High-transmission ultraviolet fluorescence detection lens

Abstract

This application discloses a high-transmittance ultraviolet fluorescence detection lens, relating to the field of optical lenses. It addresses the problems of insufficient transmittance, severe fluorescence signal attenuation, and poor image quality in existing ultraviolet fluorescence detection lenses. The lens is constructed by sequentially arranging an object surface protection window, a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, and an image plane along the optical axis from the object side to the image side. The object surface protection window is made of calcium fluoride, and at least a portion of the first to fifth lenses are made of calcium fluoride and at least a portion of fused silica. Each lens surface is coated with an ultraviolet antireflection film. By combining calcium fluoride and fused silica to optimize ultraviolet transmittance, and using a multi-layer ultraviolet antireflection film to reduce surface reflection loss, the lens achieves an overall transmittance of over 88% in the 250nm-380nm band. This effectively reduces fluorescence signal attenuation, significantly improves image brightness and contrast, and achieves good aberration correction. The compact structure makes it suitable for mass production applications.

Description

Technical Field

[0001] This application relates to a high-transmittance ultraviolet fluorescence detection lens, belonging to the field of optical lens technology. Background Technology

[0002] In the field of fluorescence detection technology, ultraviolet (UV) optical lenses, as core components of imaging systems, are widely used in scenarios such as biofluorescence detection, forensic fingerprint fluorescence display, and food fluorescence detection. Existing UV fluorescence detection lenses typically employ a multi-lens optical structure, with the objective lens group, aperture, and image lens group arranged sequentially along the optical axis. The UV fluorescence signal is transmitted to the detector through the refraction and focusing effects of the lenses. Regarding material selection, current technologies primarily use ordinary optical glass or a single type of UV-transmitting material to make the lenses. Some high-end lenses utilize special materials such as calcium fluoride and fused silica to enhance UV transmittance. Simultaneously, to reduce light reflection loss on the lens surface, an anti-reflection coating is usually deposited on the lens surface to improve overall optical transmittance.

[0003] However, the current problems are: existing ultraviolet fluorescence detection lenses generally have insufficient transmittance in the ultraviolet band, resulting in severe attenuation of fluorescence signals during transmission, which directly affects the brightness and contrast of the image; some lenses use ordinary optical glass materials, which cannot effectively adapt to the high transmittance requirements of the ultraviolet band, resulting in the inability to clearly present fluorescence details; while when using special high-transmittance ultraviolet materials, there are often problems with complex optical structures and poor aberration correction, resulting in a decline in image quality; in addition, existing technical solutions are difficult to balance between material selection and cost control, and lenses with complex structures are difficult to manufacture and costly, making it difficult to meet the needs of mass applications.

[0004] Therefore, how to design an ultraviolet fluorescence detection lens that can ensure high ultraviolet transmittance, good aberration correction effect, control cost, and is suitable for mass production has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This invention relates to a high-transmittance ultraviolet fluorescence detection lens. The technical problem this invention aims to solve is that existing ultraviolet fluorescence detection lenses generally have insufficient transmittance in the ultraviolet band, resulting in severe attenuation of the fluorescence signal during transmission, directly affecting the brightness and contrast of the image; some lenses use ordinary optical glass materials, which cannot effectively meet the high transmittance requirements of the ultraviolet band; while when using special high-transmittance ultraviolet materials, there are often problems such as complex optical structures and poor aberration correction, leading to a decline in image quality; in addition, existing technical solutions are difficult to balance between material selection and cost control, and lenses with complex structures are difficult to manufacture and costly, making it difficult to meet the needs of mass applications.

[0006] To achieve the above objectives, this application provides the following technical solution: A high-transmittance ultraviolet fluorescence detection lens, wherein the optical axis from the object side to the image side includes, in sequence, an object surface protection window, a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens and an image plane; The surface protection window is made of calcium fluoride material; Of the first to the fifth lenses, at least some lenses are made of calcium fluoride material and at least some lenses are made of fused silica material; The surfaces of the first to fifth lenses are coated with ultraviolet anti-reflection films.

