Optical lens with a wide field of view and wide spectrum for star sensors with a wide operating temperature range

Abstract

This invention discloses a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range, belonging to the field of satellite attitude measurement and navigation. The invention comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth focusing imaging surface arranged coaxially. The optical lens is composed of seven coaxially arranged spherical lenses. Temperature characteristics are matched by selecting four optical glass materials and an aluminum mechanical structure. The optical power of the spherical lens group is allocated to achieve passive, thermal optical configuration. Thermal aberration correction is achieved by matching the glass refractive index, lens power, and expansion coefficient of the lens barrel structure of the seven spherical lenses, enabling near-diffraction-limited imaging performance over a wide operating temperature range. This invention offers advantages such as a large field of view, small size, light weight, wide operating temperature range, low chromatic aberration, and low distortion.

Description

Technical Field

[0001] This invention relates to a large field-of-view, wide-spectrum, lightweight star sensor optical lens with a wide operating temperature range, belonging to the field of satellite attitude measurement and navigation. Background Technology

[0002] Star sensors are key instruments for achieving autonomous attitude measurement and flight control of satellites. They measure the angular distances between stars in the sky by capturing images of star points and match them in real-time with a database of stars at known precise locations. This yields the exterior orientation elements of the spaceborne remote sensing camera, enabling high-precision positioning measurements of satellite attitude and ground-based remote sensing images without control points. The image quality of the stars is a crucial factor affecting the accuracy of angular distance measurements; therefore, the performance of a star sensor largely depends on the performance of its optical system.

[0003] Because starlight has a weak signal, star sensor optical lenses typically have large relative apertures and wide imaging spectral ranges to improve detection sensitivity and star image signal-to-noise ratio. This allows them to capture higher energy star targets, lower the threshold star for star sensor observation, and simultaneously shorten exposure time, reduce star image displacement, and improve the accuracy of barycenter positioning. Star sensor optical lenses with a large field of view can increase the number of matchable stars, thereby improving the accuracy of star image recognition and matching and satellite attitude measurement. However, aberration correction at the edge of the field of view is difficult, and residual coma, astigmatism, field curvature, and distortion are large, resulting in a decrease in the circularity of star spot at the edge of the field of view (appearing elliptical). This not only results in low energy concentration but also affects the subsequent extraction of the barycenter position.

[0004] On the other hand, star sensors operating in orbit are mounted on satellite bulkheads or camera back supports, directly exposing them to the space environment. For sun-synchronous orbit satellites at altitudes of 500km to 650km, the alternating high and low temperature cycles caused by sunlight and shadow occur more than ten times a day, creating an extremely harsh temperature environment. The refractive index of optical glass is highly sensitive to temperature changes and exhibits thermally induced inhomogeneity. Optical elements deform with temperature variations, causing changes in their radius of curvature and thickness. The mechanical structure materials of the lens barrel expand and contract with temperature changes, altering the spacing between optical elements. These temperature-dependent parameter changes severely degrade the imaging quality of the optical system. A heatless design under large temperature differences is required through the rational matching and optimization of the thermal expansion coefficients and refractive index temperature coefficients of optical and mechanical materials. However, the temperature range within which existing star sensor lenses can operate normally generally does not exceed 80 degrees Celsius.

[0005] Therefore, how to provide a star sensor optical lens that can achieve full-field correction of coma, astigmatism, field curvature and distortion while also possessing large relative aperture, large field of view, wide spectral range, large temperature difference operating range and lightweight performance has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The main objective of this invention is to provide a wide-field-of-view, wide-spectrum star sensor optical lens with a broad operating temperature range, capable of acquiring star point images with low aberrations and multiple star samples, thereby improving the matching accuracy of star map recognition and the accuracy of satellite attitude measurement. The star sensor optical lens employs a fully transmissive optical path layout structure, achieving thermal and chromatic aberration correction of the system by allocating and optimizing the optical power of each lens, while also addressing distortion aberration correction at the edge of the field of view. This invention offers advantages such as a large field of view, small size, light weight, wide operating temperature range, low chromatic aberration, and low distortion.

[0007] The objective of this invention is achieved through the following technical solution.

