Low-heat-effect radiation-proof alarm optical lens

Abstract

The invention provides a low-heat-effect anti-radiation alarm optical lens. The low-heat-effect anti-radiation alarm optical lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged from the object side to the image side in the light path direction. Wherein the first lens is a meniscus lens made of a quartz material, the second lens is a meniscus lens made of a radiation-resistant optical material, the third lens is a meniscus lens made of an HZF62 material, the fourth lens is a biconvex lens made of an HLaK53 material, the fifth lens is a meniscus lens made of an HLaK53 material, and the sixth lens is a plano-convex lens made of an HK9L material. The working wave band of the lens is 0.4-1.1 [mu] m, the field of view of a linear region is 180 degrees, and the proportion of a four-quadrant difference algorithm of an edge field of view is not lower than 0.89. According to the lens, the proportion of a four-quadrant difference algorithm is 0.89; the wave band is designed to cover 0.4-1.1 [mu] m, strong light signals are identified and protected in a full-passband, and the use requirements of the laser alarm lens are met; the antenna has space radiation resistance, is low in heat effect, and is suitable for a satellite system.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of optical system design, and in particular to a low-heat-effect anti-radiation warning optical lens. BACKGROUND

[0002] A satellite laser warning lens is usually matched with a four-quadrant detector to transmit laser energy in different fields of view to the detector by detecting laser signals emitted by a target. A calculation program reads energy values in different quadrants, calculates a four-quadrant energy ratio by using a differential algorithm, and outputs target position coordinates according to a pre-stored relationship between the energy ratio and the light incidence angle to realize the warning function. Different from a traditional four-quadrant laser semi-active lens with a large field of view, the laser warning lens in this application does not focus on the spot size, but focuses on the four-quadrant energy ratio. Meanwhile, different from an ordinary laser semi-active homing system, the special application environment of a satellite system requires that the satellite optical lens has anti-radiation capability.

[0003] As the core part of a laser warning system, the performance of an optical lens usually affects the ability of the lens to search and track a target, and more importantly, directly affects the accuracy of the target direction detected by the lens. From the perspective of target defense capability, the larger the instantaneous field of view of the optical lens is, the better. The energy distribution of a target at each angle formed by the optical lens should be uniform, and the four-quadrant energy distribution should meet a certain proportional relationship. In order to improve the anti-interference capability of the optical lens, light-absorbing threads are added inside the lens to weaken or eliminate the influence of background light and stray light on the target direction detection accuracy.

[0004] Most of the lenses of this type found abroad adopt a catadioptric optical structure, and the instantaneous field of view that can be achieved by this type of lens is generally less than 2°. In addition, catadioptric lenses generally have problems such as difficult machining and assembly. Most of the lenses of this type found in China are refractive optical lenses, but the linear field of view (2ω) is generally less than 25°. The lenses with a linear field of view greater than 25° pay more attention to the size of the diffraction spot in the design process, and the spot size is usually half of the detector, which leads to an exponential relationship between the four-quadrant energy ratio of the optical lens and the angle. As the angle increases, the angle measurement accuracy of the optical lens decreases significantly. In addition, most of the lenses of this type found in China are single-wavelength lenses, which can only prevent damage caused by strong laser of a specific wavelength. SUMMARY

[0005] In view of the above defects or deficiencies in the prior art, the application aims to provide a low-heat-effect anti-radiation warning optical lens, which comprises: A first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens are sequentially arranged along the light path direction from the object side to the image side. The first lens is a meniscus lens made of quartz material, the second lens is a meniscus lens made of radiation-resistant optical material, the third lens is a meniscus lens made of HZF62 material, the fourth lens is a double-convex lens made of HLaK53 material, the fifth lens is a meniscus lens made of HLaK53 material, and the sixth lens is a plano-convex lens made of HK9L material. The working waveband of the lens is 0.4-1.1 μm, the linear region field of view is 180°, and the four-quadrant differential algorithm ratio of the edge field of view is not less than 0.89.

[0006] According to the technical scheme provided in the embodiments of the present application, the front surface radius of the first lens is 45-50 mm, the rear surface radius is 5-10 mm, the front surface light aperture is φ25-φ32 mm, the rear surface light aperture is φ12-φ17 mm, and the thickness is 2-4 mm; the front surface radius of the second lens is 18-23 mm, the rear surface radius is 3-6 mm, the front surface light aperture is φ9-φ13 mm, the rear surface light aperture is φ6-φ9 mm, and the thickness is 1-3 mm.

[0007] According to the technical scheme provided in the embodiments of the present application, the front surface radius of the third lens is 3-6 mm, the rear surface radius is 2-5 mm, the front surface light aperture is φ3-φ6 mm, the rear surface light aperture is φ2-φ5 mm, and the thickness is 1-3 mm; the front surface radius of the fourth lens is 25-30 mm, the rear surface radius is 5-9 mm, the front surface light aperture is φ2-φ6 mm, the rear surface light aperture is φ2-φ6 mm, and the thickness is 1-3 mm.