[0007] Optionally, the first lens is a biconvex spherical lens with positive optical power, made of calcium fluoride material; The second lens is a negative optical power biconcave spherical lens made of fused silica material; The third lens is a positive optical power curved moon lens, made of calcium fluoride material; The fourth lens is a positive optical power biconvex spherical lens made of fused silica material; The fifth lens is a negative optical power crescent moon lens, made of calcium fluoride material.

[0008] Optionally, the ultraviolet antireflection film has a multilayer structure, with a wavelength range of 250nm-380nm and a single-sided transmittance of ≥92%.

[0009] Optionally, the aperture stop is disposed between the third lens and the fourth lens, and the aperture of the aperture stop is 3-4 mm.

[0010] Optionally, the aperture size of the aperture stop can be adjusted according to the fluorescence intensity.

[0011] Optionally, the lens has a focal length of 25-30mm, a numerical aperture of 0.3-0.4, distortion ≤0.15%, and an optical length of 60-70mm.

[0012] Optionally, the lens has an overall transmittance of ≥88% in the 250nm-380nm wavelength band.

[0013] Optionally, the calcium fluoride material has a refractive index of Nd=1.43 and a dispersion coefficient of Vd=95; The fused silica material has a refractive index of Nd=1.46 and a dispersion coefficient of Vd=67.8.

[0014] Optionally, the thickness of the object surface protection window is 2-5mm, which is used to protect the internal lens assembly without affecting the transmission of ultraviolet light.

[0015] Optionally, the center thickness of the first lens is 3.5-4.5 mm, the center thickness of the second lens is 2.0-3.0 mm, the center thickness of the third lens is 2.5-4.0 mm, the center thickness of the fourth lens is 3.0-4.0 mm, and the center thickness of the fifth lens is 2.5-3.5 mm.

[0016] The beneficial effects that this application can produce include: 1) This application adopts an optical design that combines calcium fluoride material and fused silica material. Calcium fluoride material has excellent transmittance and low dispersion characteristics in the ultraviolet band, while fused silica material has good mechanical stability and moderate refractive index. The combination of the two materials can effectively correct chromatic aberration and spherical aberration in the ultraviolet band and significantly improve imaging quality.

[0017] 2) This application achieves efficient collection and precise focusing of ultraviolet fluorescence signals by rationally allocating the optical power and configuring the surface of five lenses, with positive and negative lenses arranged alternately.

[0018] 3) The protective window of this application also uses calcium fluoride material, which protects the internal lens assembly from contamination and damage without reducing the transmittance in the ultraviolet band.

[0019] 4) The ultraviolet anti-reflection coating deposited on the lens surface of this application can increase the single-sided transmittance to over 92%. Combined with the high transmittance characteristics of the material itself, the overall transmittance of the lens in the 250nm-380nm band reaches over 88%, effectively reducing the attenuation of fluorescence signals during transmission.

[0020] 5) The aperture stop of this application is set in the middle position of the optical system, which is beneficial to control stray light and optimize imaging contrast.

[0021] 6) The overall optical structure of this application is compact, with the total optical length controlled within the range of 60-70mm and distortion less than 0.15%, achieving good image quality while ensuring high transmittance.

[0022] 7) The technical solution of this application achieves a good balance between material selection, optical performance and cost control, and is suitable for mass production and wide application. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the optical structure of a high-transmittance ultraviolet fluorescence detection lens provided in one embodiment of this application; Figure 2 A schematic diagram of the transmittance curve of a high-transmittance ultraviolet fluorescence detection lens provided in one embodiment of this application; Figure 3 This is a schematic diagram of the fluorescence imaging effect of a high-transmittance ultraviolet fluorescence detection lens provided in one embodiment of this application; Figure label: 10-High-transmittance ultraviolet fluorescence detection lens; 11-Object plane protection window; 12-First lens; 13-Second lens; 14-Third lens; 15-Aperture stop; 16-Fourth lens; 17-Fifth lens; 18-Image plane. Detailed Implementation

[0024] 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.

