Double telecentric ultraviolet security monitoring lens

Abstract

The invention discloses a double-telecentric ultraviolet security monitoring lens, and relates to the technical field of optical lenses. A dustproof and waterproof window, a front lens group, a beam splitter prism, an aperture diaphragm, a rear lens group and an imaging surface are sequentially arranged from an object side to an image side along an optical axis. The lens adopts a double-telecentric structure, the telecentricity of the object side and the telecentricity of the image side are both smaller than or equal to 0.2 degree, parallel light paths are arranged between the front lens group and the rear lens group, and the light parallelism is smaller than or equal to 0.1 degree. The dustproof and waterproof window is made of a sapphire material and plated with a hydrophobic antifouling film, and the lens is made of a fused quartz material and plated with an ultraviolet antireflection film. The imaging size stability is ensured through a double telecentric optical structure, a light splitting element can be conveniently inserted through a parallel light path to achieve real-time monitoring of ultraviolet light beams, the lens has the IP67 protection level through the protection design, the transmittance of the 300-400 nm waveband is improved to 85% or above through the ultraviolet antireflection film, and the imaging quality is improved. The method is suitable for outdoor ultraviolet security and protection monitoring, high-voltage circuit arc detection and camouflage target identification scenes.

Description

Technical Field

[0001] This application relates to a dual telecentric ultraviolet security monitoring lens, belonging to the field of optical lens technology. Background Technology

[0002] In the field of security monitoring, ultraviolet (UV) imaging technology, due to its sensitivity to specific wavelengths of light, is widely used in special scenarios such as high-voltage circuit arc detection and camouflaged target identification. As the core optical component of a UV imaging system, the performance of the UV monitoring lens directly affects image quality and detection accuracy. Currently, the UV security monitoring lenses commonly used in the industry are mainly of ordinary telecentric or non-telecentric structures, which have a certain application foundation in industrial inspection and scientific research. Meanwhile, the dual telecentric optical structure, as a high-precision imaging solution, has been applied in fields with high requirements for imaging stability, such as industrial lithography, precision measurement, and 3D printing. By maintaining telecentricity on both the object and image sides, it can effectively reduce magnification fluctuations caused by changes in object distance.

[0003] However, the current problem is that existing ultraviolet security surveillance lenses lack sufficient telecentricity control precision, making it difficult to meet the imaging stability requirements of large-scale outdoor monitoring. Furthermore, their narrow field of view and limited distortion correction capabilities result in image quality being easily affected in complex environments. In addition, existing dual-telecentric ultraviolet lenses are primarily designed for industrial indoor environments, resulting in complex structures, large sizes, and high manufacturing costs. They also lack protective designs for harsh outdoor environments, lacking dustproof and waterproof capabilities, making them unsuitable for outdoor security surveillance scenarios.

[0004] Meanwhile, existing technical solutions have limitations in the selection of optical materials and coating processes in the ultraviolet band. The ultraviolet transmittance is low, which affects the detection sensitivity and signal capture capability. They cannot effectively meet the comprehensive requirements of high imaging quality and environmental adaptability for security monitoring applications such as high-voltage circuit arc detection and camouflaged target identification. Summary of the Invention

[0005] The technical problem to be solved by this application is that the telecentricity control accuracy of existing ultraviolet security monitoring lenses is insufficient, making it difficult to meet the requirements of imaging stability for large-scale outdoor monitoring. In addition, the field of view is small and the distortion correction capability is limited, which makes the image quality easily affected in complex environments. At the same time, existing dual telecentric ultraviolet lenses lack protective design for harsh outdoor environments, do not have dustproof and waterproof functions, and have low ultraviolet transmittance, which affects detection sensitivity and signal capture capability.

[0006] To achieve the above objectives, this application provides the following technical solution: This application provides a dual telecentric ultraviolet security monitoring lens, which is provided with a dustproof and waterproof window, a front lens group, a beam splitter, an aperture stop, a rear lens group and an imaging surface arranged sequentially from the object side to the image side along the optical axis; The lens adopts a double telecentric structure, with both the object-side and image-side telecentricity ≤0.2°; the front lens group and the rear lens group are connected by a parallel optical path, and the parallelism of the light rays in the parallel optical path is ≤0.1°.

[0007] Optionally, the front lens group includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object side to the image side; The first lens is a negative optical power biconcave spherical lens, the second lens is a negative optical power crescent moon lens, the third lens is a positive optical power biconvex spherical lens, and the fourth lens is a positive optical power crescent moon lens.

