An ultra-compact, wide-field-of-view, pyro-spectrum, athermalized conical lens optical structure

Abstract

This invention belongs to the field of optical lens imaging technology and discloses an ultra-compact, wide-field-of-view, pyrotechnic, athermalized conical lens optical structure, composed of nine spherical lenses and one piece of quartz protective glass. The invention features a compact structure with a system length of only 46mm. All lenses have a thickness-to-diameter ratio greater than 0.12, providing resistance to high overload. The first surface curvature radius R1 is 25mm, and the conical shape of the system facilitates overall integration and reduces air resistance during flight. Despite the relatively small length constraint, a 50° wide field of view is achieved, with a telecentric image side and a maximum field-of-view CRA angle of less than 5°, making it suitable for detectors of 1 inch or smaller. It boasts a wide spectral range of 450~850nm and excellent high and low temperature adaptability (-45℃~+65℃). Distortion is low, less than 2% at the maximum field of view, and at 145Lp / mm, the 0.7 field-of-view MTF is greater than 0.35, demonstrating good imaging quality.

Description

Technical Field

[0001] This invention belongs to the field of optical lens imaging technology, and particularly relates to an ultra-compact, wide-field-of-view, wide-spectrum, thermal-free conical lens optical structure. Background Technology

[0002] Currently, various cameras are required in some aircraft for observing the ground and external environment. Due to the numerous internal components of aircraft, the space allocated for lenses is extremely limited, and there are specific requirements for the lens's dimensions to ensure integration into the aircraft system structure. Aircraft travel at high speeds, experiencing high G-forces, sometimes exceeding 1000G. Under these conditions, lenses are easily damaged and lose their imaging function, necessitating optical and mechanical structural designs resistant to high G-forces. Furthermore, during flight, aircraft operate in environments with extreme temperature variations and day-night cycles, and near the ground, they encounter dusty environments. Therefore, there is an urgent need for lenses suitable for these complex and variable environments, ensuring clear and stable imaging.

[0003] In summary, there are many limitations in various aspects. For example: 1) Compact size, with an overall length not exceeding 46mm; 2) The radius of curvature of the first lens surface is limited to 25mm, and the lens shape is conical; 3) Wide spectrum: 450-850nm, for day and night use; 4) Large field of view: 50°; 5) Telecentric image side, with a maximum field of view CRA angle of less than 5°, so there is less concern about image plane defocusing under vibration; 6) Spherical surface: all lenses are spherical glass; 7) High overload: ≥1000G; 8) No pyrolysis: -45~+65℃. Under these conditions, extremely strict requirements are placed on the optical and mechanical structure design of the lens, the selection of lens materials, thickness, optical power design, lens processing precision, and assembly process. The thickness-to-diameter ratio of the lens needs to be comprehensively considered to prevent lens breakage under high overload conditions. The first surface of the first lens needs to be coated with a special protective film to give the lens dustproof, waterproof, and mildew-proof functions.

[0004] Currently, there are many wide-field, athermal visible light (450~650nm) lenses on the market, but there is no conical lens that can simultaneously meet the above requirements of ultra-compactness, wide field of view, wide spectrum, athermalization, global plane, and resistance to high overload. This invention provides a lens optical structure that can meet the above-mentioned many limitations and complex application environments, filling a market gap.

[0005] Based on the above analysis, the existing technology has the following problems and defects: There are many wide field-of-view, non-thermal visible light (450~650nm) lenses on the market, but there is no conical lens that can simultaneously meet the above requirements of ultra-compactness, wide field of view, wide spectrum, non-thermalization, global surface, and resistance to high overload.

[0006] The difficulty in solving the above problems and defects lies in the numerous constraints and complex application environment.

[0007] The significance of solving the above problems and defects is that it provides a lens optical structure that meets the above-mentioned many constraints and complex application environments, filling a market gap. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides an ultra-compact, wide-field-of-view, wide-spectrum, thermal-free conical lens optical structure. The lens of this invention provides clear and stable imaging, a large field of view, a wide spectral range suitable for day and night use, resistance to high overload and adaptability to high and low temperatures, and is dustproof, waterproof, and mildew-proof, meeting the specific application requirements of this field.