[0008] This invention discloses a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth focusing imaging surface arranged coaxially. The optical lens is composed of seven coaxially arranged spherical lenses. Temperature characteristics are matched by selecting four different optical glass materials and an aluminum mechanical structure. The optical power of the spherical lens group is also allocated to achieve passive, thermal-free optical configuration. Thermal aberration correction is achieved by matching the refractive index of the seven spherical lenses, the optical power of the lenses, and the coefficient of thermal expansion of the lens barrel structure, enabling the optical lens to achieve near-diffraction-limited imaging performance over a wide operating temperature range.

[0009] To ensure the field curvature aberration correction effect of the optical lens, the thickness of the first lens is 8.51mm to 8.55mm, the radius of curvature of the front surface is 47.41mm to 47.51mm, the radius of curvature of the rear surface is -106.44mm to -106.24mm, and the distance from the front surface of the second lens is 1.52mm to 1.56mm. The optical glass designation is N-BAK2. Preferably, the thickness of the first lens is 8.53mm, the radius of curvature of the front surface is 47.46mm, the radius of curvature of the rear surface is -106.34mm, the distance from the front surface of the second lens is 1.54mm, and the optical glass designation is N-BAK2.

[0010] To ensure the field curvature correction effect of the optical lens, the second lens has a thickness of 1.48mm to 1.52mm, a front surface radius of curvature of -42.04mm to -41.96mm, a rear surface radius of curvature of -70.29mm to -70.15mm, and a distance of 8.98mm to 9.02mm from the front surface of the third lens. The optical glass designation is N-SK5. Preferably, the second lens has a thickness of 1.50mm, a front surface radius of curvature of -42.00mm, a rear surface radius of curvature of -70.22mm, and a distance of 9.00mm from the front surface of the third lens. The optical glass designation is N-SK5.

[0011] To ensure effective correction of spherical and coma aberrations in the optical lens, the third lens has a thickness of 7.68mm to 7.72mm, a front surface radius of curvature of 19.12mm to 19.16mm, a rear surface radius of curvature (the system aperture stop) of 47.80mm to 47.90mm, and a distance of 2.78mm to 2.82mm from the front surface of the fourth lens. The optical glass designation is N-SK5. Preferably, the third lens has a thickness of 7.70mm, a front surface radius of curvature of 19.14mm, a rear surface radius of curvature of 47.85mm, and a distance of 2.80mm from the front surface of the fourth lens. The optical glass designation is also N-SK5.

[0012] To ensure effective correction of spherical and coma aberrations in the optical lens, the fourth lens has a thickness of 5.80mm to 5.84mm, a front surface radius of curvature of -127.96mm to -127.70mm, a rear surface radius of curvature of 19.36mm to 19.40mm, and a distance of 2.65mm to 2.69mm from the front surface of the fifth lens. The optical glass designation is SF57. Preferably, the fourth lens has a thickness of 5.82mm, a front surface radius of curvature of -127.83mm, a rear surface radius of curvature of 19.38mm, and a distance of 2.67mm from the front surface of the fifth lens. The optical glass designation is also SF57.

[0013] To ensure the distortion and aberration correction effect of the optical lens, the fifth lens has a thickness of 1.88mm to 1.92mm, a front surface radius of curvature of 283.20mm to 283.24mm, a rear surface radius of curvature of -23.87mm to -23.83mm, and a distance of 0.28mm to 0.32mm from the front surface of the sixth lens. The optical glass designation is N-FK5. Preferably, the fifth lens has a thickness of 1.90mm, a front surface radius of curvature of 283.22mm, a rear surface radius of curvature of -23.85mm, and a distance of 0.30mm from the front surface of the sixth lens. The optical glass designation is N-FK5.

[0014] To ensure the distortion and aberration correction effect of the optical lens, the sixth lens has a thickness of 2.41mm to 2.45mm, a front surface radius of curvature of 25.66mm to 25.72mm, a rear surface radius of curvature of -72.07mm to -72.93mm, and a distance of 0.28mm to 0.32mm from the front surface of the seventh lens. The optical glass designation is N-SK5. Preferably, the sixth lens has a thickness of 2.43mm, a front surface radius of curvature of 25.69mm, a rear surface radius of curvature of -72.00mm, and a distance of 0.30mm from the front surface of the seventh lens. The optical glass designation is also N-SK5.