[0008] Optionally, the rear lens group includes a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially from the object side to the image side; The fifth lens is a positive optical power biconvex spherical lens, the sixth lens is a negative optical power biconcave spherical lens, the seventh lens is a positive optical power biconvex spherical lens, and the eighth lens is a negative optical power crescent moon lens. Preferably, the refractive index of the first to eighth lenses is Nd=1.45-1.48 and the dispersion coefficient is Vd=65-70.

[0009] Optionally, the dustproof and waterproof window is made of sapphire material and coated with a hydrophobic and anti-fouling film. The first to the eighth lenses are all made of fused silica material and are all coated with an ultraviolet anti-reflection film. Preferably, the ultraviolet antireflective film has a wavelength range of 300nm-400nm and a transmittance of ≥85%; Preferably, the thickness of the dustproof and waterproof window is 3mm-5mm, the refractive index is Nd=1.75-1.80, and the dispersion coefficient is Vd=75-80.

[0010] Optionally, the beam splitter is disposed between the front lens group and the aperture stop for monitoring the ultraviolet beam and capturing abnormal signals; Preferably, the aperture stop has an aperture of 3mm-5mm and is located between the beam splitter and the rear lens group.

[0011] Optionally, the lens has an effective field of view on the object side ≥60mm, an effective field of view on the image side ≥30mm, a numerical aperture of 0.15-0.25, distortion ≤0.1%, and a total optical length of 80-90mm; Preferably, the distortion is ≤0.08%; Preferably, the lens has an IP67 dustproof and waterproof rating, making it suitable for outdoor ultraviolet security monitoring, high-voltage circuit arc detection, or camouflage target identification scenarios.

[0012] Optionally, the focal length of the first lens is -120mm to -130mm, and the center thickness is 2.5mm to 3.5mm; The second lens has a focal length of -140mm to -160mm and a center thickness of 2.5mm to 3.5mm; The third lens has a focal length of 170mm-190mm and a center thickness of 3.5mm-4.5mm; The fourth lens has a focal length of 150mm-170mm and a center thickness of 3.0mm-4.0mm.

[0013] Optionally, the fifth lens has a focal length of 300mm-340mm and a center thickness of 3.5mm-4.5mm; The sixth lens has a focal length of -90mm to -100mm and a center thickness of 2.0mm to 3.0mm. The seventh lens has a focal length of 270mm-290mm and a center thickness of 3.0mm-4.0mm; The eighth lens has a focal length of -210mm to -230mm and a center thickness of 2.5mm to 3.5mm.

[0014] Optionally, the telecentricity of both the object side and the image side is ≤0.15°, and the parallelism of the parallel optical path is ≤0.08°.

[0015] Optionally, the imaging surface is an ultraviolet-sensitive detector target surface, and the distance between it and the image-side end face of the rear lens group is 5mm-15mm.

[0016] The beneficial effects that this application can produce include: 1) This application employs a dual telecentric optical structure, with the telecentricity of both the object side and image side controlled within 0.2°. This effectively reduces magnification fluctuations caused by changes in object distance, ensuring consistent imaging size at different working distances and significantly improving imaging stability for large-scale outdoor monitoring. The front and rear lens groups form parallel optical paths, with the parallelism controlled within 0.1°. This facilitates the insertion of optical components such as beam splitters into the optical path without affecting imaging quality, while also enabling real-time monitoring of ultraviolet beams and capture of abnormal signals.

[0017] 2) This application features a dustproof and waterproof window at the front of the lens, made of sapphire material and coated with a hydrophobic and anti-fouling film. Combined with an overall IP67 protection rating, this allows the lens to withstand harsh outdoor environments, effectively resisting interference from external factors such as dust and rain, and extending the equipment's lifespan. The lens material is fused silica, coated with a 300nm-400nm ultraviolet anti-reflection film, achieving a transmittance of over 85%, significantly improving optical transmission performance in the ultraviolet band and enhancing detection sensitivity and signal capture capabilities.

[0018] 3) This application achieves a large field of view coverage of ≥60mm effective field of view on the object side and ≥30mm effective field of view on the image side by reasonably configuring the optical power distribution and surface shape combination of eight lenses, while controlling the distortion ≤0.1% and the total optical length within the range of 80-90mm. Under the premise of ensuring imaging quality, the structure is compact, reducing manufacturing costs and installation space requirements, which facilitates its application in security monitoring scenarios such as high-voltage circuit arc detection and camouflaged target identification. Attached Figure Description

[0019] Figure 1 A schematic diagram of the optical structure of a dual telecentric ultraviolet security monitoring lens provided in one embodiment of this application; Figure label: 1-Dustproof and waterproof window; 2-Front lens group; 21-First lens; 22-Second lens; 23-Third lens; 24-Fourth lens; 3-Beam splitter prism; 4-Aperture stop; 5-Rear lens group; 51-Fifth lens; 52-Sixth lens; 53-Seventh lens; 54-Eighth lens; 6-Imaging plane. Detailed Implementation