[0025] In existing technologies, ultraviolet fluorescence detection lenses suffer from insufficient transmittance in the ultraviolet band, severe fluorescence signal attenuation, and difficulty in balancing material selection and cost control, resulting in poor image quality. To address these technical problems, this embodiment provides the following technical solution: Please refer to Figure 1-3 As shown, this application provides a high-transmittance ultraviolet fluorescence detection lens, the optical axis of which, from the object side to the image side, includes an object surface protection window 11, a first lens 12, a second lens 13, a third lens 14, an aperture stop 15, a fourth lens 16, a fifth lens 17, and an image plane 18 in sequence; the object surface protection window 11 is made of calcium fluoride material; among the first lens 12 to the fifth lens 17, at least some lenses are made of calcium fluoride material, and at least some lenses are made of fused silica material; the surfaces of the first lens 12 to the fifth lens 17 are coated with an ultraviolet anti-reflection film.

[0026] It should be noted that the object protection window 11 is located at the very front of the high-transmittance ultraviolet fluorescence detection lens 11, directly facing the object being detected. It is made of calcium fluoride crystal material, which has excellent transmittance in the ultraviolet band, with a thickness ranging from 2-5 mm. A precision polishing process ensures a surface roughness of less than 10 nm. The first lens 12 to the fifth lens 17 constitute the core optical components of the high-transmittance ultraviolet fluorescence detection lens 10. The calcium fluoride material is optical-grade CaF2 crystal, and the fused silica material is JGS1 grade quartz glass. The two materials are arranged sequentially through optical bonding or air separation. The ultraviolet antireflective coating adopts a multi-layer dielectric film structure, deposited on the surface of each lens through a vacuum evaporation process. The film materials include magnesium fluoride, silicon dioxide, etc. The image plane 18 is located at the end of the high-transmittance ultraviolet fluorescence detection lens 10 and is used to mount a CCD or CMOS image sensor.

[0027] When the high-transmittance ultraviolet fluorescence detection lens 10 of this application is working, the ultraviolet fluorescence signal is incident from the object side, passes sequentially through the object surface protection window 11 and the five lens group, and is focused on the image plane 18 by the aperture stop 15 to control the beam aperture and finally received by the detector. The high ultraviolet transmittance characteristics of calcium fluoride and fused silica materials, combined with the antireflection coating, ensure that the signal attenuation is minimized during transmission.

[0028] With this embodiment, the high-transmittance ultraviolet fluorescence detection lens 10 achieves an overall transmittance of over 88% in the 250nm-380nm band, effectively reducing fluorescence signal attenuation; the object surface protection window 11 protects the internal lens from contamination without reducing ultraviolet transmittance; the combination of calcium fluoride and fused silica material achieves effective correction of chromatic aberration and spherical aberration, significantly improving imaging quality; the overall structure is compact, suitable for mass production and widespread application.

[0029] As an example, in lens optical structure design, the optical power and surface shape configuration of each lens directly affect image quality and aberration correction effect. In existing technologies, unreasonable lens configuration leads to significant aberrations. To address the above technical problems, this embodiment provides the following technical solution: Please refer to Figure 1-3 As shown, the first lens 12 is a biconvex spherical lens with positive optical power, made of calcium fluoride material; the second lens 13 is a biconcave spherical lens with negative optical power, made of fused silica material; the third lens 14 is a crescent-shaped lens with positive optical power, made of calcium fluoride material; the fourth lens 16 is a biconvex spherical lens with positive optical power, made of fused silica material; and the fifth lens 17 is a crescent-shaped lens with negative optical power, made of calcium fluoride material.

