eye lens 1 prepared in this embodiment can focus the light spot into two planes;

[0079] Example 3

[0080] By designing a special functional surface shape of the sub-eye, the problem of limited depth of field of traditional artificial compound eye imaging is solved, and the imaging of near and far objects is simultaneously received on the same plane. The artificial compound eye lens 1 prepared by femtosecond laser additive manufacturing assisted shell scanning technology can achieve large depth of field imaging. Finally, combined with the microscopic observation system 3, a large depth of field micro-bionic artificial compound eye imaging system is obtained.

[0081] This embodiment adopts a method for preparing a micro artificial compound eye imaging system with a large depth of field, and the specific steps are as follows:

[0082] Steps (1), (2) and (3) are the same as those in Example 1.

[0083] (4) Preparation of a micro-artificial compound eye imaging system with a large depth of field;

[0084] Specific steps: After completing the preparation of the compound eye lens 1 by femtosecond laser additive manufacturing, a substrate sheet with a thickness of about 140 μm is placed on the edge of the compound eye lens 1 to separate the compound eye from the upper substrate sheet to form a cavity, and deionized water is injected into the cavity to place the compound eye lens 1 in a water environment; then the cavity is placed on a microscope stage to achieve the preparation of a micro-artificial compound eye imaging system with a large depth of field through focusing and alignment.

[0085] (5) Image acquisition;

[0086] Specific steps: Place two different masks in different spaces under the bionic artificial compound eye lens 1, which are the letter "f" 10 cm away from the compound eye lens and the number "3" 190 μm away from the compound eye lens. Use an illumination light source to illuminate the target object, and then use the combined compound eye imaging system to directly capture the image of the target object.

[0087] like Figure 7 It can be seen that the imaging system test schematic diagram of the large depth of field micro artificial compound eye prepared in this embodiment;

[0088] The imaging system consists of a compound eye lens 1, an objective lens 2 and a microscopic observation system 3. The objective lens 2 is a 20x objective lens, and the microscopic observation system 3 consists of a domestic high-definition CCD and a computer. At the same time, the image can be observed on the computer by irradiating the mask with a light source.

[0089] like Figure 8 It can be seen that the micro artificial compound eye imaging system with large depth of field can image near and far objects;

[0090] The left picture shows the single imaging of the number "3" 190 μm away from the compound eye lens by the large depth of field micro artificial compound eye lens 1 prepared by the present invention, and the right picture shows the imaging result of the letter "f" 10 cm away from the compound eye lens by the compound eye lens 1.

[0091] like Fig. 9 It can be seen that the imaging results of different space objects by the large depth of field micro-artificial compound eye imaging system;

[0092] The conventional uniform compound eye lens cannot simultaneously receive images of objects at different distances on the same plane; the large depth of field micro-artificial compound eye imaging system prepared by the present invention can simultaneously capture images of two objects on different planes.

[0093] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0094] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0095] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A micro artificial compound eye imaging system with a large depth of field, characterized in that: The invention comprises a compound eye lens (1), an objective lens (2) and a microscopic observation system (3); wherein the objective lens (2) is located behind the compound eye lens (1) and aligned with the center line of the compound eye lens (1); and the microscopic observation system (3) is located behind the objective lens (2) to receive imaging information; the compound eye lens (1) comprises a spherical crown base (4), a central sub-eye (5), a first circle eye (6) and a second circle eye (7); the central sub-eye (5) is located at the top of the spherical crown base (4); the first circle eye (6) and the second circle eye (7) surround the first circle and the second circle of the central sub-eye (5); wherein the central sub-eye (5), the first circle eye (6) and the second circle eye (7) are all composite lens structures composed of a large lens (8) and a small lens (9); the small lens (9) is located on the large lens (8); the central sub-eye (5), the first circle eye (6) and the second circle eye (7) are all located on the surface of the spherical crown base (4) and the included angles of the center lines of adjacent sub-eyes are The field of view of the compound eye lens (1) is The focal lengths of the large lens (8) and the small lens (9) vary with the angles between the center lines of the sub-eyes where they are located and the center line of the central sub-eye (5).

2. A micro artificial compound eye imaging system with a large depth of field as claimed in claim 1, characterized in that: The focal lengths of the large lenses (8) in the first circle eye (6) and the second circle eye (7) are L2 and L3 respectively, which are calculated by the following formula: Wherein, L1 is the focal length of the large lens (8) in the central sub-eye (5), R o is the radius of the sphere on which the spherical cap base (4) is located, is the field of view of the fly-eye lens (1), It is the included angle between the center lines of adjacent sub-eyes.

3. The micro-artificial compound eye imaging system with a large depth of field as claimed in claim 1, characterized in that: The focal lengths of the small lenses (9) in the central sub-eye (5), the first circle eye (6) and the second circle eye (7) are l1, l2 and l3 respectively, which are calculated by the convex lens imaging formula: Among them, W min is the minimum object distance.

4. A micro artificial compound eye imaging system with a large depth of field as claimed in claim 2 or 3, characterized in that: L1 is 675.00-800.00μm, field of view The range is 100°-110°; the minimum object distance is W min The range is 150-675μm.

