This paper designs an integrated optical system for detection and recognition. The system combines the R-C (Ritchey-Chretien optics) system and the zoom structure. The R-C mirror design of the initial structure of the system is completed by calculation of theory. Then, use the zoom theory to complete the design of the two zoom positions. The two zoom positions respectively realize the detection and identification of space debris. The F numbers are 5.86 and 11. The field of view angles are 2.83°and 0.6°. It works in band of 400-750nm. The system has an entrance pupil diameter of 300mm. The detection position can detect space debris with a brightness of 13 magnitude stars, with focal length of 1760mm; the recognition position’s modulation transfer function is greater than 0.6 at the Nyquist frequency of 33.33lp/mm, with the focal length of 3300mm. The zoom theory is well applied in the integrated detection and recognition system.
In order to deal with the threat of space debris to space experiment platforms and equipment, three-mirror anastigmatic system, which has the characteristics of light weight, small size and good optical performance, are used for space debris detection and detailed imaging. With the development of freeform surfaces, this article shows a new type of structure which has good optical performance and simple complexity of assembly and adjustment. The first step is to analyze the calculation method of the initial structure parameters of TMA system, and then the secondary mirror adopts the XY polynomial freeform surface. The primary mirror is reused as tertiary mirror, and the design of a new type TMA system is finally completed. Its effective focal length is 400 mm, the field of view (FOV) is 2°×4°, F/# is 5. At the Nyquist frequency 108lp/mm, the MTF value of this system is greater than 0.588. The maximum distortion is less than 0.80%. The results show that the imaging quality of the system meets the design requirements in the effective field of view.
At present, the frequency of human space activities continues to increase, resulting in more and more space debris, which poses a great threat to the working satellite. The collision of debris and satellites may cause abnormal operation of the satellite or even complete damage. Based on the 3u cubic satellite platform, this paper has designed a miniaturized visible light detection system with a full field of view of 12° (9°×7°). the wavelength band of the system is 450 ~ 800nm, the pixel size of the detector is 5μm, the entrance pupil diameter is 60mm, the system focal length is 150mm, the detection system is composed of 8 lenses. Using optical design software to evaluate the image quality of the optical system, the results show that the diffusion spots in each field of view are approximately circular, the maximum RMS radius is less than 7.4 μm, and the energy distribution in each field of view is more than 80% within 3 × 3 pixels, field curvature, distortion all meet the requirements of the detection system. Finally, the tolerance analysis results show that the design has good imaging quality and meets the system performance requirements and machining requirements. The visible light detection system has a large field of view, light weight, low processing cost and high energy concentration. and can meet the demand for space debris detection in Earth orbit.
In the process of restoring the image of space optical camera, it is necessary to use the standard 24 color card to correct the image. In order to improve the accuracy of the mapping function in the process of color correction and prevent the occurrence of overfitting at the same time, a neural network correction method with comprehensive objective function is proposed. Using the idea of regularization as a reference, a constraint term with smooth performance is added to the objective function of the neural network to improve the generalization ability of the network map to data. The experimental results on the dataset of the real color card of the space camera sho-ore the correction.
With the rapidly development of optoelectronic technology and computer technology, the projection display technology has also been unprecedentedly developed. In this paper, a zoom projection objective lens is designed based on Digital Light Processing (DLP) projection display technology, the 0.47in DMD chip of Texas Instruments is selected in this paper, its resolution is 1920×1080 and its micromirror pitch is 5.4 μm. The optical system uses a 100% offset transmissive projection structure. The working wavelength of the whole zoom projection lens is visible light, and 14 lenses including protective glass are used for the projection lens, each lens in the designed system is spherical, the total length of the system is 220mm, the aperture of the optical system is about 58mm , focal length of the zoom projection lens ranges from 25mm to 32 mm, viewing angle ranges from 41 degree to 51 degree , and F number is 1.7 , the distortion of the designed system is less than 3%, the projected image plane relative illumination of the zoom projection lens above 90% , the telecentricity of the system is less than 1 degree. The MTF value is close to 0.3 at the Nyquist frequency 93 lp/mm for the full field of view, the designed system meet the requirements of projection. In order to meet the current processing level, the radius of curvature tolerance, the spacing tolerance, the eccentricity tolerance and the tilt tolerance are analyzed. The results show that the zoom projection lens is easy to process and produce.
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