[0008] According to the technical scheme provided in the embodiments of the present application, the front surface radius of the fifth lens is 4-8 mm, the rear surface radius is 12-17 mm, the front surface light aperture is φ3-φ7 mm, the rear surface light aperture is φ3-φ6 mm, and the thickness is 1-3 mm; the front surface radius of the sixth lens is 2-6 mm, the rear surface radius is 100 mm to a plane, the front surface light aperture is φ4-φ7 mm, the rear surface light aperture is φ4-φ6 mm, and the thickness is 1-3 mm.

[0009] According to the technical scheme provided in the embodiment of the application, the distance between the first lens and the second lens is 2mm-4mm; the distance between the second lens and the third lens is 1mm-3mm; the distance between the third lens and the fourth lens is 2mm-5mm; the distance between the fourth lens and the fifth lens is 0.2mm-2mm; and the distance between the fifth lens and the sixth lens is 1mm-3mm.

[0010] According to the technical scheme provided in the embodiment of the application, at least one surface of the lens is provided with a metal coating film; the surface is at least one of the light-incident front surface of the lens barrel, the light-incident surface of the pressing ring of the first lens, the lens barrel plane in contact with the rear surface of the first lens, and the light-incident surface of the pressing ring of the second lens.

[0011] According to the technical scheme provided in the embodiment of the application, the metal film is a gold film.

[0012] According to the technical scheme provided in the embodiment of the application, the working temperature range of the lens is-35℃-70℃.

[0013] According to the technical scheme provided in the embodiment of the application, the lens is configured to be used in matching with a four-quadrant detector, and the four-quadrant differential energy ratio is calculated by the following formula to determine the incident light angle: ((area 1 energy+area 2 energy)-(area 3 energy+area 4 energy)) / (area 1 energy+area 2 energy+area 3 energy+area 4 energy) Wherein, the area 1 to area 4 are four quadrants divided by the image plane of the four-quadrant detector according to the rectangular coordinates.

[0014] According to the technical scheme provided in the embodiment of the application, the inner wall of the lens barrel of the lens is provided with an extinction thread.

[0015] Compared with the prior art, the application has the following beneficial effects: I. Achieving super-wide linear field of view and high-precision angle measurement: through the unique six-lens structure (quartz-radiation-resistant K709-HZF62-HLaK53-HLaK53-HK9L) and the optimization of optical power distribution, the linear field of view (2ω) is successfully expanded to 180°, overcoming the technical bottlenecks of small field of view (<2°) of catadioptric structure, difficult assembly and adjustment, and narrow linear field of view (usually <25°) of domestic refractive lenses. At the same time, by strictly controlling the energy distribution of the light spot through optical design, the proportion of the four-quadrant differential algorithm of the edge field of view is ensured to be not less than 0.89, so that the angle measurement response in the full field of view is approximately linear, effectively avoiding the problem of rapid decline of angle measurement precision caused by exponential effect in the prior art under large field of view, and realizing consistent high-precision angle detection in a super-large field of view.

[0016] II. Wide-band anti-strong laser damage and spatial anti-radiation capability: The working waveband of the lens covers a wide spectrum of 0.4-1.1 μm, and can identify and protect various strong laser signals of multiple wavelengths within the passband. The lens breaks through the defect of limited protection range of most domestic single-wavelength lenses. In particular, the front end of the lens is made of special optical materials such as quartz and radiation-resistant K709, and combined with gold plating treatment of the key light-accepting surface and other processes, the lens has low thermal effect and high anti-radiation performance, and can meet the harsh requirements of satellite and other on-orbit platforms on the long-term and reliable operation of optical lenses in strong laser and space radiation harsh environments.

[0017] III. Optimized system performance and volume: The present application adopts a total refraction type structure, avoiding the processing and adjustment difficulties of the catadioptric system, which is beneficial to engineering implementation. While realizing 180° super-wide field of view and wide-band working capability, through the fine design of lens parameters and spacing, the miniaturization and compactness of the lens are ensured, the energy distribution of the light spot is uniform, the differential algorithm requirements of the four-quadrant detector are perfectly matched, and the overall performance, environmental adaptability and reliability of the laser warning system are significantly improved.