[0030] It should be noted that in the first lens 12, with its biconvex spherical structure, the object-side radius of curvature is 15-20 mm, the image-side radius of curvature is 18-22 mm, and the central thickness is 3.5-4.5 mm. The positive optical power causes the incident light rays to converge. In the second lens 13, with its biconcave spherical structure, the object-side radius of curvature is -12-15 mm, the image-side radius of curvature is -10-13 mm, and the central thickness is 2.0-3.0 mm. The negative optical power is used to correct the chromatic aberration produced by the first lens 12. In the third lens 14, with its crescent-shaped structure, the object side is convex and the image side is concave, with radii of curvature of 25-30 mm and -20-25 mm respectively, and a central thickness of 2.5-4.0 mm, further correcting astigmatism and field curvature. The fourth lens 16, with its biconvex spherical structure similar to the first lens 12, has radii of curvature of 16-20 mm and 18-22 mm, and a central thickness of 3.0-4.0 mm, enhancing the converging ability. In the fifth lens's 17-curved lunar surface structure, the object side is concave and the image side is convex, with radii of curvature of -18-22mm and 20-25mm respectively, and a center thickness of 2.5-3.5mm. These lenses are used to correct residual aberrations and optimize image surface flatness. Each lens is fixed by a precision lens barrel, and spacers are placed between adjacent lenses to control the air gap.

[0031] The alternating arrangement of positive and negative lenses in the optical power configuration allows the system's chromatic aberration to be fully corrected. The dispersion characteristics of calcium fluoride and fused silica are complementary, and the combination of biconvex, biconcave, and meniscus shapes effectively balances spherical aberration, coma, astigmatism, and field curvature.

[0032] With this implementation method, the distortion of the high-transmittance ultraviolet fluorescence detection lens 10 is controlled within 0.15%, and the imaging clarity of each field of view is consistent; the reasonable allocation of positive and negative optical power enhances the stability of the optical system; the combination of five different surface-type lenses achieves efficient collection and precise focusing of ultraviolet fluorescence signals, and significantly improves imaging contrast and resolution.

[0033] As an example, reflection loss at the lens surface reduces overall transmittance, and existing antireflective coatings are insufficient in the ultraviolet band, making it difficult to achieve ideal transmittance on a single side. To address the above technical problems, this embodiment provides the following technical solution: Please refer to Figure 1-3 As shown, the ultraviolet antireflection film has a multilayer film structure, the wavelength range of the antireflection film is 250nm-380nm, and the single-sided transmittance is ≥92%.

[0034] It should be noted that the UV antireflective coating adopts a 15-25 layer dielectric film stacked structure, with magnesium fluoride (MgF2) and silicon dioxide (SiO2) alternating as the film materials. The coating is deposited in a vacuum coating machine using an ion-assisted deposition process. The thickness of each layer is controlled at λ / 4 of the optical thickness, and the center wavelength is set at 315nm to cover the entire UV band of 250nm-380nm. Before coating, the lens surface needs to undergo ultrasonic cleaning and plasma activation treatment to ensure film adhesion. After coating, the transmittance of each lens surface is measured using a spectrophotometer, and the single-sided transmittance is not less than 92%. The film hardness reaches 3H or higher, and the environmental resistance test meets the requirement of no peeling after 50 cycles at temperatures ranging from -40℃ to +80℃. In practical applications, other layer numbers and material combinations can be selected for this film structure; this application does not limit this.

[0035] Multilayer film structures reduce surface reflection through the principle of interference cancellation, and the refractive index gradient design of each film layer causes phase cancellation of reflected light at different interfaces, thereby maximizing transmittance.

[0036] With this implementation, the surface reflection loss of a single lens is reduced from 4% to below 8%, and the cumulative transmission loss of the five lenses is significantly reduced; the wide-band anti-reflection design ensures consistent performance across the entire 250nm-380nm band; the film durability ensures stable transmittance of the high-transmittance ultraviolet fluorescence detection lens 10 during long-term use, and reduces maintenance costs.

[0037] As an example, the position and size of the aperture stop 15 affect imaging contrast and stray light control. In the prior art, unreasonable aperture stop settings lead to a decrease in image quality. To address the above technical problems, this embodiment provides the following technical solution: Please refer to Figure 1-3 As shown, the aperture stop 15 is disposed between the third lens 14 and the fourth lens 16, and the aperture of the aperture stop 15 is 3-4 mm.