[0009] The present invention is implemented as follows: an ultra-compact wide field of view, wide spectrum, athermalized conical lens optical structure, wherein the ultra-compact wide field of view, wide spectrum, athermalized conical lens optical structure is provided with: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a protective glass, and an image plane;

[0010] The first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens, protective glass and image plane are arranged coaxially in sequence, and the optical powers of the lenses are negative, positive, positive, positive, positive, negative, positive, negative and positive, respectively.

[0011] Furthermore, the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, and ninth lens are all spherical mirrors;

[0012] The thickness-to-diameter ratio of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, and ninth lens is greater than or equal to 0.12;

[0013] The overall length of the ultra-compact, wide-field-of-view, pyromagnetic, conical lens optical structure is 46mm, and the radius of curvature R1 of the first surface of the first lens is fixed at 25mm. The overall shape of the lens is conical.

[0014] Furthermore, the first lens and the second lens form a cemented doublet, and the fifth lens, the sixth lens and the seventh lens form a cemented triplet.

[0015] Furthermore, the first lens is a negative lens with a convex-concave structure, an absolute optical power of 0.04-0.05, a light-transmitting aperture of 12mm-14mm, a thickness of 1mm-2mm, R1 of 25mm, and R2 of 7mm-9mm.

[0016] Furthermore, the second lens is a positive lens with a meniscus structure, an absolute optical power of 0.03-0.04, a light-transmitting aperture of 10mm-12mm, a thickness of 2mm-3mm, R1 of 7mm-9mm, and R2 of 8mm-10mm.

[0017] Furthermore, the third lens is a positive lens with a meniscus structure, an absolute optical power of 0.004-0.006, a light-transmitting aperture of 8mm-10mm, a thickness of 2mm-4mm, R1 of 12mm-14mm, and R2 of 12mm-14mm.

[0018] Furthermore, the fourth lens is a positive lens with a plano-convex structure, an absolute optical power of 0.07-0.09, a light-transmitting aperture of 5mm-7mm, a thickness of 2mm-4mm, R1 of 9mm-11mm, and R2 of 88mm-90mm; the fifth lens is a positive lens with a convex-concave structure, an absolute optical power of 0.08-0.1, a light-transmitting aperture of 6mm-8mm, a thickness of 2mm-4mm, R1 of 25mm-27mm, and R2 of 5mm-7mm.

[0019] Furthermore, the sixth lens is a negative lens with a biconcave structure, an absolute optical power of 0.2-0.3, a light-transmitting aperture of 7mm-10mm, a thickness of 1mm-3mm, R1 of 5mm-7mm, and R2 of 5mm-7mm.

[0020] The seventh lens is a positive lens with a biconvex structure. Its absolute optical power is 0.1-0.2, its aperture is 9mm-11mm, its thickness is 5mm-7mm, its R1 is 5mm-7mm, and its R2 is 15mm-17mm.

[0021] Furthermore, the eighth lens is a negative lens with a meniscus structure, an absolute optical power of 0.03-0.04, a light-transmitting aperture of 10mm-15mm, a thickness of 4mm-6mm, R1 of 5mm-7mm, and R2 of 9mm-11mm;

[0022] The ninth lens is a positive lens with a biconvex structure, an absolute optical power of 0.04-0.05, an aperture of 18mm-20mm, a thickness of 5mm-7mm, R1 of 35mm-39mm, and R2 of 49mm-53mm.

[0023] Furthermore, the protective glass is made of fused silica, with a light-transmitting aperture of 23mm and a thickness of 2mm-3mm. The first surface of the first lens is coated with a three-proof film.

[0024] Combining all the above technical solutions, the advantages and positive effects of this invention are as follows:

[0025] The present invention has a compact structure with an overall system length of only 46mm. The radius of curvature R1 of the first surface of the first lens is fixed at 25mm. The overall shape of the lens is conical, and the smooth aerodynamic shape helps to integrate the overall system and reduce the air resistance of the aircraft during flight.

[0026] The present invention has a large field of view. Under the constraint of a small length dimension (TOTR=46mm), a large field of view (50° full field of view) is achieved, which can be adapted to detectors of 1 inch and below; and the distortion is small, less than 2% across the entire field of view, resulting in good imaging quality.

[0027] The present invention has a wide spectral range, from 450nm to 850nm, which can acquire more color information, and the image quality is closer to the object itself. It can also receive near-infrared light when there is no visible light illumination at night, making it more adaptable to various environments. It can be adapted to black and white or color detectors.