[0018] In summary, the lens of this application adopts a refractive optical lens form, the linear area field of view (2ω) reaches 180°, combined with the volume requirement of the lens, the aperture weight and field of view weight are reasonably distributed, the four-quadrant differential algorithm ratio is 0.89; the design waveband covers 0.4-1.1 μm, which can realize strong light signal identification and protection within the full passband, and meet the requirements of laser warning lens; it has spatial anti-radiation performance, low thermal effect, and is suitable for satellite systems. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The structure schematic diagram of the low-thermal-effect anti-radiation warning optical lens provided by the embodiment of the present application; Figure 2 The special treatment surface schematic diagram of the low-thermal-effect anti-radiation warning optical lens provided by the embodiment of the present application for reducing thermal effect; Figure 3 The four-quadrant detector image surface partition schematic diagram of the low-thermal-effect anti-radiation warning optical lens provided by the embodiment of the present application for use together; Figure 4 The imaging light spot column diagram of the low-thermal-effect anti-radiation warning optical lens provided by the embodiment of the present application at different field points at 20°C; Figure 5 The imaging light spot column diagram of the low-thermal-effect anti-radiation warning optical lens provided by the embodiment of the present application at different field points at-35°C; Figure 6 The imaging light spot column diagram of the low-thermal-effect anti-radiation warning optical lens provided by the embodiment of the present application at different field points at 70°C; Figure 7 A spot energy distribution diagram of the low-heat-effect anti-radiation warning optical lens provided by the embodiment of the present application under a typical field of view is shown in the following table: Figure 8 A four-quadrant differential algorithm energy ratio curve of the low-heat-effect anti-radiation warning optical lens provided by the embodiment of the present application in the field of view of 0°-55° (2ω: 0°-110°) is shown in the following table.

[0020] The text annotations in the figure represent: 1, first lens; 2, second lens; 3, third lens; 4, fourth lens; 5, fifth lens; 6, sixth lens; 7, front light-accepting surface of the lens barrel; 8, front light-accepting surface of the compression ring of the first lens; 9, lens barrel plane contacting the rear surface of the first lens; 10, front light-accepting surface of the compression ring of the second lens. DETAILED DESCRIPTION

[0021] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely intended for the purpose of interpretation of the related application, and not for the limitation of the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for ease of description.

[0022] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and embodiments.

[0023] Embodiment 1 As mentioned in the background, in order to solve the problems in the prior art, the present application provides a low-heat-effect anti-radiation warning optical lens, as shown in Figure 1 which comprises: a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5 and a sixth lens 6 arranged in sequence along the optical path direction from the object side to the image side; The first lens 1 is a meniscus lens made of quartz material, the second lens 2 is a meniscus lens made of radiation-resistant optical material, the third lens 3 is a meniscus lens made of HZF62 material, the fourth lens 4 is a double-convex lens made of HLaK53 material, the fifth lens 5 is a meniscus lens made of HLaK53 material, and the sixth lens 6 is a plano-convex lens made of HK9L material. The working waveband of the lens is 0.4 μm-1.1 μm, the linear region field of view is 180°, and the four-quadrant differential algorithm ratio of the edge field of view is not less than 0.89.

[0024] Specifically, low thermal effect: refers to the optical lens when receiving and transmitting strong laser signals, the temperature rise caused by its own absorption of light energy or other reasons is small, so as to avoid the problems of focus shift, image quality degradation caused by thermal expansion, refractive index change (dn / dt). This is achieved through material selection, structure design and surface treatment. Anti-radiation: refers to the lens in the space and other environments with high-energy particle (such as gamma ray, electron, proton) radiation, the transmittance of the optical material (mainly glass) will not decrease significantly (i.e. darkening or coloring), and the optical performance remains stable. This is mainly achieved by selecting radiation-resistant optical materials. Warning optical lens refers to the function of the lens is not imaging, but for detecting specific waveband (here 0.4μm ~1.1μm) laser signal, and through the subsequent photodetector (such as four-quadrant detector) and algorithm, determine the direction of the incoming laser, realize the early warning. From the object side to the image side: defines the direction of light propagation. The object side is the side where the target (incoming laser) is located, and the image side is the side where the light converges after passing through the lens and the detector. Meniscus lens, double convex lens, plano-convex lens: are the classification of lens shape. Meniscus lens is convex on one side and concave on the other side, like a crescent moon; double convex lens is convex on both sides; plano-convex lens is flat on one side and convex on the other side. These shape combinations are used to control the deflection of light and correct various aberrations.

[0025] Specifically, quartz material, radiation-resistant optical material, HZF62, HLaK53, HK9L: these are the specific optical glass or crystal material brand or general name. Quartz (such as fused quartz) has extremely low thermal expansion coefficient and excellent ultraviolet to near-infrared transmittance; radiation-resistant optical material (such as K709) is a specially treated glass that can resist radiation-induced darkening; HZF62, HLaK53, HK9L are domestic optical glass brands with specific refractive index and Abbe number to meet the needs of aberration correction and chromatic aberration control.

[0026] Specifically, linear field of view is 180° (2ω): refers to within this full angle of view, the incident light angle and the calculated differential energy ratio on the detector maintain a good linear relationship. This is the key to achieving high-precision angle measurement, avoiding the dramatic increase in measurement error caused by nonlinear or exponential relationship.