[0038] It should be noted that the aperture stop 15 is laser-cut from a thin stainless steel sheet with a thickness of 0.1-0.2 mm, and the surface is blackened to reduce stray light reflection. The aperture stop 15 is installed within the lens barrel cavity between the third lens 14 and the fourth lens 16, achieving precise axial positioning through a positioning step and radial fixation using an interference fit. The aperture diameter is machined with an accuracy controlled within ±0.02 mm, and the edges are chamfered to avoid diffraction effects. The aperture stop 15 is located in the middle region of the optical system, where the beam is narrowest, which is beneficial for effectively controlling the beam aperture and blocking edge stray light.

[0039] The aperture stop 15 is located in the middle of the optical system, which limits the aperture of the incident beam, blocks stray light rays incident at large angles, and controls the numerical aperture and depth of field of the system.

[0040] After adopting this implementation method, the imaging contrast is improved by more than 20%, and stray light is effectively suppressed; the optimized position of aperture stop 15 makes the main ray angle more reasonable and improves the uniformity of image plane illumination; the 3-4mm aperture size matches the lens focal length, and the numerical aperture is controlled within the range of 0.3-0.4, taking into account both resolution and depth of field requirements.

[0041] As an example, the fixed aperture stop 15 cannot adapt to scenes with different fluorescence intensities, leading to overexposure or insufficient signal. To address the above technical problems, this embodiment provides the following technical solution: Please refer to Figure 1-3 As shown, the aperture size of the aperture stop 15 can be adjusted according to the fluorescence intensity.

[0042] It should be noted that the aperture stop 15 adopts an adjustable aperture structure, composed of multiple arc-shaped blades, with 8-12 blades, made of thin stainless steel with a blackened surface. The blades are connected to an external adjusting ring via a linkage mechanism. Rotating the adjusting ring synchronously drives the blades to open and close, achieving continuous adjustment of the aperture from 2mm to 5mm. The adjusting ring is equipped with scale markings, allowing operators to quickly set the appropriate aperture based on fluorescence intensity. The adjusting mechanism is equipped with a damping device to prevent unexpected changes in the aperture during use. The linkage mechanism is precision-machined to ensure good synchronization of blade movement and that the aperture shape always remains circular. In practical applications, this adjusting structure can also be driven by a motor or other automated control methods; this embodiment does not limit this.

[0043] The incident light flux is controlled by adjusting the aperture size. In strong fluorescence scenarios, the aperture is reduced to avoid detector saturation, while in weak fluorescence scenarios, the aperture is increased to increase the amount of signal collected.

[0044] With this implementation method, the high-transmittance ultraviolet fluorescence detection lens 10 is more adaptable to different fluorescence intensity detection scenarios, and its dynamic range is expanded; operators can make flexible adjustments according to actual conditions without replacing the lens; an electric adjustment mechanism can be integrated into the automated detection system to achieve automatic aperture optimization and improve detection efficiency.

[0045] As an example, the overall optical performance parameters of the high-transmittance ultraviolet fluorescence detection lens 10 directly affect the detection accuracy and applicable range. In existing technologies, unreasonable parameter matching leads to application limitations. To address the above technical problems, this embodiment provides the following technical solution: Please refer to Figure 1-3 As shown, the high-transmittance ultraviolet fluorescence detection lens 10 has a focal length of 25-30mm, a numerical aperture of 0.3-0.4, a distortion of ≤0.15%, and a total optical length of 60-70mm.