5. The micro-artificial compound eye imaging system with large depth of field as claimed in claim 1, characterized in that: The central sub-eye (5), the first circle eye (6) and the second circle eye (7) are closely arranged on the spherical cap base (4); the radius of the central sub-eye (5) is The spherical centers of the large lens (8) and the small lens (9) of the central sub-eye (5), the first circle eye (6) and the second circle eye (7) are respectively on the center line of each sub-eye and the distance between the spherical centers ranges from 90 to 130 μm.

6. The method for preparing a micro-artificial compound eye imaging system with a large depth of field as claimed in claim 1, characterized in that: The specific steps are as follows: (1) Sample preparation; The specific steps are as follows: first, drop the optical resin on the substrate; place the substrate on a hot table for preheating, and then cool it naturally at room temperature; (2) Leveling processing system; Specific steps: Place the prepared substrate in the galvanometer-based femtosecond laser direct writing processing system, adjust the laser energy to the reference value, focus the laser on the interface between the polymer film formed after pre-baking the optical resin and the substrate, rotate the stage support screws so that the spot energy remains unchanged when moving left and right and forward and backward, and the stage is considered to be leveled at this time; then, control the laser to focus on the interface between the optical resin and the substrate and make the focus go deep into the substrate; (3) Preparation of micro-artificial compound eyes with large depth of field and integration of imaging systems; The specific steps are as follows: generating point cloud data of the designed micro compound eye lens (1) into a file to be processed; The laser processing power is set and point-by-point scanning processing is performed; the scanned substrate is developed, dried and exposed to ultraviolet light, and finally a micro-curved artificial compound eye lens (1) with a large depth of field is prepared; finally, the compound eye lens (1) is sealed and aligned with the microscopic observation system (3) to complete the integration of the imaging system.

7. The method for preparing a micro-artificial compound eye imaging system with a large depth of field as claimed in claim 6, characterized in that: In step 1, the optical resin is a variety of ultraviolet optical resins that can be prepared by femtosecond laser two-photon polymerization, including: epoxy resin SU-8, organic / inorganic hybrid photoresist IP-DIP, SZ2080, ultraviolet optical curing glue NOA61, NOA63; the substrate is placed on a hot table for pre-heating, the drying temperature is 50-150°C, and the drying time is 5-30min; to avoid photoresist exposure failure, the photoresist dripping and heating process are all carried out under a yellow light environment; the photoresist liquid collection tool is a rubber-tipped dropper, and the liquid collection dosage is 1 drop; a constant temperature heating table is used to heat the substrate; the substrate pre-baking heating temperature is 90-120°C, and the heating time is 90-120min; the substrate size is 24*24*0.14mm; and it is naturally cooled at room temperature after pre-baking.

8. The method for preparing a micro-artificial compound eye imaging system with a large depth of field as claimed in claim 6, characterized in that: In step 2, the galvanometer-based femtosecond laser direct writing processing system includes a fiber femtosecond laser oscillator, an attenuation plate, an optical gate, a reflector, a beam expansion system, a scanning galvanometer, a 4F optical system and an oil-immersed objective lens; the femtosecond pulse laser generated by the femtosecond laser oscillator passes through the attenuation plate and the optical gate, passes through the reflector and then passes through the beam expansion system, the laser beam after beam expansion controls the beam deflection angle through the scanning galvanometer, and then the laser beam is projected to the entrance pupil of the objective lens by the 4F optical system, and the beam is focused into the processing sample through the oil-immersed objective lens, and combined with the movement of the displacement stage to achieve three-dimensional scanning; at the same time, a real-time monitoring system composed of an illumination light source, a filter, and an imaging CCD is used to observe the status of the sample during processing in real time; The femtosecond laser center wavelength of the galvanometer-based femtosecond laser direct writing processing system is 780nm, the pulse width is 80-180fs, and the repetition frequency is 85-100MHz; the attenuation plate is a gradient density filter with an operating wavelength of 400-1100nm; the reflector is a dielectric film reflector with an operating wavelength of 800nm; the lens of the 4F optical system is a K9 glass plano-convex lens with a focal length of 100-300mm.

9. The method for preparing a micro-artificial compound eye imaging system with a large depth of field as claimed in claim 6, characterized in that: In step 3, the laser processing power is 15-30mw, and the single point exposure time is 200-1000μs; after the laser processing is completed, the substrate is removed, and then the side with the photoresist is placed obliquely in a beaker downward, and n-propanol is poured along the wall of the beaker to cover the photoresist for development; the photoresist development time is 10-90min; the wavelength of the ultraviolet lamp used for ultraviolet exposure is 300-450nm, the power of the ultraviolet lamp is 1-10W, and the exposure time is 5-60min. The above operations are all carried out under yellow light environment; In step three, a cavity is sealed on the substrate sheet and water is injected to place the compound eye lens 1 in a water environment, and then the microscopic observation system 3 is aligned with the compound eye lens 1 to complete the combination of the compound eye imaging system.

10. The application of a micro-artificial compound eye imaging system with a large depth of field in space image detection as claimed in claim 1, characterized in that: Specifically, the micro-artificial compound eye imaging system is used to perform real-time observation of objects at different distances in space.

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