[0015] To ensure the axial and magnification chromatic aberration correction effects of the optical lens, the seventh lens has a thickness of 8.93mm to 8.97mm, a front surface radius of curvature of 16.53mm to 16.57mm, a rear surface radius of curvature of 11.32mm to 11.34mm, and a distance of 4.98mm to 5.02mm from the front surface of the eighth lens. The optical glass designation is SF57. Preferably, the seventh lens has a thickness of 8.95mm, a front surface radius of curvature of 16.55mm, a rear surface radius of curvature of 11.33mm, and a distance of 5.00mm from the front surface of the eighth lens. The optical glass designation is also SF57.

[0016] The eighth surface is a focusing imaging surface, which can be a visible light detector with a specification of 512×512 and a pixel size of 25μm.

[0017] The present invention discloses an optical lens for a wide-field-of-view, wide-spectrum star sensor with a wide operating temperature range. The operating wavelength is 0.4μm to 0.9μm, the system focal length is 28mm, the relative aperture is 1 / 1.45, the full field of view is 24°, the total system length is 58.5mm, and the total weight of the lens is only 42g. It can observe stars of magnitude 5.5.

[0018] This invention discloses a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range. It exhibits excellent environmental temperature adaptability, maintaining near-diffraction-limited image quality even when operating within a wide temperature range of -100℃ to +100℃. The invented star sensor optical lens offers significant advantages such as a large field of view, wide spectral band, large temperature difference, simple structure, small optical size, and lightweight design.

[0019] The operating method of a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range disclosed in this invention is as follows:

[0020] The wide-field-of-view, wide-spectrum star sensor optical lens, with a wide operating temperature range, detects faint starlight. The incident visible and near-infrared parallel beams of light undergo basic correction for field curvature aberration after passing through the first and second lenses; spherical and coma aberrations are corrected after passing through the third and fourth lenses; distortion aberrations are corrected after passing through the fifth and sixth lenses; and axial and magnification chromatic aberrations are corrected after passing through the seventh lens. In other words, by matching the glass refractive index, lens power, and expansion coefficient of the lens barrel structure of the seven spherical lenses, thermal aberration correction of the optical lens is achieved, enabling it to have near-diffraction-limited imaging performance over a wide operating temperature range.

[0021] Beneficial effects:

[0022] With the widespread application of star sensors in positioning and attitude measurement of satellites, missiles, aircraft, and ships, the requirements for their optical performance are becoming increasingly stringent. The development direction of star sensor optical lenses is to simultaneously meet the requirements of imaging systems such as large field of view, wide spectral band, large temperature difference environment, large relative aperture, and miniaturization, while also satisfying the high-precision star map matching needs of large sky areas and low magnitude thresholds. The present invention provides a large field of view, wide spectrum star sensor optical lens with a wide operating temperature range. The beneficial effects that can be achieved in practical applications of satellite autonomous attitude measurement and flight control are as follows:

[0023] 1. This invention discloses a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range. The star sensor optical lens adopts a fully transmissive optical path layout structure. By allocating and optimizing the optical power of each lens, it achieves thermal aberration and chromatic aberration correction of the system, while also taking into account distortion aberration correction at the edge of the field of view. It has a large star point imaging field of view of 24°. Compared with traditional narrow field-of-view star sensor lenses, the large field of view can increase the number of matching stars, thereby improving the accuracy of star map recognition and matching and satellite attitude measurement. Furthermore, the lens of this invention has excellent residual optical aberration correction capability, so that the imaging performance is close to the diffraction limit throughout the entire field of view.

[0024] 2. The present invention discloses an optical lens for a wide-field-of-view, wide-spectrum star sensor with a wide operating temperature range. It operates in a wide spectral range of 0.4μm to 0.9μm. Compared with traditional star sensor lenses that only operate in the visible light band, the visible light and near-infrared bands it covers can significantly improve the detection sensitivity and signal-to-noise ratio of the star sensor, thereby helping to shorten the exposure time, reduce star image displacement, and improve the accuracy of centroid positioning.

[0025] 3. The present invention discloses a wide field-of-view wide spectrum star sensor optical lens with a wide operating temperature range. It utilizes the optical power distribution between lenses to achieve passive thermal aberration correction. This passive anechoic design makes the system structure simple. Compared with the active anechoic design, it can achieve thermal defocus compensation over a wide temperature range without complex moving parts. Attached Figure Description

[0026] Figure 1 Optical path structure diagram of a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range;

[0027] Figure 2 Dot plot of a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range;

[0028] Figure 3 A graph showing the root mean square radius of the image plane speckle as a function of wavelength for a wide field of view, wide spectrum star sensor optical lens with a wide operating temperature range.

