With the rapid increase of the number of spacecrafts, the space environment is becoming more and more complex. The demand of spacecraft for omni-directional detection of surrounding objects is becoming more and more urgent. This paper introduces a distributed space objects detection technology based on optical fiber image bundles. The system adopts multi aperture optical system. The optical signal is transmitted to the high-sensitivity image sensor through the fiber image bundle for imaging. Compared with the traditional method, the multi aperture optical system using fiber image bundles can be flexibly arranged according to the needs. The system has the advantages of wide field of view, flexible layout and low cost. This paper introduces the relevant technologies used and the principle prototype developed.
Shortwave laser is more and more widely used in gated imaging, tracking and pointing, communication and other fields. For the requirement of 1550nm high power laser source, The paper analyzes the realization way, and realized the 1550nm high power laser lighting source. We use multichannel semiconductor laser coupling to realize the high-power light source, and uses fiber coupling to realize the uniform spot. On this basis, an extended collimator is designed, which achieves 10 times of high-power The beam divergence angle can reach 9 mrad to 90 mrad, and the RMS value can be less than 1/4 of the wavelength at each magnification of the wave phase difference, which can meet the needs of engineering application.
In view of whether the optical system of a focal length 14~360mm continuous zoom TV can obtain high quality and high reliability images in high and low temperature environment, especially in extreme low temperature environment. The thermal design of zoom TV optical-mechanical system using passive thermal control and active thermal control is proposed. The passive thermal control uses polyimide as insulation material to increase the thermal resistance between the camera interior and the outside. Active thermal control uses electric heating film to dynamically heat the key parts of the camera lens. Under the condition of low temperature, the finite element method is used to establish the heat transfer model of the whole lens assembly in the workbench finite element software, and analyze the heat load composition, including the heating power load, the heat convection load and the heat radiation load, and carry on the steady state thermal analysis. Through thermodynamic analysis and experimental verification, the consistency of focal plane of zoom camera optical system is good after taking active thermal control measures at the extreme low temperature of -45°C. The optical transfer function (OTF) of zoom lens at cut-off frequency (100lp/mm) is 0.25 higher than that before thermal design, which can meet the requirements of thermal control design with better transfer function distribution and higher imaging quality. The correctness of the simulation results and the rationality of the optical-mechanical design are verified.
In the light of optical-electronic imaging system ,designed a continuous zoom lens with a optical aperture of 60mm and a zoom range of 18-246mm. Summarized the disadvantages of the former zoom lens and a low temperature resistant and high precision structure ,named the special-shaped slide and cam zoom structure is proposed, and carrying out the theoretical analysis and the detailed structural design. Theoretical analysis shows that this kind of structure can make the sliding friction between the cam and the main mirror tube turned into rolling friction ,thus reducing the torque demand.it also helps to eliminate the stuck phenomenon of the cam in low temperature environment .The special-shaped slide frame structure can help eliminate the tilt Angle of the moving mirror group in the zoom process ,thus reducing the variation of optic axis .In the he final test, the zoom time is not longer than 8s in the environment which temperature is only -45°C,and the variation of optic axis is smaller than 0.3milliradian,both meet the target requirement.
For some extreme environment, such as vibration and shock during rocket launching or ultralow temperature in tank of cryogenic propellant, some key technology of the optical measurement device used in liquid oxygen tank of carrier rocket have been researched. In order to obtain a light-weight, high-stiffness and large-heat resistance main board structure for optical measurement device, a thermo-mechanical topology optimization technique is introduced into the main board structure design of optical measurement device for improving the designing quality. Compared with that before the optimization the main board structure reduces weight loses 46.8 percent with the first-order natural frequency above 420 Hz. The numerical results indicate that after adopting the topologic optimization design method, not only the design course is shortened, but also the main board structure weight is effectively reduced, heat resistance is effectively increased and the capability of the main board structure is enhanced. The extreme temperature test results show that the method is effective.
In order to acquire the geographic location information of sea-surface, aiming at feature that sea-surface elevation is known. A self-location algorithm independent of ranging equipment was developed. The paper uses camera’s position and attitude information measured by position and orientation system which rigid connect with camera. Then the paper compensates the lever arm which comes from GPS Antenna phase center and camera center of photography. So that accuracy position was got. The collinearity equation is built by the camera’s position, attitude and the known sea-surface elevation which equals zero to calculate target geodetic coordinates. The error model is built basing on total differential method. At last the location error of different detection range and angles of strabismus is analysed.
When the aerial camera photograph,a variety of image motion is caused by prior to the flight, pitching, rolling and vibration and other reasons,thus leading to the existence of relative motion of the illuminated objects in the focal plane of a photosensitive medium, the image is blured,and the imaging quality of the camera is seriously affected. Various causes of image motion and effects on image is analyzed by this paper,the necessity of image motion compensation is expounded. By analyzing existed methods of image motion compensation ,and on this basis, a new multi degree of freedom motion compensation method is designed,through the parallel mechanism motion,for image motion compensation by optical image motion compensation principle,a variety of airborne camera to take pictures of the image motion also can be eliminated.
Compared with visible light imaging systems, the infrared imaging systems have the advantages of strong fogging ability, especially in the high-altitude water vapor and haze environment. and the medium-wave infrared cooling detectors have the advantage of low cost compared to long waves. Therefore, in recent years, The demand for medium-wave infrared continuous zoom systems is increasing. In this design, based on the medium-wave infrared optical system, and summarizing the advantages and disadvantages of the previous zoom structure, a zoom mechanism in the form of a cam and guide was proposed. The cam mechanism, zoom guide mechanism, and compensation guide mechanism were described in detail in this paper. The detailed analysis of the torque demand during zooming was performed. Ansys workbench was used to analyze the main components of the zoom mechanism and the stray light of the system was proposed. The adjustment results show that this kind of structure can realize medium-wave infrared continuous zooming, and the the amount of optical axis shaking during zooming is less than 0.3mrad, which meets the design requirements, and the proposed stray light suppression method effectively suppresses the system's spurious radiation and improves the lens's imaging quality; impact and vibration simulation show that the strength and stiffness of the structure meet the requirements of the mechanical environment, and the imaging system has stable performance.
To a high resolution digital camera which works in visible light and is on the space-based platform flying in 500 km orbit, analyzed the principle of image acquisition, established the collinear equation and target location model from the system measured the pose of camera and single image without control points, and researched the method to calculate the geographic coordinate of target point. Analyzed the consisted factors of target location accuracy, and generated the formula for calculating target location accuracy based on the accuracy theory. For the cameras working in this mode, gave the elements of orientation and the parameters of camera, then obtained the target location accuracy is 16.1 meter through the simulation analysis to the model. The analysis to the target location accuracy provides a theoretical base for the practical use of the space camera. Analyzed the impact of the camera parameters and operation mode on the location accuracy, and put forward some measures to improve the target location accuracy.
Thermal control and temperature uniformity are important factors for space remote sensing cameras. This paper describes the problems with existing systems and introduces the thermal design of a space optical remote sensing camera. Firstly, based on the theory of wave-front aberration distribution, the thermal control index of a space remote sensing camera is proposed. Then on the basis of the analysis of the heat flux environment outside the camera space, the thermal optical analysis of the camera is performed by using the finite element analysis method at high and low temperature conditions. The results show that the transfer function of the optical system with the resolution of 50 lp in the full field of view is more than 0.4. The optical design index can be satisfied, and the rationality of the thermal design is verified. The simulation result meets the requirements of optical design very well. Therefore the study in this paper can be used as an important reference for other space optical systems, which has certain engineering significance.
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