[0027] Specifically, the ratio of four-quadrant differential algorithm is not less than 0.89: this is a specific quantitative indicator to measure linearity. At the maximum field of view (edge of field, i.e. 90° half field of view), the energy ratio calculated by a specific algorithm reaches 0.89, indicating excellent linearity within the entire 180° field of view.

[0028] The implementation process is described as follows: mainly includes optical design, material procurement, lens processing, coating and adjustment: Optical design: Use professional optical design software such as Zemax, Code V, etc. to establish the initial six-lens structure. Arrange the first lens 1 to the sixth lens 6 in order, and specify their materials as quartz, radiation-resistant K709, HZF62, HLaK53, HLaK53, and HK9L respectively. Set the optimization target, including the working waveband 0.4-1.1 μm, the full field angle 180°, and strictly control the spot diagram size and the energy distribution of the light spot to ensure that the differential ratio of the edge field of view reaches more than 0.89. Through repeated optimization, determine the optimal range of parameters such as the curvature radius, thickness, and spacing of each lens.

[0029] Material preparation and lens processing: According to the design results, purchase optical materials that meet the specifications. Then use precision optical cold processing techniques such as fine grinding and polishing to process the materials into lenses with specified curvature radii, center thicknesses, and clear apertures. It is necessary to ensure that the surface accuracy (such as the number of circles, local error) and surface finish meet the requirements.

[0030] Coating: Coating anti-reflection films on all lens surfaces to increase the transmittance in the 0.4-1.1 μm waveband and reduce reflection loss.

[0031] Barrel processing and adjustment: Design and process the barrel, and internally machine the light extinction threads. Accurately assemble the processed lenses into the barrel in order and with a determined air gap, and ensure the concentricity of the optical axes of each lens. This process requires high-precision centering and assembly technology.

[0032] This embodiment realizes ultra-wide field of view and high linearity: It realizes a linear area field of view of 180°, far exceeding the foreign catadioptric structure (<2°) and domestic refractive lens (usually <25°) mentioned in the background art. The differential ratio of 0.89 at the edge field of view ensures the consistency of the measurement angle accuracy in the entire ultra-wide field of view, avoiding the problem of rapid decrease in accuracy at large angles in the prior art. Wide waveband operation and damage resistance: Covering a wide waveband of 0.4-1.1 μm, it can cope with laser threats of multiple wavelengths and overcome the limitations of single-wavelength lenses. The use of quartz and radiation-resistant materials at the front end improves the ability to resist laser damage and space radiation. Environmental adaptability: The unique material combination and structural design endow the lens with low thermal effect, making it stable in performance under temperature changes (-35℃~70℃). Structural feasibility and miniaturization: Compared with catadioptric structures, the all-refractive structure is easier to process and assemble, and at the same time, through optimization, the system is miniaturized.

[0033] The core principle underlying this embodiment is to achieve aberration correction and specific energy distribution under ultra-wide field of view through synergistic optimization of material combination and power distribution. The six lenses constitute a complex optical system. The first quartz lens is a key anti-radiation barrier; the second radiation-resistant lens further improves this performance; the subsequent lens combinations of HZF62, HLaK53, etc. effectively correct spherical aberration, coma, astigmatism, field curvature, and especially chromatic aberration under a wide wavelength band, by virtue of their different refractive indices and dispersion characteristics. The sixth plano-convex lens 6 helps the light rays to converge on the detector at a suitable angle. Ultimately, this design makes the parallel light incident at different angles form a spot on the focal plane (four-quadrant detector) after passing through the system, with the center position of the energy distribution being highly linearly related to the incident angle, so as to accurately calculate the angle by a differential algorithm. Controlling the energy ratio of the edge field to be above 0.89 is a direct manifestation of the ideal state of aberration balance in the optimization process.

[0034] In a preferred embodiment, the front surface radius of the first lens 1 is 45-50 mm, the back surface radius is 5-10 mm, the front surface clear aperture is φ25-φ32 mm, the back surface clear aperture is φ12-φ17 mm, and the thickness is 2-4 mm; the front surface radius of the second lens 2 is 18-23 mm, the back surface radius is 3-6 mm, the front surface clear aperture is φ9-φ13 mm, the back surface clear aperture is φ6-φ9 mm, and the thickness is 1-3 mm.

[0035] Specifically, the front surface radius and the back surface radius refer to the curvature radius values of the two optical surfaces of the lens. A positive value usually indicates that the surface protrudes towards the object side, and a negative value indicates that the surface is concave (the specific symbol convention needs to be based on the drawing or description). These radius values directly determine the power (focal length) and aberration contribution of the lens. The clear aperture refers to the effective aperture diameter actually used by the light to pass through the lens, which is usually smaller than the physical outer diameter of the lens. It limits the size of the light beam and affects the relative aperture and vignetting of the system. The thickness refers to the central thickness of the lens on the optical axis, which affects the optical path length and aberration.