[0020] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following drawings indicate similar items; therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0021] To address the technical problems of insufficient telecentricity control accuracy and poor imaging stability in existing ultraviolet security monitoring lenses, this application provides a dual telecentric ultraviolet security monitoring lens. The dual telecentric ultraviolet security monitoring lens, arranged sequentially along the optical axis from the object side to the image side, includes a dustproof and waterproof window 1, a front lens group 2, a beam splitter prism 3, an aperture stop 4, a rear lens group 5, and an imaging plane 6. The lens adopts a dual telecentric structure, with telecentricity on both the object side and the image side ≤0.2°. The front lens group 2 and the rear lens group 5 form a parallel optical path, with the parallelism of the light rays in the parallel optical path ≤0.1°. The dustproof and waterproof window 1 adopts a circular flat plate structure and is installed at the front of the lens, fixed to the lens housing by a threaded connection. The front lens group 2 is composed of multiple lenses and is installed inside the front section of the lens barrel. The beam splitter 3 adopts a cubic structure and is located behind the front lens group 2. The aperture stop 4 is an adjustable circular stop located between the beam splitter 3 and the rear lens group 5. The rear lens group 5 is composed of multiple lenses and is installed inside the rear section of the lens barrel. The imaging surface 6 is the target surface of the ultraviolet sensitive detector, located at the rear end of the lens. The double telecentric structure is achieved by designing that the object-side principal ray is parallel to the optical axis and the image-side principal ray is parallel to the optical axis. The telecentricity is ensured by precise control of the lens curvature radius and spacing. The parallel light path is achieved by keeping the outgoing light rays of the front lens group 2 parallel to the incoming light rays of the rear lens group 5. The parallelism of the light rays is ensured by matching the optical power of the lens groups and controlling the positional accuracy. The double telecentric structure keeps the image size stable when the object distance changes, and the parallel light path facilitates the insertion of optical elements such as the beam splitter 3 in the light path without affecting the image quality. This implementation effectively solves the problem of unstable imaging caused by insufficient telecentricity of existing ultraviolet lenses, improves the imaging accuracy and consistency of large-scale outdoor monitoring, and provides an optical basis for spectroscopic monitoring functions.

[0022] To address the technical problems of unreasonable structure and insufficient chromatic aberration correction capability of existing ultraviolet lens front lens group 2, the front lens group 2 includes a first lens 21, a second lens 22, a third lens 23 and a fourth lens 24 arranged sequentially from the object side to the image side; the first lens 21 is a negative optical power biconcave spherical lens, the second lens 22 is a negative optical power crescent moon lens, the third lens 23 is a positive optical power biconvex spherical lens, and the fourth lens 24 is a positive optical power crescent moon lens. The first lens 21 is made of fused silica, with concave spherical surfaces on both sides, thinner at the center and thicker at the edges, and a negative optical power range of -120mm to -130mm. It is used to diverge incident light and correct spherical aberration. The second lens 22 is made of fused silica, with one concave spherical surface and one convex spherical surface, and a negative optical power range of -140mm to -160mm. It is used to further diverge light and correct coma. The third lens 23 is made of fused silica, with convex spherical surfaces on both sides, thicker at the center and thinner at the edges, and a positive optical power range of 170mm-190mm. It is used to converge light and correct chromatic aberration. The fourth lens 24 is made of fused silica, with one convex spherical surface and one concave spherical surface, and a positive optical power range of 150mm-170mm. It is used to adjust the optical path and correct astigmatism. The four lenses are installed sequentially through positioning steps inside the lens barrel. Adjacent lenses are spaced precisely by spacers, and the lenses are fixed to the lens barrel by elastic clamps. The front lens group 2 is responsible for receiving object-side light and performing preliminary imaging and aberration correction, while the combination of negative and positive lenses achieves chromatic aberration balance. This implementation effectively corrects spherical aberration, coma, and chromatic aberration in the ultraviolet band through the reasonable allocation of optical power and the combination of surface shapes of the four lenses, improving the optical performance of the front group and laying the foundation for the formation of subsequent parallel optical paths.

