Camera lens device based on wavefront coding

Abstract

The utility model provides a camera lens device based on wavefront coding, and belongs to the technical field of optical detection. The camera lens device based on wavefront coding comprises a lens barrel and an industrial camera, the rear end of the lens barrel is connected with the industrial camera, an original infrared lens is installed in the lens barrel, a phase plate is fixed at the front end of the lens barrel, and a diaphragm is arranged between the phase plate and the original infrared lens. A phase plate is added, and the depth of field of the camera is expanded by using an encoding-decoding method, so that the measurement precision of the infrared deflection technology is improved; a wavefront coding method is adopted, so that the system is insensitive to defocus, and coding is realized by adding a phase plate into a camera lens; the phase plate is added, and the depth of field of the lens is expanded, so that in infrared deflection measurement, the camera can clearly image the measured lens and the light source, the position resolution and the angle resolution are improved, and the surface type reconstruction precision is improved.

Description

A camera lens device based on wavefront coding Technical Field

[0001] This application relates to the field of optical inspection, and more specifically, to a camera lens device based on wavefront coding. Background Technology

[0002] Currently, during the grinding stage of optical processing, large-aperture optical mirrors exhibit high surface roughness, resulting in diffuse reflection of visible light. Therefore, interferometers cannot be used for high-precision inspection, and contact-based coordinate measuring machines (CMMs) are time-consuming and inaccurate. Infrared deflection technology can be employed to inspect the mirror's surface shape. Infrared deflection technology offers advantages such as high measurement accuracy, a large dynamic range, and fast measurement speed.

[0003] The existing technical solutions mentioned above have the following drawbacks: Due to the limitation of the measurement depth of field, the infrared camera cannot focus on the light source and the surface of the mirror being measured at the same time. Generally, the camera is focused on the mirror to improve the position resolution of the mirror. At this time, the light source is in a defocused state, the fringes are not clear, which leads to a reduction in angular resolution and seriously affects the surface shape measurement accuracy and the stability of the measurement system. Summary of the Invention

[0004] To overcome the above shortcomings, this application provides a camera lens device based on wavefront coding, which aims to improve the problem that the angular resolution is reduced due to the light source being out of focus, thus affecting the accuracy of surface shape measurement and the measurement system.

[0005] This application provides a camera lens device based on wavefront coding, including a lens barrel and an industrial camera. The rear end of the lens barrel is connected to the industrial camera. A native infrared lens is installed inside the lens barrel. A phase plate is fixed to the front end of the lens barrel. An aperture is provided between the phase plate and the native infrared lens.

[0006] In a preferred embodiment of this utility model, the outer surface of the lens barrel is provided with an external thread, and the industrial camera is provided with an internal thread. The external thread and the internal thread are engaged for threaded connection. The external thread of the lens barrel is a standardized interface thread to meet the requirements of various camera interfaces. The positional tolerance of the interface screw hole is ≤0.02mm to ensure the coaxiality of the optical system and the camera.

[0007] In a preferred embodiment of this invention, the aperture stop is attached to the back of the phase plate and is fixed by a pressure ring. The original infrared lens adopts a floating lens assembly structure, and the lens assembly is connected to the lens barrel by four symmetrically distributed flexible hinges. The torsional stiffness of the flexible hinges is ≥100 N·m / rad, which can compensate for radial stress deformation during lens assembly.

[0008] In a preferred embodiment of this utility model, the lens barrel adopts a split sleeve structure, including a front lens barrel and a rear lens barrel. The front lens barrel and the rear lens barrel are slidably connected by a precision dovetail guide rail, and the guide rail is provided with a displacement scale with a scale value of 0.01mm. With the help of the locking screw, the axial distance between the phase plate and the original infrared lens can be precisely adjusted.

[0009] In a preferred embodiment of this invention, the aperture is connected to the inner wall of the lens barrel via a cantilever beam structure. The cantilever beam is made of beryllium bronze and is an elastic cantilever. The coaxiality error between the central axis of the aperture and the optical axis of the original infrared lens is ≤0.005mm to ensure beam symmetry. The split-type sleeve guide rail and the elastic cantilever beam aperture structure enable the infrared lens to have precise axial and radial adjustment capabilities, solving the problem of optical path alignment between the phase plate and the lens.

[0010] In a preferred embodiment of this utility model, the edge of the phase plate is provided with at least three circumferentially evenly distributed positioning bosses, and the inner wall of the front end of the lens barrel is provided with a T-shaped groove that mates with the positioning bosses. An elastic rubber pad is provided between the positioning bosses and the T-shaped groove to eliminate circumferential stress deformation during threaded connection.

[0011] In a preferred embodiment of this utility model, the inner wall of the lens barrel is provided with a spiral-shaped matte groove, the depth of the matte groove is 2-3mm, and the surface of the groove wall is sprayed with a black matte light-absorbing coating with a reflectivity ≤0.5% to suppress internal stray light reflection.

