High-precision small-sized star sensor coaxial transmission optical system

Abstract

High-precision small star sensor coaxial transmission type optical system relates to the technical field of optical system, in order to solve the problem of large distortion value of the existing star sensor optical system, and then affect the imaging quality, the optical system of the present application adopts coaxial transmission type structure, the imaging spectrum is 450nm to 850nm;The optical system comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along the optical axis;It also includes a diaphragm surface between the third lens and the fourth lens;The first lens, the third lens, the fifth lens and the sixth lens are positive lenses, and the second lens, the fourth lens and the seventh lens are negative lenses;The F number of the optical system of the present application is low, the light quantity of the optical system can be improved, and the image brightness is increased. The number of lenses is small, the structure is simple, and the cost is controlled and optimized, which can significantly save cost and space.

Description

TECHNICAL FIELD

[0001] The utility model relates to optical system technical field, concretely relates to high accuracy small -size star sensor coaxial transmission type optical system. BACKGROUND

[0002] Star sensor as the leading attitude sensor of measurement precision in the control system of spacecraft, has the irreplaceable importance for satellite attitude control. With the rapid progress of microsatellite technology, especially the wide application of autonomous navigation star sensor, the market demand of star sensor is developing towards large field of view, lightweight design and higher precision. The key technologies of star sensor on the current market cover the research and development of optical system, advanced image processing algorithm and accurate star map matching technology.

[0003] However, in the design of the core component (optical system) of star sensor, although certain achievements have been made, there are still significant challenges and defects. Specifically, the optical system needs to meet the following characteristics: (1) for star point target imaging, although details are not pursued, the position of the image point mass center must be ensured to be highly accurate; (2) the center error of the dispersion spot energy of each spectral segment is strictly controlled, usually not more than one tenth of the pixel size, to ensure the accuracy of measurement; (3) on the basis of ensuring imaging quality, the number of optical elements is simplified to facilitate processing and assembly, and the axial and radial dimensions of the lens are reduced as much as possible to reduce the overall volume and weight of the star sensor.

[0004] The current market star sensor optical system design scheme is various, including a double Gauss structure non-imaging telecentric system composed of nine spherical lenses, a non-imaging telecentric system composed of seven non-cemented spherical lenses, and a non-cemented imaging telecentric system. However, these systems generally have a key problem: large distortion value, which directly affects the imaging quality and limits the performance of the star sensor in the field of high-precision measurement. Therefore, how to effectively reduce distortion while maintaining lightweight and large field of view design and improve imaging quality has become a technical bottleneck that needs to be broken through in the research and development of the current star sensor optical system.

[0005] In order to overcome the above-mentioned technical problems, the utility model provides a kind of high-precision small star sensor coaxial transmission type optical system, by reasonable selection structure and material, make optical system satisfy large field of view, wide spectrum, low distortion and light small type requirement. Utility model content

[0006] The utility model provides a kind of high-precision small star sensor coaxial transmission type optical system to solve the problem of large distortion value of the existing star sensor optical system, which affects the imaging quality.

[0007] A high-precision small star sensor coaxial transmission type optical system, the optical system adopts a coaxial transmission type structure, and an imaging spectrum range is between 450nm and 850nm;The optical system comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along an optical axis direction;And a diaphragm surface is arranged between the third lens and the fourth lens;The first lens, the third lens, the fifth lens and the sixth lens are positive lenses, and the second lens, the fourth lens and the seventh lens are negative lenses.

[0008] The high-precision small star sensor coaxial transmission type optical system has the advantages that:

[0009] 1、The spectrum range of the optical system is between 450nm and 850nm, and the optical system can be used for splicing a wide spectrum range detector;

[0010] 2、The optical system has a low F number, can improve the light amount of the optical system, and increase the image brightness;

[0011] 3、The optical system has a small number of lenses, a simple structure, and cost control and optimization, so that the cost and space can be significantly saved;

[0012] 4、The optical system is repeatedly optimized and designed by using optical design software according to the basic imaging optical principle, so that high-quality image output can be realized, and the recognition precision is improved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a structure schematic view of the high-precision small star sensor coaxial transmission type optical system;

[0014] Figure 2 It is a spot diagram of the high-precision small star sensor coaxial transmission type optical system at 20 DEG C.

[0015] Figure 3 It is an energy concentration degree curve of the high-precision small star sensor coaxial transmission type optical system;

[0016] Figure 4 It is a distortion diagram of the high-precision small star sensor coaxial transmission type optical system at 20 DEG C.

[0017] Figure 5 It is a vertical axis chromatic aberration diagram of the high-precision small star sensor coaxial transmission type optical system at 20 DEG C.