[0036] Specifically, the first lens 1 is processed as follows: a quartz material blank is used, and precise machining is performed to ensure that the front surface radius is controlled between 45 mm and 50 mm (which can be detected by a spherometer or an interferometer, for example), and the back surface radius is controlled between 5 mm and 10 mm. The central thickness of the lens is processed to be between 2 mm and 4 mm. The clear aperture of the front surface is processed to be φ25-φ32 mm, and the clear aperture of the back surface is φ12-φ17 mm. This usually means that the edges of the lens need to be ground according to the aperture.

[0037] Second lens 2 processing: using radiation-resistant K709 material blank, processing its front surface radius to 18mm to 23mm, back surface radius to 3mm to 6mm. The center thickness is controlled at 1mm to 3mm. The front surface clear aperture is φ9mm to φ13mm, and the back surface clear aperture is φ6mm to φ9mm.

[0038] Precision control: during processing, the tolerances of curvature radius, thickness and aperture need to be strictly controlled, usually to micron level precision, to ensure that the optical performance is consistent with the design expectation. Each lens after processing needs to be strictly detected.

[0039] Specifically, the first lens 1 acts as a "window" of the system, its larger front surface radius and clear aperture help to receive light within a 180° large field of view, while the quartz material ensures thermal stability and front-end laser damage resistance. Its specific meniscus shape (radius positive negative) helps to correct the astigmatism and field curvature brought by the large field of view. Introducing anti-radiation characteristics and participating in aberration correction: the second lens 2 uses radiation-resistant material to further improve performance. Its smaller size and specific curvature, in cooperation with the first lens 1, begin to converge the light beam and perform preliminary aberration correction, preparing for the more intense power transformation later. Accurate control of the parameters of the two lenses is the premise of balancing the large field of view of the incident light, controlling the primary aberrations (such as spherical aberration, coma), and managing the total length of the system. Ensure spot quality: if the parameters of the first two lenses deviate from the range described, it may cause large-angle light to fail to enter the system smoothly, or introduce too much distortion and aberration, causing the energy distribution of the spot on the detector to deviate from the ideal linear relationship, and unable to meet the 0.89 differential ratio requirement of the edge field of view.

[0040] In a preferred embodiment, the front surface radius of the third lens 3 is 3mm to 6mm, the back surface radius is 2mm to 5mm, the front surface clear aperture is φ3mm to φ6mm, the back surface clear aperture is φ2mm to φ5mm, and the thickness is 1mm to 3mm; the front surface radius of the fourth lens 4 is 25mm to 30mm, the back surface radius is 5mm to 9mm, the front surface clear aperture is φ2mm to φ6mm, the back surface clear aperture is φ2mm to φ6mm, and the thickness is 1mm to 3mm.

[0041] Specifically, the third lens 3 is processed: using HZF62 material blank. Its front surface radius is precisely processed to 3mm to 6mm, and the back surface radius is processed to 2mm to 5mm. The center thickness of the lens is controlled at 1mm to 3mm. The front surface clear aperture is φ3mm to φ6mm, and the back surface clear aperture is φ2mm to φ5mm. HZF62 is usually a heavy flint glass with high refractive index and relatively high dispersion, which is crucial for correcting chromatic aberration.

[0042] Specifically, the fourth lens 4 is processed: using a HLaK53 material blank. Its front surface radius is processed to 25mm to 30mm, and the back surface radius is processed to 5mm to 9mm. The center thickness is controlled to 1mm to 3mm. The clear aperture of the front and back surfaces is processed to φ2mm to φ6mm. HLaK53 is usually a lanthanum crown glass with high refractive index and low dispersion characteristics. It is worth noting that the fourth lens 4 is a biconvex lens, both sides are convex, and the optical power is positive and strong.

[0043] The embodiment realizes strong optical power and aberration correction core: the third lens 3 and the fourth lens 4 constitute a key “optical power group” in the system, especially the biconvex fourth lens 4, which usually undertakes the main positive optical power of the system. They will strongly converge the light beams from the front lens. Chromatic aberration correction key: the material combination of the third lens 3 (HZF62, high dispersion) and the fourth lens 4 (HLaK53, low dispersion) is the core of correcting the axial chromatic aberration (different focal point positions of light rays of different wavelengths) and the magnification chromatic aberration (different imaging heights of light rays of different wavelengths). The combination of such “positive-negative” dispersion materials is a classic method of achromatization. Control advanced aberrations: the specific curvature and thickness of the two lenses are carefully optimized to control advanced quantities of spherical aberration (such as edge spherical aberration) and coma, etc., to ensure that the light spot energy is concentrated and the shape is symmetrical.

[0044] In a preferred embodiment, the front surface radius of the fifth lens 5 is 4mm to 8mm, the back surface radius is 12mm to 17mm, the front surface clear aperture is φ3mm to φ7mm, the back surface clear aperture is φ3mm to φ6mm, and the thickness is 1mm to 3mm; the front surface radius of the sixth lens 6 is 2mm to 6mm, the back surface radius is 100mm to plane, the front surface clear aperture is φ4mm to φ7mm, the back surface clear aperture is φ4mm to φ6mm, and the thickness is 1mm to 3mm.