[0012] In a preferred embodiment of this invention, a detachable filter holder is provided between the phase plate and the aperture stop. The filter holder uses a magnetic interface, allowing for quick replacement of narrow-bandpass filters with a passband width ≤10nm to adapt to infrared light sources of different wavelengths. The use of a magnetic filter holder and a standardized camera interface provides the device with compatibility across light source wavelengths and camera models, expanding the application scenarios of the mechanical structure.

[0013] In a preferred embodiment of this invention, a shock-absorbing flange is provided at the rear end of the lens barrel. Multiple sets of annular springs are embedded inside the shock-absorbing flange, with a spring stiffness coefficient of 5-10 N / mm, capable of attenuating vibrations in the frequency range of 20-2000 Hz, suitable for anti-interference requirements in use. The anti-interference design of the spiral extinction groove and the shock-absorbing flange structure is specifically optimized for stray light, vibration, and other interference sources in industrial environments, significantly improving detection stability.

[0014] Beneficial Effects: This application provides a camera lens device based on wavefront coding, which optimizes the optical lens of the infrared deflection device by adding a phase plate and using an encoding-decoding method to extend the depth of field of the camera, thereby improving the measurement accuracy of infrared deflection. The wavefront coding method makes the system insensitive to defocusing. Encoding is achieved by adding a phase plate inside the camera lens, and the acquired image information is then decoded, thus extending the depth of field and improving the measurement accuracy of infrared deflection. Adding a phase plate extends the depth of field of the lens, enabling the camera to clearly image both the measured mirror and the light source during infrared deflection measurements, improving positional and angular resolution, and thus improving the accuracy of surface reconstruction. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 is a three-dimensional structural diagram of a camera lens device based on wavefront coding provided in an embodiment of this application;

[0017] Figure 2 is a schematic diagram of the three-dimensional structure of the lens barrel provided in the embodiment of this application;

[0018] Figure 3 is a partial cross-sectional structural diagram provided in the embodiments of this application.

[0019] In the diagram: 1. Phase plate; 2. Aperture; 3. Lens barrel; 31. Front lens barrel; 32. Rear lens barrel; 33. Extinction groove; 34. Vibration damping flange; 4. Original infrared lens; 5. Industrial camera; 6. Filter holder. Detailed Implementation

[0020] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0021] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0022] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0023] Please refer to Figures 1-3. This utility model provides a camera lens device based on wavefront coding, including a lens barrel 3 and an industrial camera 5. The rear end of the lens barrel 3 is connected to the industrial camera 5. A native infrared lens 4 is installed inside the lens barrel 3. A phase plate 1 is fixed to the front end of the lens barrel 3. An aperture 2 is provided between the phase plate 1 and the native infrared lens 4.

[0024] In a specific embodiment of this utility model, the outer surface of the lens barrel 3 is provided with an external thread, and the industrial camera 5 is provided with an internal thread. The external thread and the internal thread are threaded together. The external thread of the lens barrel 3 is a standardized interface thread, which can meet the requirements of various camera interfaces. The position tolerance of the interface screw hole is ≤0.02mm, ensuring the coaxiality of the optical system and the camera.

[0025] In a specific embodiment of this utility model, the aperture stop 2 is attached to the back of the phase plate 1 and is fixed by a pressure ring. The original infrared lens 4 adopts a floating lens group structure, and the lens group is connected to the lens barrel 3 by four symmetrically distributed flexible hinges. The torsional stiffness of the flexible hinges is ≥100 N·m / rad, which can compensate for radial stress deformation during lens assembly.

[0026] In a specific embodiment of this utility model, the lens barrel 3 adopts a split sleeve structure, including a front lens barrel 31 and a rear lens barrel 32. The front lens barrel 31 and the rear lens barrel 32 are slidably connected by a precision dovetail guide rail, and the guide rail is provided with a displacement scale with a scale value of 0.01mm. With the help of the locking screw, the axial distance between the phase plate 1 and the original infrared lens 4 can be precisely adjusted.

[0027] In a specific embodiment of this utility model, the aperture 2 is connected to the inner wall of the lens barrel 3 via a cantilever beam structure. The cantilever beam is made of beryllium bronze and is an elastic cantilever. The coaxiality error between the central axis of the aperture 2 and the optical axis of the original infrared lens 4 is ≤0.005mm to ensure beam symmetry. The split-type sleeve guide rail and the elastic cantilever beam aperture 2 structure enable the infrared lens to have precise axial and radial adjustment capabilities, solving the problem of optical path alignment between the phase plate 1 and the lens.