[0029] Figure 4 A graph showing the root mean square radius of the image plane speckle as a function of the field of view for a wide-field, wide-spectrum star sensor optical lens with a wide operating temperature range.

[0030] Figure 5 Modulation transfer function curve of a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range at 20°C.

[0031] Figure 6 A graph showing the energy fraction of the image plane geometry surrounding the circle of a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range as a function of the radius.

[0032] Figure 7 A graph showing the variation of the root mean square radius of the image plane speckle of a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range as a function of the system defocusing amount.

[0033] Figure 8 A graph showing the modulation transfer function of a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range as a function of the system defocusing amount.

[0034] Figure 9 Field curvature aberration curves and distortion aberration curves of a wide field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range;

[0035] Figure 10 A graph showing the relative irradiance of the image plane of a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range as a function of the field of view.

[0036] Figure 11A graph showing the root mean square radius of the image plane speckle as a function of wavelength for a wide field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range at -100℃.

[0037] Figure 12 Modulation transfer function curve of a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range at -100℃.

[0038] Figure 13 A graph showing the root mean square radius of the image plane speckle as a function of wavelength for a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range at 100°C.

[0039] Figure 14 Modulation transfer function curve of a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range at 100℃.

[0040] Among them, 1—first lens, 2—second lens, 3—third lens, 4—fourth lens, 5—fifth lens, 6—sixth lens, 7—seventh lens, and 8—eighth focusing imaging surface. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention 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 illustrative and not intended to limit the invention.

[0042] like Figure 1 As shown, this embodiment discloses an optical lens for a wide-field-of-view, wide-spectrum star sensor with a wide operating temperature range. It includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth focusing imaging surface arranged coaxially. The optical lens is composed of seven coaxially arranged spherical lenses. Temperature characteristics are matched by selecting four optical glass materials and specific mechanical structure materials. Simultaneously, the optical power of the spherical lens group is allocated to achieve passive, thermal optical design and various aberration corrections. The eighth surface is the focusing imaging surface, located at the detector's position.

[0043] The first lens 1 has a thickness of 8.51mm to 8.55mm, a front surface radius of curvature of 47.41mm to 47.51mm, a rear surface radius of curvature of -106.44mm to -106.24mm, and a distance of 1.52mm to 1.56mm from the front surface of the second lens 2. The optical glass designation is N-BAK2. Preferably, the first lens 1 has a thickness of 8.53mm, a front surface radius of curvature of 47.46mm, a rear surface radius of curvature of -106.34mm, and a distance of 1.54mm from the front surface of the second lens 2. The optical glass designation is N-BAK2.

[0044] The second lens 2 has a thickness of 1.48mm to 1.52mm, a front surface radius of curvature of -42.04mm to -41.96mm, a rear surface radius of curvature of -70.29mm to -70.15mm, and a distance of 8.98mm to 9.02mm from the front surface of the third lens 3. The optical glass designation is N-SK5. Preferably, the second lens 2 has a thickness of 1.50mm, a front surface radius of curvature of -42.00mm, a rear surface radius of curvature of -70.22mm, and a distance of 9.00mm from the front surface of the third lens 3. The optical glass designation is N-SK5.

[0045] The third lens 3 has a thickness of 7.68 mm to 7.72 mm, a front surface radius of curvature of 19.12 mm to 19.16 mm, a rear surface (which is the system aperture stop) radius of curvature of 47.80 mm to 47.90 mm, and a distance of 2.78 mm to 2.82 mm from the front surface of the fourth lens 4. The optical glass designation is N-SK5. Preferably, the third lens 3 has a thickness of 7.70 mm, a front surface radius of curvature of 19.14 mm, a rear surface radius of curvature of 47.85 mm, and a distance of 2.80 mm from the front surface of the fourth lens 4. The optical glass designation is N-SK5.

[0046] The fourth lens 4 has a thickness of 5.80mm to 5.84mm, a front surface radius of curvature of -127.96mm to -127.70mm, a rear surface radius of curvature of 19.36mm to 19.40mm, and a distance of 2.65mm to 2.69mm from the front surface of the fifth lens 5. The optical glass designation is SF57. Preferably, the fourth lens 4 has a thickness of 5.82mm, a front surface radius of curvature of -127.83mm, a rear surface radius of curvature of 19.38mm, and a distance of 2.67mm from the front surface of the fifth lens 5. The optical glass designation is SF57.

