A high dynamic range star sensor optical lens

Abstract

This invention discloses a large dynamic range star sensor optical lens, comprising: a front lens group, an aperture stop, a rear lens group, and an image plane arranged sequentially from the object side to the image side; the front lens group collects light, corrects aberrations, and forms an intermediate image; the aperture stop controls the light throughput by adjusting its relative aperture; the rear lens group magnifies the intermediate image, corrects aberrations, and forms a final image; the image plane performs optical imaging on the final image; wherein, the front lens group includes: a first positive meniscus lens and a first biconvex lens arranged sequentially from the object side to the image side; the rear lens group includes: a first biconcave lens, a second biconvex lens, a second positive meniscus lens, a first negative meniscus lens, a second biconcave lens, and a first filter arranged sequentially from the object side to the image side. The optical lens provided by this invention has the characteristics of circular spot, large relative aperture, low chromatic aberration, low distortion, high resolution, and small spot morphology and energy deviation after defocusing in various fields of view.

Description

Technical Field

[0001] This invention relates to the field of imaging lens technology, and in particular to a large dynamic range star sensor optical lens. Background Technology

[0002] Star sensors are low-light photoelectric sensors that observe starlight. Due to their high precision and reliability, they are widely used in space missions. However, due to limitations in hardware systems and software algorithms, the dynamic performance of domestically developed star sensors is not high, and they are typically only used during the stable flight phase of the spacecraft.

[0003] With the rapid development of my country's aerospace technology, high-dynamic-range carriers such as agile satellites and long-range weapons are placing higher technical demands on the dynamic performance of star sensors. However, existing star sensor optical lenses cannot simultaneously meet the requirements of high imaging resolution, low image distortion, good image plane blur pattern, and high-precision star point extraction under a large dynamic range. Therefore, designing a high-dynamic-range star sensor optical lens is of great significance to the development of star sensors. Summary of the Invention

[0004] The purpose of this invention is to provide a large dynamic range star sensor optical lens, which aims to solve the problem that existing star sensor optical lenses cannot simultaneously meet the requirements of high imaging resolution, low image distortion, good image plane blur pattern, and high-precision star point extraction under a large dynamic range.

[0005] To achieve the above objectives, the present invention provides a large dynamic range star sensor optical lens, comprising: a front lens group, an aperture stop, a rear lens group, and an image plane arranged sequentially from the object side to the image side; the front lens group collects light, corrects aberrations, and forms an intermediate image; the aperture stop controls the light flux by adjusting its relative aperture; the rear lens group magnifies the intermediate image, corrects aberrations, and forms a final image; the image plane performs optical imaging on the final image;

[0006] The front lens group includes a first positive meniscus lens and a first biconvex lens arranged sequentially from the object side to the image side.

[0007] The rear lens group includes: a first biconcave lens, a second biconvex lens, a second positive meniscus lens, a first negative meniscus lens, a second biconcave lens, and a first filter, arranged sequentially from the object side to the image side.

[0008] Optionally, the air gap between the front lens group and the rear lens group is 1.82mm-2.58mm.

[0009] Optionally, the air gap between the front lens group and the aperture stop is 0.37mm-0.63mm.

[0010] Optionally, the air gap between the aperture and the rear lens group is 1.45mm-1.95mm.

[0011] Optionally, the air gap between the first positive meniscus lens and the first biconvex lens is 0.37mm-0.63mm.

[0012] Optionally, the air gap between the first biconcave lens and the second biconvex lens is 5.6mm-11.2mm; the air gap between the second biconvex lens and the second positive meniscus lens is 6.2mm-11.8mm; the air gap between the second positive meniscus lens and the first negative meniscus lens is 1.8mm-2.6mm; the air gap between the first negative meniscus lens and the second biconcave lens is 0.8mm-1.2mm; and the air gap between the second biconcave lens and the first filter is 1.8mm-2.6mm.

[0013] Optionally, both the first positive meniscus lens and the first biconvex lens are spherical lenses.

[0014] Optionally, the first biconcave lens, the second biconvex lens, the second positive meniscus lens, the first negative meniscus lens, the second biconcave lens, and the first filter are all spherical lenses.