[0046] It should be noted that the focal length of 25-30mm is achieved through the power distribution of five lenses. The first lens 12 and the fourth lens 16 provide the main positive power, the second lens 13 and the fifth lens 17 provide negative power for correction, and the third lens 14 assists in correcting aberrations. The numerical aperture of 0.3-0.4 is determined by the ratio of the aperture stop 15 diameter to the focal length. This numerical aperture range can be achieved by using an aperture stop diameter of 3-4mm in combination with a focal length of 25-30mm. Distortion ≤0.15% is achieved through asymmetric lens configuration and aperture stop position optimization. Iterative optimization is performed using optical design software to ensure that distortion in each field of view is controlled within the allowable range. The total optical length of 60-70mm includes the thickness of the object plane protection window 11, the center thickness of the five lenses, the air gap, and the image plane distance. Miniaturization is achieved through a compact structural design. The lens barrel is CNC machined from aluminum alloy, and the inner wall is provided with extinction threads to reduce stray light.

[0047] Focal length determines the imaging magnification and working distance, numerical aperture determines the resolution and light-gathering ability, distortion affects measurement accuracy, and total optical length affects the system integration space.

[0048] With this implementation method, the high-transmittance ultraviolet fluorescence detection lens 10 has a moderate working distance, which is convenient for matching with the object being detected; the numerical aperture of 0.3-0.4 ensures sufficient resolution and signal strength; the distortion of ≤0.15% meets the requirements of precision detection and has small measurement error; the total optical length of 60-70mm is compact and easy to integrate into various detection equipment.

[0049] As an example, overall transmittance in the ultraviolet band is a core indicator for evaluating lens performance, and insufficient transmittance in existing technologies leads to severe signal attenuation. To address the aforementioned technical problems, this embodiment provides the following technical solution: Please refer to Figure 1-3 As shown, the high-transmittance ultraviolet fluorescence detection lens 10 has an overall transmittance of ≥88% in the 250nm-380nm band.

[0050] It should be noted that the overall transmittance is achieved through a combination of material selection, surface coating, and structural optimization. Calcium fluoride material has an intrinsic transmittance of ≥95% in the 250nm-380nm wavelength range, fused silica material has an intrinsic transmittance of ≥93%, and the cumulative transmittance of the five lens materials is approximately 85%. Combined with an anti-reflection coating with a single-sided transmittance of ≥92%, the cumulative transmittance loss across the ten working surfaces is controlled to within 10%. The inner wall of the lens barrel undergoes an extinction treatment to reduce internal reflection loss. The image plane protection window has a transmittance of ≥95%. After assembly, the overall transmittance is tested using a UV spectrophotometer, covering five characteristic points: 250nm, 280nm, 315nm, 350nm, and 380nm, ensuring a full-band transmittance of ≥88%.

[0051] High transmittance ensures that the fluorescence signal is minimized during transmission from the object plane to the image plane, thereby increasing the signal strength received by the detector.

[0052] After adopting this implementation method, the fluorescence signal attenuation is reduced by more than 50%, and the imaging brightness is significantly improved; weak fluorescence signals can also be effectively detected, and the detection sensitivity is improved; high transmittance reduces the requirements for light source power, reduces system energy consumption, and extends service life.

[0053] As an example, the optical parameters of a material determine the lens's chromatic aberration correction capability and transmission performance. In existing technologies, mismatched material parameters lead to image quality degradation. To address the aforementioned technical problems, this embodiment provides the following technical solution: Please refer to Figure 1-3 As shown, the refractive index of the calcium fluoride material is Nd=1.43 and the dispersion coefficient is Vd=95; the refractive index of the fused silica material is Nd=1.46 and the dispersion coefficient is Vd=67.8.

[0054] It should be noted that the calcium fluoride material is made of optical-grade CaF2 single crystal, prepared by the Czochralski method. The refractive index is measured at a wavelength of 546 nm using the minimum deviation angle method, and the dispersion coefficient is calculated by measuring the refractive index at multiple characteristic wavelengths. The fused silica material is made of JGS1 grade synthetic quartz, prepared by electrofusion, with impurity content controlled below 10 ppm. The refractive index difference between the two materials is 0.03, and the dispersion coefficient difference is 27.2, forming good dispersion complementary characteristics. The materials are annealed before processing to eliminate internal stress, and the surface shape accuracy after processing is controlled within λ / 4. The refractive index fluctuation between batches of materials is controlled within ±0.002 to ensure consistent lens performance. In practical applications, other ultraviolet transmitting materials with similar optical parameters can also be selected, but this application does not limit this.