[0047] The fifth lens 5 has a thickness of 1.88mm to 1.92mm, a front surface radius of curvature of 283.20mm to 283.24mm, a rear surface radius of curvature of -23.87mm to -23.83mm, and a distance of 0.28mm to 0.32mm from the front surface of the sixth lens 6. The optical glass designation is N-FK5. Preferably, the fifth lens 5 has a thickness of 1.90mm, a front surface radius of curvature of 283.22mm, a rear surface radius of curvature of -23.85mm, and a distance of 0.30mm from the front surface of the sixth lens 6. The optical glass designation is N-FK5.

[0048] The sixth lens 6 has a thickness of 2.41mm to 2.45mm, a front surface radius of curvature of 25.66mm to 25.72mm, a rear surface radius of curvature of -72.07mm to -72.93mm, and a distance of 0.28mm to 0.32mm from the front surface of the seventh lens 7. The optical glass designation is N-SK5. Preferably, the sixth lens 6 has a thickness of 2.43mm, a front surface radius of curvature of 25.69mm, a rear surface radius of curvature of -72.00mm, and a distance of 0.30mm from the front surface of the seventh lens 7. The optical glass designation is N-SK5.

[0049] The seventh lens 7 has a thickness of 8.93mm to 8.97mm, a front surface radius of curvature of 16.53mm to 16.57mm, a rear surface radius of curvature of 11.32mm to 11.34mm, and a distance of 4.98mm to 5.02mm from the front surface of the eighth lens 8. The optical glass designation is SF57. Preferably, the seventh lens 7 has a thickness of 8.95mm, a front surface radius of curvature of 16.55mm, a rear surface radius of curvature of 11.33mm, and a distance of 5.00mm from the front surface of the eighth lens 8. The optical glass designation is SF57.

[0050] The eighth surface is the focusing imaging surface 8, which can be a visible light detector with a size of 512×512 and a pixel size of 25μm.

[0051] The optical lens of the wide-field-of-view, wide-spectrum star sensor of this invention has a wide operating temperature range of 0.4μm to 0.9μm, a system focal length of 28mm, a relative aperture of 1 / 1.45, a full field of view of 24°, a total system length of 58.5mm, a total lens weight of only 42g, can observe stars of magnitude 5.5, has a detector size of 512×512, and a pixel size of 25μm.

[0052] Furthermore, within the entire field of view, the wide-field-of-view, wide-spectrum star sensor optical lens of this embodiment of the invention, with a wide operating temperature range, exhibits a modulation transfer function greater than 0.6 at the Nyquist frequency of 20 lp / mm, a maximum root-mean-square radius of 10.916 μm for the largest speckle, and a geometrically enclosing circle energy ratio better than 80% within a 25 μm pixel size. The image plane illumination of 0.934 at the edge field of view indicates uniform image plane imaging, with a maximum relative distortion of less than 0.44%. Within a wide temperature range of -100℃ to +100℃, the system's modulation transfer function at 20 lp / mm is greater than 0.55, and the imaging quality is close to the diffraction limit.

[0053] The operating method of a wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range disclosed in this embodiment is as follows:

[0054] A wide-field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range detects faint starlight. The incident visible and near-infrared parallel beams of light pass through the first lens 1 and the second lens 2 to achieve basic correction of field curvature aberration; after passing through the third lens 3 and the fourth lens 4, spherical aberration and coma aberration are corrected; after passing through the fifth lens 5 and the sixth lens 6, distortion aberration is corrected; and after passing through the seventh lens 7, axial and magnification chromatic aberration are corrected. That is, by matching the glass refractive index, lens power, and expansion coefficient of the lens barrel structure of the seven spherical lenses 7, thermal aberration correction of the optical lens is achieved. Imaging is performed on the eighth focusing imaging plane 8, giving it near-diffraction-limited imaging performance over a wide operating temperature range.