[0028] This invention features an optical structure design resistant to high overload (≥1000G), with all lenses having a thickness-to-diameter ratio greater than or equal to 0.12; the structure of the optical system, the material, thickness, and optical power of the lenses are rationally selected, enabling clear and stable imaging.

[0029] This invention can adapt to a wide temperature range (-45~+65℃), within which it can produce clear and stable images without the need for refocusing, resulting in high reliability.

[0030] The lenses of this invention have spherical surfaces, and the processing, assembly, and testing technologies are mature and the cost is low.

[0031] The present invention has an F# of 4, uniform relative illumination, no vignetting, and relative illumination ≥80%; the principal ray incident angle CRA at the maximum field of view on the image plane is controlled within 5°, the image side is telecentric, and the image plane defocusing under conditions such as vibration prevents imaging blurring caused by the image plane defocusing, and the system has higher reliability.

[0032] The present invention has a large back focal length BFL (distance from the center of the rear surface of the ninth lens to the image plane), BFL=7.58mm, which facilitates adjustment. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the optical structure of the ultra-compact, wide-field-of-view, wide-spectrum, athermalized conical lens provided in an embodiment of the present invention;

[0034] In the diagram: 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Eighth lens; 9. Ninth lens; 10. Protective glass; 11. Image plane.

[0035] Figure 2This is a distortion image provided in an embodiment of the present invention.

[0036] Figure 3 This is a schematic diagram of the imaging quality under conditions of -45~+65℃ provided in the embodiments of the present invention.

[0037] Figures: Figure (a) shows the dispersion spot radius and MTF curve at 25℃; Figure (b) shows the dispersion spot radius and MTF curve at 65℃; Figure (c) shows the dispersion spot radius and MTF curve at -45℃.

[0038] Figure 4 This is a schematic diagram of the relative illumination curve provided in an embodiment of the present invention.

[0039] Figure 5 This is a schematic diagram of the principal ray incident angle (CRA) provided in an embodiment of the present invention.

[0040] Figure 6 This is a dot diagram of the optical system provided in an embodiment of the present invention.

[0041] Figure 7 This is an optical modulation transfer function (MTF) curve provided in an embodiment of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] To address the problems existing in the prior art, the present invention provides an ultra-compact, wide-field-of-view, wide-spectrum, thermal-free conical lens optical structure. The present invention will be described in detail below with reference to the accompanying drawings.

[0044] The ultra-compact, wide-field-of-view, wide-spectrum, thermochromic conical lens optical structure provided by this invention can also be implemented using other steps by those skilled in the art. Figure 1 The ultra-compact, wide-field-of-view, wide-spectrum, athermalized conical lens optical structure provided by this invention is merely one specific embodiment.

[0045] like Figure 1As shown, the ultra-compact, wide-field-of-view, pyrotechnic conical lens optical structure provided in this embodiment of the invention includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, a ninth lens 9, a protective glass 10, and an image plane 11. The first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the eighth lens 8, the ninth lens 9, the protective glass 10, and the image plane 11 are arranged coaxially in sequence, and the optical powers of the lenses are negative, positive, positive, positive, positive, positive, negative, positive, negative, and positive, respectively. Among them, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the eighth lens 8, and the ninth lens 9 are all spherical mirrors. The first lens 1 and the second lens 2 form a cemented doublet lens, and the fifth lens 5, the sixth lens 6 and the seventh lens 7 form a cemented triplet lens; the thickness-to-diameter ratio of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the eighth lens 8 and the ninth lens 9 is greater than or equal to 0.12.