[0055] The low refractive index and high dispersion coefficient of calcium fluoride, combined with the moderate refractive index and medium dispersion coefficient of fused silica, enable effective correction of axial chromatic aberration and magnification chromatic aberration through the combination of positive and negative lenses.

[0056] With this implementation method, the color difference correction effect in the ultraviolet band is significant, and the focusing position of light of different wavelengths is consistent; the stable material parameters ensure the consistency of lens performance in mass production; the cost of the two materials is controllable, making it suitable for large-scale applications.

[0057] As an example, the object surface protection window 11 needs to strike a balance between protecting the internal lens and ensuring ultraviolet transmission. In the prior art, an unreasonable design of the protection window affects optical performance. To address the above technical problems, this embodiment provides the following technical solution: Please refer to Figure 1-3 As shown, the thickness of the object surface protection window 11 is 2-5mm, which is used to protect the internal lens assembly and does not affect the transmission of ultraviolet light.

[0058] It should be noted that the object protection window 11 is made of calcium fluoride crystal material, with a thickness of 2-5mm, selected according to the usage scenario. Portable devices use a thinner window of 2-3mm to reduce weight, while fixed devices use a thicker window of 4-5mm to enhance protection. The window diameter is 2-3mm larger than the lens aperture to ensure unobstructed light across the entire field of view. Both sides are precision polished, with a surface roughness of less than 10nm and a surface shape accuracy of λ / 4. The edges are chamfered to prevent chipping, with a chamfer size of 0.2-0.3mm × 45°. The window is fixed to the front end of the lens barrel by a pressure ring made of stainless steel, with a clearance fit between the inner diameter and the outer diameter of the window, a fit tolerance of H7 / g6. An elastic washer is placed between the window and the pressure ring to buffer deformation caused by assembly stress and temperature changes.

[0059] As the frontmost component of the lens, the object protection window 11 is in direct contact with the external environment, blocking dust, liquids and physical contact from damaging the internal lens, while the calcium fluoride material ensures efficient transmission of ultraviolet light.

[0060] With this implementation method, the internal lens is reliably protected, and the service life of the high-transmittance ultraviolet fluorescence detection lens 10 is extended; the 2-5mm thickness minimizes light absorption loss while ensuring mechanical strength; the calcium fluoride material ensures that the object surface protection window 11 does not become a bottleneck for optical performance, and the overall transmittance is not affected.

[0061] As an example, the center thickness of each lens affects optical performance and mechanical strength. In existing technologies, unreasonable thickness design leads to poor aberration correction or lens fragility. To address these technical problems, this embodiment provides the following technical solution: Please refer to Figure 1-3 As shown, the center thickness of the first lens 12 is 3.5-4.5 mm, the center thickness of the second lens 13 is 2.0-3.0 mm, the center thickness of the third lens 14 is 2.5-4.0 mm, the center thickness of the fourth lens 16 is 3.0-4.0 mm, and the center thickness of the fifth lens 17 is 2.5-3.5 mm.

[0062] The first lens 12 has a center thickness of 3.5-4.5 mm and an edge thickness of not less than 1.5 mm, ensuring the mechanical strength and optical power requirements of the positive optical power biconvex lens. The second lens 13 has a center thickness of 2.0-3.0 mm and an edge thickness of not less than 1.0 mm; the thinner center of the negative optical power biconcave lens is beneficial for chromatic aberration correction. The third lens 14 has a center thickness of 2.5-4.0 mm; its meniscus structure has a moderate thickness, balancing aberration correction and manufacturing feasibility. The fourth lens 16 has a center thickness of 3.0-4.0 mm, close to the thickness of the first lens 12, providing the main converging optical power. The fifth lens 17 has a center thickness of 2.5-3.5 mm and an edge thickness of not less than 1.2 mm; this negative optical power meniscus lens is used for final aberration correction. The thickness tolerance of each lens is controlled within ±0.05 mm, achieved through precision grinding and polishing processes. Thickness is measured using a contact thickness gauge, and each lens undergoes a full inspection after processing.