[0055] Figure 2 This is a dot plot of the optical lens of the large field-of-view, wide-spectrum star sensor with a wide operating temperature range according to an embodiment of the present invention. Figure 3 This is a graph showing the root-mean-square radius of the image plane dispersion spot as a function of wavelength for an optical lens with a wide field of view and wide spectrum, which has a wide operating temperature range, according to an embodiment of the present invention. Figure 4 This is a graph showing the root-mean-square radius of the image plane dispersion spot as a function of the field of view for a wide-field, wide-spectrum star sensor optical lens with a wide operating temperature range according to an embodiment of the present invention. Figure 5 This is a modulation transfer function curve of the large field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range according to an embodiment of the present invention at 20°C. Figure 6 This is a graph showing the energy percentage of the image plane geometrically enclosed circle as a function of the radius of the optical lens of a wide-field-of-view, wide-spectrum star sensor with a wide operating temperature range, according to an embodiment of the present invention. Figures 2-6 The curves all indicate that the imaging quality of the large field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range in the embodiments of the present invention is close to the diffraction limit.

[0056] Figure 7This is a graph showing the variation of the root-mean-square radius of the image plane dispersion spot of the optical lens with a wide field of view and wide spectrum, which has a wide operating temperature range, as a function of the system defocusing amount, according to an embodiment of the present invention. Figure 8 This is a graph showing the modulation transfer function of the optical lens of a large field-of-view, wide-spectrum star sensor with a wide operating temperature range as a function of the system defocusing amount, according to an embodiment of the present invention. Figure 9 The field curvature aberration curve and distortion aberration curve of the optical lens of the large field of view wide spectrum star sensor with a wide operating temperature range are shown in the embodiments of the present invention.

[0057] Figure 10 This is a graph showing the relative irradiance of the image plane of the optical lens of a wide-field-of-view, wide-spectrum star sensor with a wide operating temperature range as a function of the field of view, according to an embodiment of the present invention. Figures 7-10 The curves all show that the field curvature, distortion, defocus and other aberrations of the large field of view wide spectrum star sensor optical lens with a wide temperature operating range in the embodiments of the present invention are well corrected, and the aberration correction capability of the optical lens is excellent.

[0058] Figure 11 This is a graph showing the root-mean-square radius of the image plane dispersion spot as a function of wavelength in an optical lens with a wide field of view and wide spectrum, which has a wide operating temperature range, in an environment of -100℃, according to an embodiment of the present invention. Figure 12 This is a modulation transfer function curve of the large field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range according to an embodiment of the present invention, at an environment of -100℃. Figure 13 This is a graph showing the root-mean-square radius of the image plane dispersion spot as a function of wavelength for an optical lens with a wide field of view and wide spectrum, which has a wide operating temperature range, in an environment of 100°C, according to an embodiment of the present invention. Figure 14 This is a modulation transfer function curve of the large field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range in an environment of 100°C, according to an embodiment of the present invention. Figures 11-14 The curves all show that the modulation transfer function of the wide field-of-view, wide-spectrum star sensor optical lens with a wide operating temperature range in the embodiments of the present invention is close to the diffraction limit at temperatures ranging from -100℃ to 100℃, and the imaging quality is good.

[0059] In summary, the large field-of-view, wide-spectrum star sensor optical lens of this invention, with a wide operating temperature range, employs a coaxially arranged seven-element spherical lens assembly structure, resulting in a system with extremely small optical volume and weight. By rationally combining optical and structural materials and appropriately distributing the optical power of the lens group, the impact of temperature variations on the optical system's performance is reduced. The system exhibits good imaging quality over a wide temperature range and excellent environmental adaptability. This invention can be applied to positioning and attitude determination on platforms such as satellites, missiles, aircraft, and ships.