[0018] In the drawing:

[0019] 1, first lens, 2, second lens, 3, third lens, 4, fourth lens, 5, fifth lens, 6, sixth lens, 7, seventh lens, 8, diaphragm plane. DETAILED DESCRIPTION

[0020] In combination Figures 1 to 5 The embodiment is described, high-precision small star sensor coaxial transmission type optical system, in the optical system, along the optical axis direction sequentially arranged on the same optical axis of the first lens 1, second lens 2, third lens 3, fourth lens 4, fifth lens 5, sixth lens 6 and seventh lens 7, the optical system also includes the diaphragm plane 8 between the third lens 3 and the fourth lens 4. Among them, the first lens 1, the third lens 3, the fifth lens 5 and the sixth lens 6 are positive lens, the second lens 2, the fourth lens 4 and the seventh lens 7 are negative lens.

[0021] The material of the first lens 1 is SILICA, the curvature radius of the front and back surface is 20mm-30mm and-40mm-50mm respectively, the thickness is 3mm-5mm, the distance between the first lens 1 and the second lens 2 is 1mm-2mm. The material of the second lens 2 is H-ZLAF89L, the curvature radius of the front and back surface is-60mm-70mm and-100mm-105mm respectively, the thickness is 3mm-4mm, the distance between the second lens 2 and the third lens 3 is 2mm-3mm. The material of the third lens 3 is H-ZK3, the curvature radius of the front and back surface is 10mm-20mm and-100mm-130mm respectively, the thickness is 2mm-3mm, the distance between the third lens 3 and the fourth lens 4 is 1mm-2.5mm. The material of the fourth lens 4 is H-TF5, the curvature radius of the front and back surface is-35mm-45mm and 5mm-10mm respectively, the thickness is 0.8mm-2mm, the distance between the fourth lens 4 and the fifth lens 5 is 1mm-2.5mm. The material of the fifth lens 5 is H-FK55, the curvature radius of the front and back surface is-5mm-15mm and-300mm-400mm respectively, the thickness is 2mm-4mm, the distance between the fifth lens 5 and the sixth lens 6 is 3mm-5mm.

[0022] The material of the sixth lens 6 is H-ZLAF89L, the curvature radius of the front and back surface is 15mm-20mm and-80mm-100mm respectively, the thickness is 3mm-4mm, the distance between the sixth lens 6 and the seventh lens 7 is 1mm-2mm. The material of the seventh lens 7 is H-ZF52, the curvature radius of the front and back surface is-15mm-20mm and 20mm-27mm respectively, the thickness is 2mm-4mm, the distance between the seventh lens 6 and the image plane is 2mm-3mm. Table 1 is the parameter of the optical system.

[0023] Table 1

[0024]

[0025] In the embodiment, the air gap between the diaphragm 8 and the fourth lens 4 is between 1mm and 2mm.

[0026] In the embodiment, the refractive index of the first lens 1 is between 1.45 and 1.46; the refractive index of the second lens 2 is between 1.95 and 1.96; the refractive index of the third lens 3 is between 1.57 and 1.58; the refractive index of the fourth lens 4 is between 1.65 and 1.67; the refractive index of the fifth lens 5 is between 1.55 and 1.56; the refractive index of the sixth lens 6 is between 1.95 and 1.96; and the refractive index of the seventh lens 7 is between 1.84 and 1.85.

[0027] The imaging spectrum of the embodiment of the utility model is 450nm to 850nm, the F number of the optical system is between 1.2 and 1.6, the star sensor optical system adopts coaxial transmission type structure form, the system focal length is 19mm, the full field of view is 21 DEG, the entrance pupil diameter is Φ14.615mm, the optical total length is 34mm, and the structure is relatively compact. The optical system has the characteristics of large field of view, wide spectrum, low distortion and light and small type, is suitable for attitude measurement of small spacecraft such as micro-nano satellite, and can significantly improve the attitude determination precision and stability of satellite.

[0028] As shown in Figures 2 to 5 , in the embodiment, the roundness of the light spot in the whole field of view range is good, the imaging is uniform, and the RMS radius of each field of view is about one pixel, and the difference of the RMS radius of the diffused circle in the full field of view range is small. As shown in Figure 3 , the off-axis field of view in Figure 3 has the same diffused spot energy concentration curve as the on-axis field of view, and both are greater than 89% in the range of 10.35μm (3x3 pixels), and the imaging quality is excellent. As shown in Figure 4 , the optical distortion can be optimized to within 0.1%, meeting the requirements of imaging quality. As shown in Figure 5 , the maximum off-axis chromatic aberration in the full field of view range is 2.31μm, meeting the requirements of imaging quality.