[0023] To address the technical problems of poor imaging quality and poor image plane flatness in existing ultraviolet lenses, the rear lens group 5 includes a fifth lens 51, a sixth lens 52, a seventh lens 53, and an eighth lens 54 arranged sequentially from the object side to the image side; the fifth lens 51 is a positive optical power biconvex spherical lens, the sixth lens 52 is a negative optical power biconcave spherical lens, the seventh lens 53 is a positive optical power biconvex spherical lens, and the eighth lens 54 is a negative optical power crescent moon lens. The fifth lens 51 is made of fused silica, with convex spherical surfaces on both sides, and a positive optical power range of 300mm-340mm. It is used to converge parallel light rays and correct field curvature. The sixth lens 52 is made of fused silica, with concave spherical surfaces on both sides, and a negative optical power range of -90mm to -100mm. It is used to diverge light rays and correct astigmatism. The seventh lens 53 is made of fused silica, with convex spherical surfaces on both sides, and a positive optical power range of 270mm-290mm. It is used to further converge light rays and correct distortion. The eighth lens 54 is made of fused silica, with one convex spherical surface and one concave spherical surface, and a negative optical power range of -210mm to -230mm. It is used to adjust the image plane position and correct chromatic aberration. The four lenses are installed sequentially through positioning steps inside the lens barrel. Adjacent lenses are spaced precisely by spacers, and the lenses are fixed to the lens barrel by elastic retaining rings. The rear lens group 5 is responsible for converging the parallel light rays onto the imaging plane to form a clear image. The combination of positive and negative lenses achieves aberration balance and image plane flatness. This implementation effectively corrects field curvature, astigmatism, and distortion in the ultraviolet band by rationally allocating the optical power and combining the surface shapes of the four lenses, ensuring image plane flatness and imaging clarity, and meeting the image quality requirements of security monitoring.

[0024] To address the technical issues of low light transmittance and poor protective performance of existing ultraviolet lens materials, the dustproof and waterproof window 1 is made of sapphire material with a hydrophobic and antifouling coating on its surface. Lenses 21 to 54 are all made of fused silica material with an ultraviolet antireflective coating on their surfaces. The dustproof and waterproof window 1 has a thickness of 3mm-5mm, a refractive index Nd=1.75-1.80, and a dispersion coefficient Vd=75-80. Sapphire material has high hardness and wear resistance, effectively resisting the impact of sand and dust in outdoor environments. The hydrophobic and antifouling coating is made of fluoride material and is deposited on the outer surface of the window using a vacuum evaporation process, with a contact angle greater than 110°, making it difficult for water droplets and stains to adhere. The first lens 21 to the eighth lens 54 are made of fused silica material with a refractive index Nd = 1.45-1.48 and a dispersion coefficient Vd = 65-70, exhibiting excellent transmittance in the ultraviolet band. The ultraviolet antireflective coating employs a multilayer dielectric film structure, deposited on both sides of the lens using an ion-assisted deposition process, with a total of 7-9 layers. The sapphire window is installed at the front of the lens via a threaded connection, and an O-ring seal is used between it and the lens barrel for waterproofing. The lenses are installed via positioning steps within the lens barrel, and spacers are used between adjacent lenses to maintain spacing. The sapphire window provides physical protection and blocks external contaminants, the hydrophobic and antifouling film reduces surface contamination, the fused silica material ensures ultraviolet transmittance, and the ultraviolet antireflective coating reduces surface reflection loss. This implementation significantly improves the lens's protective performance and optical transmittance, enabling the lens to adapt to harsh outdoor environments while ensuring high transmittance in the ultraviolet band and improving detection sensitivity.

[0025] To address the technical issues of narrow wavelength and low transmittance in existing ultraviolet lens antireflective coatings, this new antireflective coating achieves a wavelength range of 300nm-400nm and a transmittance of ≥85%. The antireflective coating employs a multi-layer dielectric film structure, consisting of alternating layers of high and low refractive index materials. The high-refractive-index material is titanium dioxide, and the low-refractive-index material is silicon dioxide. The total number of layers is 7-9, with the thickness of each layer optimized optically according to the target wavelength. The coating process utilizes ion-assisted deposition technology, with the substrate temperature controlled at 150℃-200℃ and the deposition rate controlled at 0.3nm / s-0.5nm / s. The film adhesion achieves a 5B rating through a cross-cut adhesion test. The antireflective coating is deposited on both surfaces of the first lens 21 to the eighth lens 54, reducing surface reflection and increasing transmitted light intensity through optical interference. This implementation enables the lens to achieve high transmittance in the 300nm-400nm ultraviolet band, reducing light loss, improving imaging brightness and detection sensitivity, and meeting the signal strength requirements of ultraviolet security monitoring.