[0045] Specifically, the back surface radius is 100mm to plane: it means that the back surface curvature radius of the sixth lens 6 can be from 100mm (very gentle convex) to infinity (i.e. a real plane). This allows the selection of the most easily processed surface type under the premise of ensuring performance.

[0046] Specifically, the fifth lens 5 is processed: using a HLaK53 material blank (the same material as the fourth lens 4, but different in shape and function). Its front surface radius is processed to 4mm to 8mm, and the back surface radius is processed to 12mm to 17mm. The center thickness is controlled to 1mm to 3mm. The front surface clear aperture is φ3mm to φ7mm, and the back surface clear aperture is φ3mm to φ6mm. The fifth lens 5 is a meniscus lens.

[0047] Specifically, the sixth lens 6 is processed: using HK9L material blank. Its front surface radius is processed to 2mm to 6mm, and the back surface is selected according to the design, processed into a large curvature convex surface with a radius greater than or equal to 100mm or a plane. The center thickness is controlled to be 1mm to 3mm. The front surface clear aperture is φ4mm to φ7mm, and the back surface clear aperture is φ4mm to φ6mm. The sixth lens 6 is a plano-convex lens.

[0048] The embodiment realizes the final balance of image plane flatness and aberration: the fifth lens 5 (meniscus) is usually used to further correct astigmatism and field curvature, and ensure that the light spot is clearly focused on the same plane of the detector within the entire 180° field of view (i.e. image plane flatness). Control the incident angle of light: the sixth lens 6 (plano-convex) as the last piece of lens, one of its core functions is to control the chief ray to be incident at a near vertical angle to the four-quadrant detector surface. This is crucial to ensure that the energy received by each quadrant accurately reflects the center position of the light spot, and if the incident angle is too large, unnecessary errors will be introduced. System back working distance management: the design of the last two lenses determines the distance from the last surface of the lens to the detector image plane (back working distance), which needs to reserve space for the installation of the detector. The parameter range ensures a reasonable back working distance.

[0049] In a preferred embodiment, the distance between the first lens 1 and the second lens 2 is 2mm to 4mm; the distance between the second lens 2 and the third lens 3 is 1mm to 3mm; the distance between the third lens 3 and the fourth lens 4 is 2mm to 5mm; the distance between the fourth lens 4 and the fifth lens 5 is 0.2mm to 2mm; the distance between the fifth lens 5 and the sixth lens 6 is 1mm to 3mm.

[0050] Specifically, the distance between them refers to the air gap between the back surface vertex of the previous lens and the front surface vertex of the next lens in the direction of the optical axis. This distance is the physical space formed after the lens is fixed by mechanical structure (such as spacer) in the lens barrel.

[0051] Specifically, the barrel and spacer design: according to the final air gap value determined by the optical design file, the internal structure of the barrel is designed. The spacer needs to be precisely machined or the step inside the barrel is used to position each lens. For example, the gap between the first lens 1 and the second lens 2 (2mm ~ 4mm) needs to be guaranteed by a spacer with a thickness strictly controlled within this range. High-precision assembly: the lenses and spacers are sequentially assembled into the barrel. This process needs to be carried out in a clean environment, using high-precision length measuring instruments (such as micrometer, laser range finder) to cooperate with the assembly equipment, to ensure that after each lens is installed in place, the air gap between them strictly meets the design requirements. For example, the gap between the second lens 2 and the third lens 3 needs to be controlled between 1mm ~ 3mm, and the gap between the fourth lens 4 and the fifth lens 5 is very small (0.2mm ~ 2mm), which may require very thin spacers or precise barrel step design, and extra care is needed to ensure that the lenses do not touch. Fixing and verification: after all the lenses and spacers are installed, the lens group is reliably pressed and fixed by mechanical parts such as a compression ring to prevent displacement in environments such as vibration and impact. After assembly is completed, the optical performance of the entire optical system (such as focal length, MTF, spot diagram, etc.) needs to be verified again to indirectly confirm the accuracy of the spacing.

[0052] In a preferred embodiment, at least one surface of the lens is provided with a metal coating; the surface is at least one of the front light-incident surface 7 of the barrel, the compression ring light-incident surface 8 of the first lens 1, the barrel plane 9 in contact with the rear surface of the first lens 1, and the compression ring light-incident surface 10 of the second lens 2.

[0053] In a preferred embodiment, the metal film is a gold film.

[0054] Specifically, the implementation process is: surface preparation: thoroughly clean the lens surfaces, compression ring end faces and barrel inner side planes that need to be coated, to ensure that there are no contaminants, grease and dust, to ensure the adhesion of the coating.