[0046] The first lens 1 is a negative lens with a convex-concave structure, an absolute optical power of 0.04-0.05, an aperture of 12mm-14mm, a thickness of 1mm-2mm, R1 of 25mm, and R2 of 7mm-9mm; the second lens 2 is a positive lens with a meniscus structure, an absolute optical power of 0.03-0.04, an aperture of 10mm-12mm, a thickness of 2mm-3mm, R1 of 7mm-9mm, and R2 of 8mm-10mm; the third lens 3 is a positive lens with a meniscus structure, an absolute optical power of 0.004-0.006, an aperture of 8mm-10mm, a thickness of 2mm-4mm, R1 of 12mm-14mm, and R2 of 12mm-14mm. The fourth lens (4) is a positive lens with a plano-convex structure, an absolute optical power of 0.07-0.09, an aperture of 5mm-7mm, a thickness of 2mm-4mm, R1 of 9mm-11mm, and R2 of 88mm-90mm. The fifth lens (5) is also a positive lens with a convex-concave structure, an absolute optical power of 0.08-0.1, an aperture of 6mm-8mm, a thickness of 2mm-4mm, R1 of 25mm-27mm, and R2 of 5mm-7mm. The sixth lens (6) is a negative lens with a biconcave structure, an absolute optical power of 0.2-0.3, an aperture of 7mm-10mm, a thickness of 1mm-3mm, R1 of 5mm-7mm, and R2 of 5mm. -7mm; the seventh lens 7 is a positive lens with a biconvex structure, an absolute optical power of 0.1-0.2, a light-transmitting aperture of 9mm-11mm, a thickness of 5mm-7mm, R1 of 5mm-7mm, and R2 of 15mm-17mm; the eighth lens 8 is a negative lens with a meniscus structure, an absolute optical power of 0.03-0.04, a light-transmitting aperture of 10mm-15mm, a thickness of 4mm-6mm, R1 of 5mm-7mm, and R2 of 9mm-11mm; the ninth lens 9 is a positive lens with a biconvex structure, an absolute optical power of 0.04-0.05, a light-transmitting aperture of 18mm-20mm, a thickness of 5mm-7mm, R1 of 35mm-39mm, and R2 of 49mm-53mm; the protective glass 10 is made of fused silica, with a light-transmitting aperture of 23mm and a thickness of 2mm-3mm.

[0047] The technical solution of the present invention will be further described below with reference to simulation experiments.

[0048] The invention has a compact structure with an overall system length of only 46mm. The first surface of the lens has a fixed curvature radius of 25mm, and the overall shape is conical. The smooth aerodynamic shape helps with overall integration and reduces air resistance during flight.

[0049] This invention features a large field of view. Within a relatively small system length (TOTR=46mm), it achieves a large field of view (50° across the entire field of view), making it compatible with detectors 1 inch and smaller; and it exhibits low distortion, with distortion less than 2% across the entire field of view (e.g., ...). Figure 2 As shown in the figure, it has good imaging quality.

[0050] The present invention has a wide spectral range, from 450nm to 850nm, which can acquire more color information, and the image quality is closer to the object itself. It can also receive near-infrared light when there is no visible light illumination at night, making it more adaptable to various environments. It can be adapted to black and white or color detectors.

[0051] This invention features a structural design resistant to high overload (≥1000G), with all lenses having a thickness-to-diameter ratio greater than or equal to 0.12; the optical system's structure, lens materials, thickness, and optical power are rationally selected, enabling clear and stable imaging.

[0052] This invention can adapt to a wide temperature range (-45~+65℃), within which it can produce clear and stable images without the need for refocusing, and has high reliability (e.g., Figure 3 The diagram shows the RMS and MTF curves of the speckle radius at different temperatures.

[0053] The lenses of this invention have spherical surfaces, and the processing, assembly, and testing technologies are mature and the cost is low.

[0054] The F# of this invention is 4, and the relative illumination is uniform (e.g. Figure 4 As shown), there is no vignetting, and the relative illumination is ≥80%; the principal ray incident angle (CRA) at the maximum field of view on the image plane is controlled within 5° (as shown). Figure 5 As shown in the figure, the image plane is telecentric, which prevents image blurring caused by image plane defocusing under conditions such as vibration, and the system has higher reliability.

[0055] The present invention has a large back focal length BFL (distance from the center of the back surface of the ninth lens to the image plane), BFL=7.58mm, which facilitates focusing and adjustment.

[0056] like Figure 6 As shown in the dot plot of the optical system provided by the present invention, the RMS of the blur spot radius across the entire field of view is close to that of the Airy disk, resulting in high imaging quality.

[0057] like Figure 7 As shown, the optical modulation transfer function (MTF) curve provided by the present invention has a high imaging quality at 145 Lp / mm, with a field of view of 0.7 and an MTF ≥ 0.35.

[0058] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0059] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An ultra-compact, wide-field-of-view, broadband, athermalized conical lens optical structure, characterized in that, The ultra-compact, large field-of-view, wide-spectrum, athermalized conical lens optical structure includes: First lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens, protective glass and image plane; The first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens, protective glass and image plane are arranged coaxially in sequence, and the optical powers of the lenses are negative, positive, positive, positive, positive, negative, positive, negative and positive, respectively. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are all spherical mirrors; The thickness-to-diameter ratio of the first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth lenses is greater than or equal to 0.