[0026] To address the technical problem of existing ultraviolet lenses lacking spectral monitoring capabilities and unable to capture abnormal signals in real time, a beam splitter prism 3 is positioned between the front lens group 2 and the aperture stop 4 to monitor the ultraviolet beam and capture abnormal signals. The beam splitter prism 3 has a cubic structure, composed of two right-angled prisms bonded together. The bonded surface is coated with a beam-splitting film, achieving a splitting ratio of 90:10, meaning 90% of the light is transmitted to the rear lens group 5, and 10% is reflected to the lateral monitoring detector. The beam splitter prism 3 measures 10mm × 10mm × 10mm, is made of fused silica, and has an ultraviolet anti-reflection coating. The beam splitter prism 3 is fixed inside the lens barrel by a bracket connected to the lens barrel with screws, maintaining a positional accuracy within ±0.05mm. The beam splitter prism 3 reflects a portion of the ultraviolet light to the laterally mounted monitoring detector, which uses an ultraviolet photodiode to monitor changes in ultraviolet light intensity in real time. The beam splitter prism 3 separates the main imaging optical path from the monitoring optical path, and the monitoring detector captures abnormal ultraviolet signals and triggers an alarm. This implementation method achieves real-time monitoring of ultraviolet beams without hindering the main imaging function, enabling timely detection of abnormal signals such as high-voltage circuit arcs and improving the early warning capability of security monitoring.

[0027] To address the technical issues of small field of view and large distortion in existing ultraviolet lenses, the effective field of view on the object side of the lens is ≥60mm, the effective field of view on the image side is ≥30mm, the numerical aperture is 0.15-0.25, the distortion is ≤0.1%, and the total optical length is 80-90mm. The effective field of view on the object side is achieved through the aperture and focal length design of the front lens group 2, with a front aperture of 25mm-30mm to ensure a large field of view for light incidence. The effective field of view on the image side is achieved through the image-side field of view design of the rear lens group 5, with an image-side field of view of 15°-20°. The numerical aperture is achieved through the matching of the aperture and focal length of the aperture stop 4, with an aperture of 3mm-5mm, matching the system focal length to obtain a numerical aperture of 0.15-0.25. Distortion is controlled through the optical power distribution and surface shape optimization of the lens group, and a symmetrical lens layout is used to reduce distortion. The overall optical length is controlled through the lens spacing and the lens barrel length, with the lens barrel made of aluminum alloy and a length of 80-90mm. The large field of view design allows the lens to cover a wider monitoring area, the low distortion design ensures image geometric accuracy, and the compact overall optical length facilitates installation and integration. This implementation achieves a wide field of view, low distortion, and compact optical design, meeting the dual requirements of outdoor security monitoring for coverage and image quality, while also facilitating equipment installation and spatial layout.

[0028] Addressing the technical limitations of existing ultraviolet lenses in terms of low protection levels and restricted application scenarios, this lens boasts an IP67 dust and water resistance rating, making it suitable for outdoor ultraviolet security monitoring, high-voltage circuit arc detection, and camouflage target identification. The IP67 protection rating is achieved through the following measures: two O-rings are installed between the dust and water-resistant window 1 and the lens barrel, using silicone rubber with a compression rate controlled at 25%-30%; the lens barrel is a one-piece aluminum alloy structure with an anodized surface, and laser welding is used at the joints; the lens is fixed to the lens barrel with an elastic retaining ring, and a sealing ring is installed between the retaining ring and the lens barrel; the rear end of the lens is threaded to the detector interface and also has a sealing ring. In outdoor ultraviolet security monitoring scenarios, the lens is mounted on a monitoring pole or bracket, facing the monitored area; in high-voltage circuit arc detection scenarios, the lens is aimed at high-voltage transmission lines to detect the ultraviolet radiation generated by the arc; in camouflage target identification scenarios, the lens utilizes the differences in the reflectivity of camouflage materials in the ultraviolet band for identification. The sealed structure prevents dust and moisture from entering the lens, and the protective design allows the lens to withstand harsh environments such as rain and sandstorms. This implementation method enables the lens to have excellent adaptability to outdoor environments, expands the application scope of ultraviolet lenses in the field of security monitoring, and meets the usage needs of various special scenarios.