[0015] Optionally, the optical lens has an optical transfer function greater than 0.4 at a half field of view of 7° and a spatial frequency of 100 lp / mm.

[0016] Optionally, the optical lens has a relative distortion value of less than 0.05% at a half field of view of 7°.

[0017] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention provides a large dynamic range star sensor optical lens, which reduces the number of lenses used in the front lens group and reduces the difficulty of aberration correction in the rear lens group by cooperating with multiple positive and negative meniscus lenses and multiple concave and convex lenses, thereby achieving miniaturization and weight reduction of the lens.

[0019] 2. The optical lens for a large dynamic range star sensor provided by the present invention has the characteristics of circular spot, large relative aperture, low chromatic aberration, low distortion, high resolution, small deviation in spot shape and energy after defocusing in each field of view.

[0020] 3. The optical lens for a large dynamic range star sensor provided by the present invention can achieve high-precision extraction of the observed object by the optical lens for a large dynamic range star sensor. This beneficial effect has a guiding role in improving the accuracy of star sensors. Attached Figure Description

[0021] Figure 1This is a schematic diagram illustrating the composition of the optical lens of the present invention;

[0022] Figure 2 This is a graph showing the optical transfer function of the optical lens of the present invention;

[0023] Figure 3 The field curvature diagram and distortion diagram of the optical lens of the present invention are shown.

[0024] Figure 4 This is a diagram showing the defocusing points of the optical lens of the present invention;

[0025] Figure 5 This is a dot diagram of the optical lens of the present invention after defocusing;

[0026] Figure 6 This is a chromatic aberration diagram of the optical lens of the present invention. Detailed Implementation

[0027] The following will be combined with the appendix Figures 1-6 The technical content, structural features, objectives and effects of the present invention will be described in detail through preferred embodiments.

[0028] It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions. They are only used to facilitate and clarify the purpose of illustrating the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationship, or adjustments to the size should still fall within the scope of the technical content disclosed in the present invention, provided that they do not affect the effects and objectives that the present invention can produce.

[0029] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for 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. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] This invention provides a large dynamic range star sensor optical lens, such as... Figure 1 As shown, the optical lens of this large dynamic range star sensor includes: a front lens group 10, an aperture 80, a rear lens group 20, and an image plane 90 arranged sequentially from the object side to the image side, i.e., from left to right in the diagram. The front lens group 10 is the part closest to the object side in the optical system and has the function of collecting light, correcting aberrations, and forming an intermediate image; the aperture 80 is used to control the light flux, which can be achieved by adjusting the relative aperture of the aperture 80; the rear lens group 20 has the function of magnifying the intermediate image, further correcting aberrations, and forming the final image; the image plane 90 is used for optical imaging.

[0032] The air gap between the front lens group 10 and the rear lens group 20 is 1.82mm-2.58mm. Further, the air gap between the front lens group 10 and the aperture 80 is 0.37mm-0.63mm; and the air gap between the aperture 80 and the rear lens group 20 is 1.45mm-1.95mm.

[0033] The front lens group 10 includes: a first positive meniscus lens 31, which is the lens closest to the object side and has the function of collecting light and forming a preliminary image; and a first biconvex lens 71, which is disposed between the first positive meniscus lens 31 and the aperture stop 80 and has the function of adjusting the optical path and optimizing aberrations.

[0034] The air gap between the first positive meniscus lens 31 and the first biconvex lens 71 is 0.37mm-0.63mm.

[0035] In a specific embodiment of the present invention, both the first positive meniscus lens 31 and the first biconvex lens 71 are spherical lenses. Further, the spherical lens is a high-transmittance spherical glass lens. Preferably, the spherical lens of the present invention is made of fused silica and ZF6 glass materials, and without coating, the average transmittance of the optical system is higher than 75%.

[0036] The rear lens group 20 includes: a first biconcave lens 61 disposed on the side of the aperture stop 80 away from the object side; a second biconvex lens 72 disposed on the side of the first biconcave lens 61 away from the object side; a second positive meniscus lens 32 disposed on the side of the second biconvex lens 72 away from the object side; a first negative meniscus lens 41 disposed on the side of the second positive meniscus lens 32 away from the object side; a second biconcave lens 62 disposed on the side of the first negative meniscus lens 41 away from the object side; and a first filter 51 disposed on the side of the second biconcave lens 62 away from the object side to control light intensity. Therefore, from the aperture stop 80 to the image plane 90, the first biconcave lens 61, the second biconvex lens 72, the second positive meniscus lens 32, the first negative meniscus lens 41, the second biconcave lens 62, and the first filter 51 are sequentially arranged.