12. The overall length of the ultra-compact, wide-field-of-view, wide-spectrum, athermalized conical lens optical structure is 46mm, and the radius of curvature R1 of the first surface of the first lens is fixed at 25mm. The overall shape of the lens is conical. Within a system length limit of 46mm TOTR, a large field of view (50°) is achieved, compatible with detectors up to 1 inch in size; distortion is less than 2% across the entire field of view. With a spectral range of 450nm~850nm, it can acquire more color information, and the image quality is closer to the object itself. It can also receive near-infrared light when there is no visible light illumination at night, and is compatible with black and white or color detectors.

2. The ultra-compact, wide-field-of-view, wide-spectrum, thermally insulated conical lens optical structure as described in claim 1, characterized in that, The first and second lenses form a cemented doublet, and the fifth, sixth and seventh lenses form a cemented triplet.

3. The ultra-compact, wide-field-of-view, wide-spectrum, thermally insulated conical lens optical structure as described in claim 1, characterized in that, The first lens is a negative lens with a convex-concave structure, an absolute optical power of 0.04-0.05, a light-transmitting aperture of 12mm-14mm, a thickness of 1mm-2mm, R1 of 25mm, and R2 of 7mm-9mm.

4. The ultra-compact, wide-field-of-view, wide-spectrum, thermally insulated conical lens optical structure as described in claim 1, characterized in that, The second lens is a positive lens with a meniscus structure, an absolute optical power of 0.03-0.04, a light-transmitting aperture of 10mm-12mm, a thickness of 2mm-3mm, R1 of 7mm-9mm, and R2 of 8mm-10mm.

5. The ultra-compact, large field-of-view, wide-spectrum, thermally unaffected conical lens optical structure as described in claim 1, characterized in that... The third lens is a positive lens with a meniscus structure, an absolute optical power of 0.004-0.006, a light-transmitting aperture of 8mm-10mm, a thickness of 2mm-4mm, R1 of 12mm-14mm, and R2 of 12mm-14mm.

6. The ultra-compact, large field-of-view, wide-spectrum, thermally insulated conical lens optical structure as described in claim 1, characterized in that, The fourth lens is a positive lens with a plano-convex structure, an absolute optical power of 0.07-0.09, a light-transmitting aperture of 5mm-7mm, a thickness of 2mm-4mm, an R1 of 9mm-11mm, and an R2 of 88mm-90mm; the fifth lens is a positive lens with a convex-concave structure, an absolute optical power of 0.08-0.1, a light-transmitting aperture of 6mm-8mm, a thickness of 2mm-4mm, an R1 of 25mm-27mm, and an R2 of 5mm-7mm.

7. The ultra-compact, large field-of-view, wide-spectrum, thermally insulated conical lens optical structure as described in claim 1, characterized in that, The sixth lens is a negative lens with a biconcave structure, an absolute optical power of 0.2-0.3, a light-transmitting aperture of 7mm-10mm, a thickness of 1mm-3mm, R1 of 5mm-7mm, and R2 of 5mm-7mm. The seventh lens is a positive lens with a biconvex structure. Its absolute optical power is 0.1-0.2, its aperture is 9mm-11mm, its thickness is 5mm-7mm, its R1 is 5mm-7mm, and its R2 is 15mm-17mm.

8. The ultra-compact, wide-field-of-view, wide-spectrum, thermally insulated conical lens optical structure as described in claim 1, characterized in that, The eighth lens is a negative lens with a meniscus structure, an absolute optical power of 0.03-0.04, a light-transmitting aperture of 10mm-15mm, a thickness of 4mm-6mm, R1 of 5mm-7mm, and R2 of 9mm-11mm. The ninth lens is a positive lens with a biconvex structure, an absolute optical power of 0.04-0.05, an aperture of 18mm-20mm, a thickness of 5mm-7mm, R1 of 35mm-39mm, and R2 of 49mm-53mm.

9. The ultra-compact, large field-of-view, wide-spectrum, thermally insulated conical lens optical structure as described in claim 1, characterized in that, The protective glass is made of fused silica with a light-transmitting aperture of 23mm and a thickness of 2mm-3mm; the first surface of the first lens is coated with a three-proof film.

Images