[0029] To address the technical issues of unclear parameters and low manufacturing precision in existing ultraviolet lenses, the following lens designs are proposed: the first lens 21 has a focal length of -120mm to -130mm and a center thickness of 2.5mm to 3.5mm; the second lens 22 has a focal length of -140mm to -160mm and a center thickness of 2.5mm to 3.5mm; the third lens 23 has a focal length of 170mm to 190mm and a center thickness of 3.5mm to 4.5mm; and the fourth lens 24 has a focal length of 150mm to 170mm and a center thickness of 3.0mm to 4.0mm. The first lens 21 adopts a double-concave spherical design, with radii of curvature of -80mm to -90mm and -100mm to -110mm on the two surfaces, respectively. The center thickness machining tolerance is controlled within ±0.05mm, and the surface shape accuracy is controlled within λ / 4@632.8nm. The second lens 22 adopts a meniscus design, with a concave surface curvature radius of -120mm to -130mm and a convex surface curvature radius of -150mm to -160mm. The center thickness machining tolerance is controlled within ±0.05mm, and the surface shape accuracy is controlled within λ / 4@632.8nm. The third lens 23 adopts a biconvex spherical design with radii of curvature of 100mm to 110mm and 120mm to 130mm on the two sides, respectively. The center thickness processing tolerance is controlled within ±0.05mm, and the surface shape accuracy is controlled within λ / 4@632.8nm. The fourth lens 24 adopts a meniscus design with a convex surface curvature radius of 90mm to 100mm and a concave surface curvature radius of -140mm to -150mm. The center thickness processing tolerance is controlled within ±0.05mm, and the surface shape accuracy is controlled within λ / 4@632.8nm. The lens processing adopts a precision grinding and polishing process, with a surface roughness Ra≤5nm and eccentricity controlled within 0.01mm. Precise control of the front lens parameters ensures a reasonable distribution of optical power, realizing aberration correction and parallel optical path formation. This embodiment ensures the stability of the optical performance of the front lens group 2 through precise lens parameter control, providing a guarantee for the realization of the bi-telecentric structure and parallel optical path, and improving the consistency of imaging quality.

[0030] To address the technical issues of unclear parameters and unstable image quality in existing ultraviolet lenses, the fifth lens 51 has a focal length of 300mm-340mm and a center thickness of 3.5mm-4.5mm; the sixth lens 52 has a focal length of -90mm to -100mm and a center thickness of 2.0mm-3.0mm; the seventh lens 53 has a focal length of 270mm-290mm and a center thickness of 3.0mm-4.0mm; and the eighth lens 54 has a focal length of -210mm to -230mm and a center thickness of 2.5mm-3.5mm. The fifth lens 51 adopts a biconvex spherical design, with radii of curvature of 150mm to 170mm and 180mm to 200mm on the two sides, respectively. The center thickness machining tolerance is controlled within ±0.05mm, and the surface shape accuracy is controlled within λ / 4@632.8nm. The sixth lens 52 adopts a biconcave spherical design, with radii of curvature of -60mm to -70mm and -80mm to -90mm on the two sides, respectively. The center thickness machining tolerance is controlled within ±0.05mm, and the surface shape accuracy is controlled within λ / 4@632.8nm. The seventh lens... Lens 53 employs a biconvex spherical design, with radii of curvature of 140mm to 150mm and 160mm to 170mm on its two surfaces, respectively. The center thickness machining tolerance is controlled within ±0.05mm, and the surface shape accuracy is controlled within λ / 4@632.8nm. Lens 54 employs a meniscus design, with a convex surface curvature radius of -180mm to -190mm and a concave surface curvature radius of -220mm to -240mm. The center thickness machining tolerance is controlled within ±0.05mm, and the surface shape accuracy is controlled within λ / 4@632.8nm. Lens processing utilizes precision grinding and polishing processes, achieving a surface roughness Ra≤5nm and eccentricity controlled within 0.01mm. Precise control of the rear lens parameters ensures aberration correction and image plane flatness, achieving high-quality imaging. This implementation, through precise lens parameter control, ensures stable optical performance of the rear lens group 5, effectively corrects field curvature, astigmatism, and distortion, and improves image plane quality and image sharpness.

[0031] To address the technical issues of unclear parameters and poor protective effect of existing UV lens protective windows, the dustproof and waterproof window 1 has a thickness of 3mm-5mm, a refractive index Nd=1.75-1.80, and a dispersion coefficient Vd=75-80. The dustproof and waterproof window 1 is made of sapphire material, and its thickness is designed to balance protective strength and optical performance. A thickness of 3mm is suitable for general protection needs, while a thickness of 5mm is suitable for high-impact environments. The refractive index of 1.75-1.80 ensures optical matching with subsequent lenses and reduces interface reflection; the dispersion coefficient of 75-80 ensures chromatic aberration control in the UV band. Both sides of the window are polished, with a surface roughness Ra≤5nm and parallelism controlled within 0.01mm. The window edges are chamfered with a chamfer size of 0.2mm×45° to prevent edge chipping. A hydrophobic and antifouling film is coated on the outer surface of the window, with a film thickness of 100nm-150nm and a contact angle greater than 110°. The window is installed at the front of the lens via a threaded connection, and two O-rings are installed between it and the lens barrel, with the compression rate of the O-rings controlled at 25%-30%. The sapphire window provides high-strength physical protection, optical parameter matching ensures image quality, and a hydrophobic coating reduces surface contamination. This implementation allows the protective window to possess both excellent mechanical and optical performance, effectively protecting the internal lens from external environmental damage while not affecting the transmission of ultraviolet light.