[0055] Preferably, the metal film is a gold film, which has the highest reflectivity (up to 98% ~ 99%) among all metals in the near-infrared band above 0.7μm, and is very suitable for the working wavelength band of 0.4μm ~ 1.1μm, especially for common laser wavelengths such as 1.06μm. Excellent chemical stability: gold is an inert metal and is not easily oxidized or corroded, and can maintain stable performance in complex environments such as space for a long time, and will not cause a decrease in reflectivity due to surface oxidation. Good ductility and adhesion: gold film can form a dense and uniform film, and has good adhesion to glass and metal substrates.

[0056] In a preferred embodiment, the working temperature range of the lens is -35℃ ~ 70℃.

[0057] In a preferred embodiment, the lens is configured to be used with a four-quadrant detector, and the four-quadrant differential energy ratio is calculated by the following formula to determine the incident light angle: ((Area 1 energy + Area 2 energy) - (Area 3 energy + Area 4 energy)) / (Area 1 energy + Area 2 energy + Area 3 energy + Area 4 energy) Wherein, Area 1 to Area 4 are four quadrants of the four-quadrant detector image plane divided by the rectangular coordinates.

[0058] In a preferred embodiment, the inner wall of the lens barrel of the lens is provided with a light extinction thread.

[0059] The currently achievable technical performance of the present application is: linear field of view (2ω) 180°, focal length 0.9mm, working waveband 0.4μm~1.1μm, edge field of view four-quadrant differential algorithm ratio 0.89, working temperature range -35℃~70℃.

[0060] Specifically, Figure 2 It is a schematic diagram of a special treatment surface of a low-heat-effect anti-radiation warning optical lens. Since the optical lens receives and detects the strong light signal of a non-cooperative target, in order to reduce the heat effect of the optical lens and improve the survivability of the optical lens in a strong laser environment, a special surface treatment method is adopted for the surface of a specific position: the front light-accepting surface 7 of the lens barrel is treated by gold plating; the light-accepting surface of the first lens 1 compression ring is treated by gold plating; the lens barrel plane in contact with the rear surface of the first lens 1 is treated by gold plating; the light-accepting surface of the second lens 2 compression ring is treated by gold plating.

[0061] Figure 3 It is a schematic diagram of the partition of the image plane of the four-quadrant detector. According to the defined areas, a differential algorithm is used to evaluate the linearity of the laser warning lens, and the differential algorithm is specifically: ((Area 1 + Area 2) - (Area 3 + Area 4)) / (Area 1 + Area 2 + Area 3 + Area 4).

[0062] Figures 4-6 It is an imaging spot column diagram of a best embodiment of a low-heat-effect anti-radiation warning optical lens simulated by Zemax optical design software. The design input is wavelength 0.4 ~1.1 , half field of view 0°, 10°, 20°, 30°, 40°, 50° and 55°. Since the image quality of the positive direction field of view and the negative direction field of view is the same, only the positive direction field of view is taken when inputting. Figures 3-5 It can be seen that the imaging spot size of the optical lens at each temperature is uniform.

[0063] Figure 7Figure 1 is a low-heat-effect anti-radiation warning optical lens best embodiment imaging spot energy distribution diagram simulated by Lighttools optical analysis software, simulation input wavelength 0.4 ~1.1 , input half field of view 0°, 15°, 30°, 45°, 60° and 90°. Since the image quality of the positive direction field of view and the negative direction field of view is the same, only the positive direction field of view is taken when inputting. Figure 7 It can be seen that the imaging spot of the optical lens of the best embodiment can maintain a circular spot without obvious stray light at each field of view.

[0064] Figure 8 Figure 2 is a low-heat-effect anti-radiation warning optical lens best embodiment full-angle four-quadrant differential algorithm ratio curve diagram simulated by Lighttools optical analysis software and data processing software, and the four-quadrant differential algorithm is calculated by using a differential algorithm. Figure 8 It can be seen that the four-quadrant differential algorithm of the optical lens of the best embodiment has no inversion in the full field of view range, the ratio changes with the angle in an approximately linear trend, and has no exponential effect.

[0065] Table 1 is a specific simulation analysis numerical value of the four-quadrant differential energy ratio distribution of a low-heat-effect anti-radiation warning optical lens best embodiment at each angle by using Lighttools optical analysis software and data processing software.

[0066] The data in Table 1 shows that the low-heat-effect anti-radiation warning optical lens best embodiment is basically linear in the full-angle range, has no exponential effect, has consistent angle measurement accuracy in the full field of view range, and meets the use requirements of the differential algorithm for the optical lens.

[0067]

[0068] The principles and implementation modes of the present application are described in the specific examples in this paper, and the above example descriptions are only used to help understand the method and its core idea. The above description is only the preferred embodiment of the present application, and it should be pointed out that due to the limited nature of the language expression, there are infinitely many specific structures, and for ordinary technical personnel in this technical field, without departing from the principles of the present application, some improvements, refinements or changes can be made, and the above technical features can be combined in an appropriate manner; these improvements, refinements, changes or combinations, or the application of the inventive concept and technical solution to other occasions without improvement, shall be regarded as the protection scope of the present application.