[0037] The air gap between the first biconcave lens 61 and the second biconvex lens 72 is 5.6mm-11.2mm; the air gap between the second biconvex lens 72 and the second positive meniscus lens 32 is 6.2mm-11.8mm; the air gap between the second positive meniscus lens 32 and the first negative meniscus lens 41 is 1.8mm-2.6mm; the air gap between the first negative meniscus lens 41 and the second biconcave lens 62 is 0.8mm-1.2mm; and the air gap between the second biconcave lens 62 and the first filter 51 is 1.8mm-2.6mm.

[0038] In a specific embodiment of the present invention, the first biconcave lens 61, the second biconvex lens 72, the second positive meniscus lens 32, the first negative meniscus lens 41, the second biconcave lens 62, and the first filter 51 are all spherical lenses. Furthermore, the spherical lens is a high-transmittance spherical glass lens. Preferably, the spherical lens of the present invention is made of fused silica and ZF6 glass materials, and without coating, the average transmittance of the optical system is higher than 75%.

[0039] In a more specific embodiment, the air gap between the front lens group 10 and the rear lens group 20 is 2.2 mm. The air gap between the front lens group 10 and the aperture stop 80 is 0.5 mm; the air gap between the aperture stop 80 and the rear lens group 20 is 1.7 mm. Furthermore, the air gap between the first positive meniscus lens 31 and the first biconvex lens 71 is 0.5 mm; the air gap between the first biconvex lens 71 and the aperture stop 80 is 0.5 mm; the air gap between the aperture stop 80 and the first biconcave lens 61 is 1.7 mm; the air gap between the first biconcave lens 61 and the second biconvex lens 72 is 8.4 mm; the air gap between the second biconvex lens 72 and the second positive meniscus lens 32 is 9.0 mm; the air gap between the second positive meniscus lens 32 and the first negative meniscus lens 41 is 2.2 mm; the air gap between the first negative meniscus lens 41 and the second biconcave lens 62 is 1.0 mm; and the air gap between the second biconcave lens 62 and the first filter 51 is 2.2 mm.

[0040] like Figure 2 As shown, the optical transfer function (MTF) of the large dynamic range star sensor optical lens is greater than 0.4 at a half field of view of 7° and a spatial frequency of 100 lp / mm.

[0041] like Figure 3 The figures show the field curvature and relative distortion values ​​of the optical lens for the large dynamic range star sensor. In the field curvature graph on the left, the vertical axis represents the half-field-of-view angle range, and the horizontal axis represents the field curvature value, showing that the field curvature value of the optical lens for the large dynamic range star sensor is less than 0.08 mm. In the relative distortion graph on the right, the vertical axis represents the half-field-of-view angle range, and the horizontal axis represents the percentage of relative distortion, showing that the absolute value of the relative distortion of the optical lens for the large dynamic range star sensor does not exceed 0.05%.

[0042] like Figure 4 and Figure 5 The image shown is a dot plot of the large dynamic range star sensor optical lens before and after defocusing. Before defocusing, the RMS (Representative Minimum Saturation) of the spot radius in different fields of view is less than 6 μm, and after defocusing, the RMS of the spot radius in different fields of view is less than 10 μm. Calculations show that the average change in RMS of the spot radius after defocusing compared to before defocusing is less than 47%. Therefore, the circularity of the image spot of the large dynamic range star sensor optical lens is excellent both before and after defocusing.

[0043] like Figure 6 As shown, this is a chromatic aberration diagram of the optical lens of the large dynamic range star sensor. The vertical axis represents the half-field-of-view angle range, and the horizontal axis represents the chromatic aberration value. It shows that the absolute value of the chromatic aberration of the optical lens of the large dynamic range star sensor does not exceed 0.5μm at a half-field-of-view of 7°.