[0060] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An optical lens for a wide-field-of-view, wide-spectrum star sensor with a wide operating temperature range, characterized in that: It includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth focusing imaging surface arranged coaxially. The optical lens is composed of seven coaxially arranged spherical lenses. The temperature characteristics are matched by selecting four optical glass materials and an aluminum mechanical structure. At the same time, the optical power of the spherical lens group is allocated to achieve passive and thermal optical arrangement. By matching the glass refractive index, lens power, and expansion coefficient of the lens barrel structure of the seven spherical lenses, thermal aberration correction of the optical lens is achieved, so that it has near-diffraction-limited imaging performance over a wide operating temperature range. The first lens has a thickness of 8.51mm to 8.55mm, a front surface curvature radius of 47.41mm to 47.51mm, a rear surface curvature radius of -106.44mm to -106.24mm, and a distance of 1.52mm to 1.56mm from the front surface of the second lens. The optical glass designation is N-BAK2. The second lens has a thickness of 1.48mm to 1.52mm, a front surface curvature radius of -42.04mm to -41.96mm, a rear surface curvature radius of -70.29mm to -70.15mm, and a distance of 8.98mm to 9.02mm from the front surface of the third lens. The optical glass designation is N-SK5. The third lens has a thickness of 7.68mm to 7.72mm, a front surface curvature radius of 19.12mm to 19.16mm, a rear surface curvature radius of 47.80mm to 47.90mm, and a distance of 2.78mm to 2.82mm from the front surface of the fourth lens. The optical glass designation is N-SK5. The fourth lens has a thickness of 5.80mm to 5.84mm, a front surface curvature radius of -127.96mm to -127.70mm, a rear surface curvature radius of 19.36mm to 19.40mm, and a distance of 2.65mm to 2.69mm from the front surface of the fifth lens. The optical glass designation is SF57. The fifth lens has a thickness of 1.88mm to 1.92mm, a front surface radius of curvature of 283.20mm to 283.24mm, a rear surface radius of curvature of -23.87mm to -23.83mm, and a distance of 0.28mm to 0.32mm from the front surface of the sixth lens. The optical glass designation is N-FK5. The sixth lens has a thickness of 2.41mm to 2.45mm, a front surface curvature radius of 25.66mm to 25.72mm, a rear surface curvature radius of -72.07mm to -72.93mm, and a distance of 0.28mm to 0.32mm from the front surface of the seventh lens. The optical glass designation is N-SK5. The seventh lens has a thickness of 8.93mm to 8.97mm, a front surface curvature radius of 16.53mm to 16.57mm, a rear surface curvature radius of 11.32mm to 11.34mm, and a distance of 4.98mm to 5.02mm from the front surface of the eighth lens. The optical glass designation is SF57.

2. The optical lens for a wide-field-of-view, wide-spectrum star sensor with a wide operating temperature range as described in claim 1, characterized in that: The first lens has a thickness of 8.53 mm, a front surface curvature radius of 47.46 mm, a rear surface curvature radius of -106.34 mm, and a distance of 1.54 mm from the front surface of the second lens. The optical glass designation is N-BAK2. The second lens is 1.50mm thick, with a front surface radius of curvature of -42.00mm and a rear surface radius of curvature of -70.22mm. It is 9.00mm away from the front surface of the third lens, and its optical glass designation is N-SK5. The third lens has a thickness of 7.70 mm, a front surface curvature radius of 19.14 mm, a rear surface curvature radius of 47.85 mm, and a distance of 2.80 mm from the front surface of the fourth lens. The optical glass designation is N-SK5. The fourth lens has a thickness of 5.82 mm, a front surface curvature radius of -127.83 mm, a rear surface curvature radius of 19.38 mm, and a distance of 2.67 mm from the front surface of the fifth lens. Its optical glass designation is SF57. The fifth lens has a thickness of 1.90 mm, a front surface radius of curvature of 283.22 mm, a rear surface radius of curvature of -23.85 mm, and is 0.30 mm away from the front surface of the sixth lens. Its optical glass designation is N-FK5. The sixth lens has a thickness of 2.43 mm, a front surface radius of curvature of 25.69 mm, a rear surface radius of curvature of -72.00 mm, and is 0.30 mm away from the front surface of the seventh lens. Its optical glass designation is N-SK5. The seventh lens has a thickness of 8.95 mm, a front surface curvature radius of 16.55 mm, a rear surface curvature radius of 11.33 mm, and a distance of 5.00 mm from the front surface of the eighth lens. Its optical glass designation is SF57. The eighth surface is the focusing imaging surface, which uses a visible light detector with a specification of 512×512 and a pixel size of 25μm.

3. The optical lens for a large field-of-view, wide-spectrum star sensor with a wide operating temperature range as described in any one of claims 1 to 2, characterized in that: When detecting faint starlight, the incident visible and near-infrared parallel beams of light pass through the first and second lenses to achieve basic correction of field curvature aberration; after passing through the third and fourth lenses, spherical aberration and coma aberration are corrected; after passing through the fifth and sixth lenses, distortion aberration is corrected; and after passing through the seventh lens, axial and magnification chromatic aberration are corrected. That is, by matching the glass refractive index, lens power, and expansion coefficient of the lens barrel structure of the seven spherical lenses, thermal aberration correction of the optical lens is achieved, enabling it to have near-diffraction-limited imaging performance over a wide operating temperature range.

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