[0029] The technical features of the above embodiments can be combined arbitrarily, and to make the description concise, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0030] The above-described embodiments only express several implementation manners of the utility model, the description is more specific and detailed, but can not therefore be understood as the limitation of the utility model patent range. It should be pointed out that for ordinary skilled person in the art, without departing from the utility model concept, several modifications and improvements can be made, which belong to the protection range of the utility model. Therefore, the protection range of the utility model patent should be subject to the appended claims.

Claims

1. A high-precision, miniature star sensor coaxial transmission optical system, characterized by: The optical system adopts coaxial transmission structure, and imaging spectrum is 450nm to 850nm; the optical system comprises first lens (1), second lens (2), third lens (3), fourth lens (4), fifth lens (5), sixth lens (6) and seventh lens (7) arranged in sequence along the optical axis direction; further comprising diaphragm surface (8) between third lens (3) and fourth lens (4); The light beam is received by the image surface after passing through first lens (1), second lens (2), third lens (3), diaphragm surface (8), fourth lens (4), fifth lens (5), sixth lens (6) and seventh lens (7) in sequence; The first lens (1), third lens (3), fifth lens (5) and sixth lens (6) are positive lenses, and the second lens (2), fourth lens (4) and seventh lens (7) are negative lenses.

2. The coaxial transmissive optical system of the high-precision small-size star sensor according to claim 1, characterized in that: The material of the first lens (1) is SILICA, the material of the second lens (2) is H-ZLAF89L, the material of the third lens (3) is H-ZK3, the material of the fourth lens (4) is H-TF5, the material of the fifth lens (5) is H-FK55, the material of the sixth lens (6) is H-ZLAF89L, and the material of the seventh lens (7) is H-ZF52.

3. The coaxial transmissive optical system of the high-precision small-size star sensor according to claim 1, characterized in that: The curvature radii of the front and back surfaces of the first lens (1) are 20mm-30mm and-40mm-50mm respectively, and the thickness is 3mm-5mm; The curvature radii of the front and back surfaces of the second lens (2) are-60mm-70mm and-100mm-105mm respectively, and the thickness is 3mm-4mm; The curvature radii of the front and back surfaces of the third lens (3) are 10mm-20mm and-100mm-130mm respectively, and the thickness is 2mm-3mm; The curvature radii of the front and back surfaces of the fourth lens (4) are-35mm-45mm and 5mm-10mm respectively, and the thickness is 0.8mm-2mm; The curvature radii of the front and back surfaces of the fifth lens (5) are-5mm-15mm and-300mm-400mm respectively, and the thickness is 2mm-4mm; The curvature radii of the front and back surfaces of the sixth lens (6) are 15mm-20mm and-80mm-100mm respectively, and the thickness is 3mm-4mm; The curvature radii of the front and back surfaces of the seventh lens (7) are-15mm-20mm and 20mm-27mm respectively, and the thickness is 2mm-4mm.

4. The coaxial transmissive optical system of the high-precision small-size star sensor according to claim 1, characterized in that: The distance between the first lens (1) and the second lens (2) is 1mm-2mm; the distance between the second lens (2) and the third lens (3) is 2mm-3mm; the distance between the third lens (3) and the fourth lens (4) is 1mm-2.5mm; the distance between the fourth lens (4) and the fifth lens (5) is 1mm-2.5mm; the distance between the fifth lens (5) and the sixth lens (6) is 3mm-5mm; the distance between the sixth lens (6) and the seventh lens (7) is 1mm-2mm; and the distance between the seventh lens (7) and the image plane is 2mm-3mm.

5. The coaxial transmissive optical system of the high-precision small-size star sensor according to claim 1, characterized in that: The air gap between the diaphragm plane (8) and the fourth lens (4) is 1mm-2mm.

6. The coaxial transmissive optical system of the high-precision small-size star sensor according to claim 1, characterized in that: The refractive index of the first lens (1) is 1.45-1.46; the refractive index of the second lens (2) is 1.95-1.96; the refractive index of the third lens (3) is 1.57-1.58; the refractive index of the fourth lens (4) is 1.65-1.67; the refractive index of the fifth lens (5) is 1.55-1.56; the refractive index of the sixth lens (6) is 1.95-1.96; and the refractive index of the seventh lens (7) is 1.84-1.

85.

7. The high-precision small-size star sensor coaxial transmission optical system according to claim 1, characterized in that: The F number of the optical system is 1.2-1.

6.

8. The coaxial transmissive optical system of the high-precision small-size star sensor according to claim 1, characterized in that: The focal length of the optical system is 19mm, the full field of view is 21°, the entrance pupil diameter is Φ14.615mm, and the total optical length is 34mm.

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