[0032] To address the technical issues of insufficient telecentricity and parallelism control precision in existing ultraviolet lenses, the telecentricity on both the object and image sides is ≤0.15°, the parallelism of the parallel light path is ≤0.08°, and the distortion is ≤0.08%. Telecentricity is achieved through precise control of the lens curvature radius, thickness, and spacing. Object-side telecentricity is controlled by the power distribution of the front lens group 2 and the position of the aperture stop 4, while image-side telecentricity is controlled by the power distribution of the rear lens group 5 and the position of the imaging plane. Light parallelism is achieved by matching the outgoing rays from the front lens group 2 with the incoming rays from the rear lens group 5, with the power ratio between the front and rear lens groups controlled within the range of 1:1.2-1:1.5. Distortion is controlled through symmetrical lens group layout and aspherical optimization, using optical design software for iterative optimization. Telecentricity detection uses a collimator with an angle measuring instrument, parallelism detection uses a shearing interferometer, and distortion detection uses a grid target with image processing software. High-precision telecentricity and parallelism ensure image size stability and compatibility with optical path insertion elements, while low distortion guarantees image geometric accuracy. This implementation further enhances the lens's optical precision, meeting the application requirements of high-precision ultraviolet imaging and measurement, and providing an optical foundation for functions such as spectroscopic monitoring.

[0033] To address the technical issues of unreasonable aperture stop placement and poor stray light control in existing ultraviolet lenses, aperture stop 4 has an aperture of 3mm-5mm and is located between the beam splitter prism 3 and the rear lens group 5. Aperture stop 4 employs an adjustable circular aperture stop structure composed of multiple blades (6-8 blades) made of stainless steel with a blackened surface to reduce reflection. The aperture stop diameter is controlled by an adjustment ring, with an adjustment range of 3mm-5mm and an adjustment accuracy of 0.1mm. The aperture stop is installed in an aperture stop mount within the lens barrel, with the mount connected to the lens barrel by a thread, and its positional accuracy controlled within ±0.05mm. Anti-stray light stops are placed before and after the main aperture stop, with their inner surfaces coated with black matte paint, resulting in a reflectivity of less than 5%. Aperture stop 4 controls the light throughput and numerical aperture entering the lens while blocking stray light. Its position behind the beam splitter prism 3 avoids affecting the beam splitting function and facilitates control of the rear lens group's light angle. This implementation achieves a balanced control of light flux and imaging quality, effectively suppresses stray light, improves image contrast and signal-to-noise ratio, and provides convenience for numerical aperture adjustment.

[0034] To address the technical issues of unclear lens material parameters and unstable optical performance in existing ultraviolet lenses, the refractive index Nd of the first lens 21 to the eighth lens 54 is 1.45-1.48, and the dispersion coefficient Vd is 65-70. The lens material is fused silica, using Corning 7980 or a material of equivalent performance, with a refractive index of 1.45-1.48 and a dispersion coefficient of 65-70 at a wavelength of 365 nm. Material uniformity is controlled within ±5×10^-6, and fringe is controlled within level 1. Internal bubbles and impurities are controlled within level 1. The lens blank undergoes annealing to eliminate internal stress, and stress birefringence is controlled within 5 nm / cm. Fused silica material exhibits excellent transmittance in the ultraviolet band, with a transmittance greater than 90% in the 300nm-400nm band; low dispersion characteristics are beneficial for chromatic aberration correction in the ultraviolet band; and high thermal stability ensures stable lens performance under varying temperature conditions. This implementation ensures stable and consistent optical performance of the lens material, providing a material basis for high transmittance and low chromatic aberration in the ultraviolet band, and improving the lens's environmental adaptability and image quality stability.

[0035] To address the technical issues of unclear positioning and low assembly precision of existing ultraviolet lenses' imaging surface 6, the imaging surface 6 is the target surface of the ultraviolet sensitive detector, with a distance of 5mm-15mm between it and the image-side end face of the rear lens group 5. The ultraviolet sensitive detector employs a back-illuminated ultraviolet CCD or CMOS sensor with a pixel size of 5μm-10μm and a target surface size of 1 / 2 inch to 2 / 3 inch. The detector is mounted to the rear of the lens via a flange interface, using a standard C-mount or CS-mount. The distance between the detector target surface and the lens image plane is adjusted by a focusing mechanism employing a precision thread structure with a pitch of 0.5mm, an adjustment range of 5mm-15mm, and an adjustment precision of 0.01mm. A sealing ring is installed between the detector and the lens barrel to ensure the protection level. The detector circuit board is connected to external devices via a flexible cable. Precise control of the imaging surface 6 position ensures optical matching between the lens and the detector, and the focusing mechanism achieves clear imaging at different working distances. This implementation ensures precise assembly and optical matching between the lens and the detector, achieving high-quality ultraviolet image acquisition while guaranteeing protective performance and reliable electrical connections.