Claims

1. A low-heat-effect radiation-resistant warning optical lens, characterized in that, include: The first lens (1), the second lens (2), the third lens (3), the fourth lens (4), the fifth lens (5) and the sixth lens (6) are arranged sequentially from the object side to the image side along the optical path. Among them, the first lens (1) is a meniscus lens made of quartz material, the second lens (2) is a meniscus lens made of radiation-resistant optical material, the third lens (3) is a meniscus lens made of HZF62 material, the fourth lens (4) is a biconvex lens made of HLaK53 material, the fifth lens (5) is a meniscus lens made of HLaK53 material, and the sixth lens (6) is a planoconvex lens made of HK9L material; The lens operates in the wavelength range of 0.4μm to 1.1μm, has a linear field of view of 180°, and the ratio of the four-quadrant difference algorithm for the edge field of view is not less than 0.

89.

2. The low-thermal-effect radiation-resistant alarm optical lens according to claim 1, characterized in that: The first lens (1) has a front surface radius of 45mm to 50mm, a rear surface radius of 5mm to 10mm, a front surface aperture of φ25mm to φ32mm, a rear surface aperture of φ12mm to φ17mm, and a thickness of 2mm to 4mm; the second lens (2) has a front surface radius of 18mm to 23mm, a rear surface radius of 3mm to 6mm, a front surface aperture of φ9mm to φ13mm, a rear surface aperture of φ6mm to φ9mm, and a thickness of 1mm to 3mm.

3. The low-thermal-effect radiation-resistant alarm optical lens according to claim 1, characterized in that: The third lens (3) has a front surface radius of 3mm to 6mm, a rear surface radius of 2mm to 5mm, a front surface aperture of φ3mm to φ6mm, a rear surface aperture of φ2mm to φ5mm, and a thickness of 1mm to 3mm; the fourth lens (4) has a front surface radius of 25mm to 30mm, a rear surface radius of 5mm to 9mm, a front surface aperture of φ2mm to φ6mm, a rear surface aperture of φ2mm to φ6mm, and a thickness of 1mm to 3mm.

4. The low-thermal-effect radiation-resistant alarm optical lens according to claim 1, characterized in that: The fifth lens (5) has a front surface radius of 4mm to 8mm, a rear surface radius of 12mm to 17mm, a front surface aperture of φ3mm to φ7mm, a rear surface aperture of φ3mm to φ6mm, and a thickness of 1mm to 3mm; the sixth lens (6) has a front surface radius of 2mm to 6mm, a rear surface radius of 100mm to the plane, a front surface aperture of φ4mm to φ7mm, a rear surface aperture of φ4mm to φ6mm, and a thickness of 1mm to 3mm.

5. The low-thermal-effect radiation-resistant alarm optical lens according to claim 1, characterized in that: The distance between the first lens (1) and the second lens (2) is 2mm to 4mm; the distance between the second lens (2) and the third lens (3) is 1mm to 3mm; the distance between the third lens (3) and the fourth lens (4) is 2mm to 5mm; the distance between the fourth lens (4) and the fifth lens (5) is 0.2mm to 2mm; and the distance between the fifth lens (5) and the sixth lens (6) is 1mm to 3mm.

6. The low-thermal-effect radiation-resistant alarm optical lens according to claim 1, characterized in that: At least one surface of the lens is provided with a metal coating; the surface is at least one of the following: the front surface (7) of the lens barrel, the front surface (8) of the retaining ring of the first lens (1), the lens barrel plane (9) that contacts the rear surface of the first lens (1), and the front surface (10) of the retaining ring of the second lens (2).

7. The low-thermal-effect radiation-resistant alarm optical lens according to claim 6, characterized in that: The metal film is a gold film.

8. The low-heat-effect radiation-resistant alarm optical lens according to claim 1, characterized in that: The lens operates in a temperature range of -35℃ to 70℃.

9. The low-thermal-effect radiation-resistant alarm optical lens according to claim 1, characterized in that: The lens is configured to be used in conjunction with a four-quadrant detector. The incident light angle is determined by calculating the differential energy ratio of the four quadrants using the following formula: ((Energy of Region 1 + Energy of Region 2) - (Energy of Region 3 + Energy of Region 4)) / (Energy of Region 1 + Energy of Region 2 + Energy of Region 3 + Energy of Region 4) Among them, regions 1 to 4 are the four quadrants of the image plane of the four-quadrant detector divided according to rectangular coordinates.

10. The low-thermal-effect radiation-resistant alarm optical lens according to claim 1, characterized in that: The inner wall of the lens barrel is provided with matte threads.

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