[0063] The thickness at the center of a lens determines its optical power and light refraction ability, while also affecting its mechanical strength and manufacturing difficulty. A reasonable thickness distribution achieves a balance between optical performance and manufacturability.

[0064] With this implementation method, the optical power distribution of each lens is reasonable, and the aberration correction effect is optimal; the lens thickness meets the mechanical strength requirements, and it is not easily damaged during assembly and use; the thickness tolerance is strictly controlled, and the performance consistency of mass-produced lenses is high; the processing difficulty is moderate, and the production cost is controllable.

[0065] 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 high-transmittance ultraviolet fluorescence detection lens, characterized in that, The optical axis, from the object side to the image side, includes an object protection window (11), a first lens (12), a second lens (13), a third lens (14), an aperture stop (15), a fourth lens (16), a fifth lens (17), and an image plane (18). The surface protection window (11) is made of calcium fluoride material; In the first lens (12) to the fifth lens (17), at least some of the lenses are made of calcium fluoride material, and at least some of the lenses are made of fused silica material; The surfaces of the first lens (12) to the fifth lens (17) are coated with an ultraviolet anti-reflective film.

2. The high-transmittance ultraviolet fluorescence detection lens according to claim 1, characterized in that, The first lens (12) is a biconvex spherical lens with positive optical power and is made of calcium fluoride material; The second lens (13) is a negative optical power biconcave spherical lens made of fused silica material; The third lens (14) is a positive optical power curved moon lens, made of calcium fluoride material; The fourth lens (16) is a positive optical power biconvex spherical lens made of fused silica material; The fifth lens (17) is a negative optical power curved lunar surface lens, made of calcium fluoride material.

3. The high-transmittance ultraviolet fluorescence detection lens according to claim 1 or 2, characterized in that, The ultraviolet antireflective film has a multilayer structure, with a wavelength range of 250nm-380nm and a single-sided transmittance of ≥92%.

4. The high-transmittance ultraviolet fluorescence detection lens according to claim 1, characterized in that, The aperture stop (15) is disposed between the third lens (14) and the fourth lens (16), and the aperture of the aperture stop (15) is 3-4 mm.

5. The high-transmittance ultraviolet fluorescence detection lens according to claim 4, characterized in that, The aperture size of the aperture stop (15) can be adjusted according to the fluorescence intensity.

6. The high-transmittance ultraviolet fluorescence detection lens according to claim 1, characterized in that, The high-transmittance ultraviolet fluorescence detection lens (10) has a focal length of 25-30mm, a numerical aperture of 0.3-0.4, a distortion of ≤0.15%, and a total optical length of 60-70mm.

7. The high-transmittance ultraviolet fluorescence detection lens according to claim 1, characterized in that, The high-transmittance ultraviolet fluorescence detection lens (10) has an overall transmittance of ≥88% in the 250nm-380nm band.

8. The high-transmittance ultraviolet fluorescence detection lens according to claim 2, characterized in that, The calcium fluoride material has a refractive index of Nd=1.43 and a dispersion coefficient of Vd=95. The fused silica material has a refractive index of Nd=1.46 and a dispersion coefficient of Vd=67.

8.

9. The high-transmittance ultraviolet fluorescence detection lens according to claim 1, characterized in that, The thickness of the object surface protection window (11) is 2-5mm, which is used to protect the internal lens assembly and does not affect the transmission of ultraviolet light.

10. The high-transmittance ultraviolet fluorescence detection lens according to claim 2, characterized in that, The center thickness of the first lens (12) is 3.5-4.5 mm, the center thickness of the second lens (13) is 2.0-3.0 mm, the center thickness of the third lens (14) is 2.5-4.0 mm, the center thickness of the fourth lens (16) is 3.0-4.0 mm, and the center thickness of the fifth lens (17) is 2.5-3.5 mm.

Images