[0036] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A dual telecentric ultraviolet security monitoring lens, characterized in that, Along the optical axis from the object side to the image side, there are a dustproof and waterproof window (1), a front lens group (2), a beam splitter (3), an aperture stop (4), a rear lens group (5), and an imaging surface (6). The lens adopts a double telecentric structure, with the telecentricity of both the object side and the image side being ≤0.2°; the front lens group (2) and the rear lens group (5) are parallel optical paths, and the parallelism of the light rays in the parallel optical path is ≤0.1°.

2. The dual telecentric ultraviolet security monitoring lens according to claim 1, characterized in that, The front lens group (2) includes a first lens (21), a second lens (22), a third lens (23) and a fourth lens (24) arranged sequentially from the object side to the image side. The first lens (21) is a biconcave spherical lens with negative optical power, the second lens (22) is a crescent moon lens with negative optical power, the third lens (23) is a biconvex spherical lens with positive optical power, and the fourth lens (24) is a crescent moon lens with positive optical power.

3. The dual telecentric ultraviolet security monitoring lens according to claim 2, characterized in that, The rear lens group (5) includes a fifth lens (51), a sixth lens (52), a seventh lens (53) and an eighth lens (54) arranged sequentially from the object side to the image side; The fifth lens (51) is a biconvex spherical lens with positive optical power, the sixth lens (52) is a biconcave spherical lens with negative optical power, the seventh lens (53) is a biconvex spherical lens with positive optical power, and the eighth lens (54) is a crescent-shaped lens with negative optical power. Preferably, the refractive index of the first lens (21) to the eighth lens (54) is Nd=1.45-1.48 and the dispersion coefficient is Vd=65-70.

4. The dual telecentric ultraviolet security monitoring lens according to claim 1, characterized in that, The dustproof and waterproof window (1) is made of sapphire material and has a hydrophobic and anti-fouling film on its surface; The first lens (21) to the eighth lens (54) are all made of fused silica material and are coated with an ultraviolet anti-reflective film on their surfaces; Preferably, the ultraviolet antireflective film has a wavelength range of 300nm-400nm and a transmittance of ≥85%; Preferably, the thickness of the dustproof and waterproof window (1) is 3mm-5mm, the refractive index is Nd=1.75-1.80, and the dispersion coefficient is Vd=75-80.

5. The dual telecentric ultraviolet security monitoring lens according to claim 1, characterized in that, The beam splitter (3) is positioned between the front lens group (2) and the aperture stop (4) to monitor the ultraviolet beam and capture abnormal signals; Preferably, the aperture stop (4) has an aperture of 3mm-5mm and is located between the beam splitter (3) and the rear lens group (5).

6. The dual telecentric ultraviolet security monitoring lens according to claim 1, characterized in that, The lens has an effective field of view on the object side ≥60mm, an effective field of view on the image side ≥30mm, a numerical aperture of 0.15-0.25, distortion ≤0.1%, and a total optical length of 80-90mm. Preferably, the distortion is ≤0.08%; Preferably, the lens has an IP67 dustproof and waterproof rating, making it suitable for outdoor ultraviolet security monitoring, high-voltage circuit arc detection, or camouflage target identification scenarios.

7. The dual telecentric ultraviolet security monitoring lens according to claim 2, characterized in that, The focal length of the first lens (21) is -120mm to -130mm, and the center thickness is 2.5mm to 3.5mm; The second lens (22) has a focal length of -140mm to -160mm and a center thickness of 2.5mm to 3.5mm; The focal length of the third lens (23) is 170mm-190mm, and the center thickness is 3.5mm-4.5mm; The fourth lens (24) has a focal length of 150mm-170mm and a center thickness of 3.0mm-4.0mm.

8. The dual telecentric ultraviolet security monitoring lens according to claim 3, characterized in that, The fifth lens (51) has a focal length of 300mm-340mm and a center thickness of 3.5mm-4.5mm; The sixth lens (52) has a focal length of -90mm to -100mm and a center thickness of 2.0mm to 3.0mm; The seventh lens (53) has a focal length of 270mm-290mm and a center thickness of 3.0mm-4.0mm; The eighth lens (54) has a focal length of -210mm to -230mm and a center thickness of 2.5mm to 3.5mm.

9. The dual telecentric ultraviolet security monitoring lens according to claim 1, characterized in that, The telecentricity of both the object side and the image side is ≤0.15°, and the parallelism of the parallel optical path is ≤0.08°.

10. The dual telecentric ultraviolet security monitoring lens according to claim 1, characterized in that, The imaging surface (6) is the ultraviolet-sensitive detector target surface, and the distance between it and the image-side end face of the rear lens group (5) is 5mm-15mm.

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