[0028] In a specific embodiment of this utility model, the edge of the phase plate 1 is provided with at least three circumferentially evenly distributed positioning bosses, and the inner wall of the front end of the lens barrel 3 is provided with a T-shaped groove that cooperates with the positioning bosses. An elastic rubber pad is provided between the positioning bosses and the T-shaped groove to eliminate circumferential stress deformation during threaded connection.

[0029] In a specific embodiment of this utility model, a spiral-shaped light-absorbing groove 33 is provided on the inner wall of the lens barrel 3. The depth of the light-absorbing groove 33 is 2-3mm. The surface of the groove wall of the light-absorbing groove 33 is sprayed with a black matte light-absorbing coating with a reflectivity of ≤0.5% to suppress internal stray light reflection.

[0030] In a specific embodiment of this utility model, a detachable filter holder 6 is provided between the phase plate 1 and the aperture 2. The filter holder 6 adopts a magnetic interface, which allows for quick replacement of narrow-bandpass filters with a passband width ≤10nm to adapt to infrared light sources of different wavelengths. The use of the magnetic filter holder 6 and a standardized camera interface gives the device compatibility across light source wavelengths and camera models, expanding the application scenarios of the mechanical structure.

[0031] In a specific embodiment of this utility model, a shock-absorbing flange 34 is provided at the rear end of the lens barrel 3. Multiple sets of annular springs are embedded inside the shock-absorbing flange 34, with a spring stiffness coefficient of 5-10 N / mm, which can attenuate vibrations in the frequency range of 20-2000 Hz, suitable for anti-interference requirements in use. The anti-interference design of the spiral extinction groove 33 and the shock-absorbing flange 34 structure is specifically optimized for stray light, vibration, and other interference sources in industrial environments, significantly improving detection stability.

[0032] The working principle of this wavefront-coded camera lens device is as follows: During use, a phase plate 1 with known parameters is added near the lens aperture 2 to change the wavefront of the imaging camera, generating a certain optical path difference in the optical path. This blunts the entire optical system, making it insensitive to defocusing. The imaging beam is no longer focused on the focal plane, but forms a thin beam at the focal plane. This allows the point spread function and optical transfer function of the optical system to remain consistent over a larger depth of field. Traditional optical systems have point spread functions of different diameters at different depths of field, while the point spread function of wavefront-coded systems is an approximately isosceles triangle. The acquired image is a series of similarly blurred coded images. By using the same filter through a decoding algorithm, the blurred images can be restored, ultimately obtaining clear images at different depths of field. This achieves the purpose of expanding the depth of field of the camera lens, realizing infrared refraction measurement, and improving the accuracy of infrared refraction surface shape measurement.

[0033] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

Claims

1. A camera lens device based on wavefront coding, characterized in that, It includes a lens barrel (3) and an industrial camera (5). The rear end of the lens barrel (3) is connected to the industrial camera (5). A native infrared lens (4) is installed inside the lens barrel (3). A phase plate (1) is fixed at the front end of the lens barrel (3). An aperture (2) is provided between the phase plate (1) and the native infrared lens (4).

2. The camera lens device based on wavefront coding according to claim 1, characterized in that, The outer surface of the lens barrel (3) is provided with an external thread, and the industrial camera (5) is provided with an internal thread. The external thread and the internal thread are connected in a threaded manner. The external thread of the lens barrel (3) is a standardized interface.

3. A camera lens device based on wavefront coding according to claim 1, characterized in that, The aperture (2) is attached to the back of the phase plate (1). The aperture (2) is fixed by a pressure ring. The original infrared lens (4) adopts a floating lens group structure. The lens group is connected to the lens barrel (3) by four symmetrically distributed flexible hinges.

4. A camera lens device based on wavefront coding according to claim 1, characterized in that, The lens tube (3) adopts a split sleeve structure, including a front lens tube (31) and a rear lens tube (32). The front lens tube (31) and the rear lens tube (32) are slidably connected by a precision dovetail guide rail, and a displacement scale is provided on the guide rail.

5. A camera lens device based on wavefront coding according to claim 1, characterized in that, The edge of the phase plate (1) is provided with at least three circumferentially evenly distributed positioning bosses, and the inner wall of the front end of the lens barrel (3) is provided with a T-shaped groove that cooperates with the positioning bosses.

6. A camera lens device based on wavefront coding according to claim 1, characterized in that, The inner wall of the lens tube (3) is provided with a spiral matte groove (33), and the surface of the groove wall is coated with a black matte light-absorbing coating.

7. A camera lens device based on wavefront coding according to claim 1, characterized in that, A detachable filter holder (6) is provided between the phase plate (1) and the aperture (2), and the filter holder (6) adopts a magnetic interface.

8. A camera lens device based on wavefront coding according to claim 1, characterized in that, The rear end of the lens tube (3) is provided with a shock-absorbing flange (34), and multiple sets of annular springs are embedded inside the shock-absorbing flange (34).

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