[0044] In summary, the large dynamic range star sensor optical lens has the characteristics of optical transfer function greater than 0.4 in each field of view, relative distortion value less than 0.05%, good circularity of the image spot before and after defocusing, and small chromatic aberration. Furthermore, the global surface lens setting provides conditions for the mass production of this large dynamic range star sensor optical lens.

[0045] In addition, the large dynamic range star sensor optical lens has the following optical specifications:

[0046] 1) Large relative aperture: D / f′=1 / 2, where D is the entrance pupil diameter of the lens and f′ is the focal length of the lens;

[0047] 2) Field of view: 2ω = 14 o ， Where ω is the half field of view angle;

[0048] 3) Spectral range: 600nm-1000nm;

[0049] 4) Resolution: Achieve imaging quality comparable to a 2 / 3-inch SmartSens 350 detector (3 megapixels, 4.2μm pixel imaging).

[0050] In summary, the large dynamic range star sensor optical lens provided by this invention has excellent performance such as circular spot, large relative aperture, low chromatic aberration, low distortion, high resolution, small deviation in spot shape and energy after defocusing in various fields of view; it can be used with various 2 / 3-inch high-definition megapixel detectors of different aspect ratios such as 16:9 and 5:4; and it can also achieve the goal of low cost and mass production.

[0051] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A large dynamic range star sensor optical lens, characterized in that, The optical lens consists of a front lens group (10), an aperture (80), a rear lens group (20), and an image plane (90) arranged sequentially from the object side to the image side; the front lens group (10) collects light, corrects aberrations, and forms an intermediate image; the aperture (80) controls the light throughput by adjusting its relative aperture; the rear lens group (20) magnifies the intermediate image, corrects aberrations, and forms the final image; the image plane (90) performs optical imaging on the final image; The front lens group (10) consists of a first positive meniscus lens (31) and a first biconvex lens (71) arranged sequentially from the object side to the image side; The rear lens group (20) consists of a first biconcave lens (61), a second biconvex lens (72), a second positive meniscus lens (32), a first negative meniscus lens (41), a second biconcave lens (62), and a first filter (51) arranged sequentially from the object side to the image side. The air gap between the front lens group (10) and the rear lens group (20) is 1.82mm-2.58mm; The air gap between the first positive meniscus lens (31) and the first biconvex lens (71) is 0.37mm-0.63mm; The air gap between the first biconcave lens (61) and the second biconvex lens (72) is 5.6mm-11.2mm; the air gap between the second biconvex lens (72) and the second positive meniscus lens (32) is 6.2mm-11.8mm; the air gap between the second positive meniscus lens (32) and the first negative meniscus lens (41) is 1.8mm-2.6mm; the air gap between the first negative meniscus lens (41) and the second biconcave lens (62) is 0.8mm-1.2mm; and the air gap between the second biconcave lens (62) and the first filter (51) is 1.8mm-2.6mm. The first positive meniscus lens (31) bends toward the object side; the second positive meniscus lens (32) bends toward the object side; and the first negative meniscus lens (41) bends toward the image side.

2. The large dynamic range star sensor optical lens as described in claim 1, characterized in that, The air gap between the front lens group (10) and the aperture (80) is 0.37mm-0.63mm.

3. The large dynamic range star sensor optical lens as described in claim 2, characterized in that, The air gap between the aperture (80) and the rear lens group (20) is 1.45mm-1.95mm.

4. The large dynamic range star sensor optical lens as described in claim 1, characterized in that, Both the first positive meniscus lens (31) and the first biconvex lens (71) are spherical lenses.

5. The large dynamic range star sensor optical lens as described in claim 1, characterized in that, The first biconcave lens (61), the second biconvex lens (72), the second positive meniscus lens (32), the first negative meniscus lens (41), the second biconcave lens (62), and the first filter (51) are all spherical lenses.

6. The large dynamic range star sensor optical lens as described in claim 1, characterized in that, The optical lens described above has an optical transfer function greater than 0.4 at a half field of view of 7° and a spatial frequency of 100 lp / mm.

7. The large dynamic range star sensor optical lens as described in claim 1, characterized in that, The optical lens described above has a relative distortion value of less than 0.05% at a half field of view of 7°.

Images