The curved prisms have been widely used as a light splitting element because of its own focal power and can be set in nonparallel light path. When the effective light transmission area of large-size curved prism is rectangular or elliptical, it can be processed into rectangular optical elements during processing, which can reduce the volume and mass of the instrument on the one hand, and effectively block the stray light outside the field of view on the other hand. Adhesive fixation is one of the common fixation methods of optical elements, which is applied in many launched spaceborne remote sensors. However, the adhesive bonding process and adhesive strength are unstable and the bonding reliability is poor, resulting in the calculated theoretical bonding area and adhesive layer thickness are often difficult to meet the requirements of complex mechanical and thermal environment. The rigid-flexible dual mode coupling support structure for space-based rectangular curved prism was firstly introduced. And then the tensile and shear tests on the epoxy adhesive used in this project was carried out and the bonding area based on the strength test was designed. On this basis, the mechanical test of the simulator mirror group was carried out to verify the reliability of the bonding area and the design of the support structure. Finally, three bonding postures were simulated analysis and tests including prone, lateral and vertical bonding. The results showed that the vertical bonding was the smallest surface shape errors of the curved prism. Based on this bonding attitude, the bonding and mechanical tests of the curved prism were completed to verify the reliability and rationality of the bonding process.
With the increasing demand of infrared detection, the infrared cold optical technology has developed rapidly in recent decades. The low temperature deformation of infrared optical elements is one of the key factors restricting the development of infrared cold optical technology. The processing and assembly of optical subassemblies and support structures are carried out at room temperature and pressure, while the actual working environment of infrared system is relatively low temperature environment, which can vary by 200 degrees Kelvin or more. Therefore, the temperature adaptability of the support structure is strictly required. The optimal design flexible support of the 70mm diameter single crystal lens made by germanium was carried out to ensure that the component surface shape reached (1/6) λ and the natural frequency was above 200HZ at 100K low temperature in this paper. At the same time, the ISIGHT integrated optimization method was used to optimize the flexible support structure. The multi-objective integrated optimization of key dimensions of flexible support was completed, aiming at maximizing the fundamental frequency of the system and minimizing the lens surface shape errors. Finally, the optimal size was selected to complete the flexible structure design. In this paper, an adaptive flexible support structure for cold optical lens with three layers of stress release was designed by multi-objective integrated optimization method. Meanwhile, its performance was verified by low temperature tests. The results verified the reliability and the feasibility of the structure design and analysis.
The research on optical-mechanical system based on additive manufacturing is based on additive manufacturing, diamond turning, high-precision magnetorheological polishing, surface modification technology, internal lattice structure topology optimization and so on. It can overcome the problems of adhesive use and material matching in the traditional structure design, greatly reduce the difficulty of assembly and thermal control, and realize the lightweight design of internal structure that can not be realized by traditional processing methods. In addition, because the mirror body and its supporting structure are made of same metal materials and integrated, the strength and stiffness are greatly improved compared with the traditional design method. This paper summarizes the development status and technical parameters of additive manufacturing opto-mechanical system at home and abroad. The research progress of surface modification technology by domestic and foreign scholars was focused and the post-processing process and core technologies of the optical-mechanical system were described.
In recent years, the commercialized low-cost rotor UAV equipped with small hyperspectral camera has become an emerging way to acquire hyperspectral remote sensing data due to its advantages of convenient data acquisition and low cost, and has been widely used in environmental monitoring, precision agriculture, ocean development and other fields. Due to its light weight, the flight process of the rotor UAV is vulnerable to the influence of air flow, which leads to the poor stability of the platform and resulting in the geometric distortion of the imaging. This situation is particularly prominent in the obvious air flow areas such as the lake and the sea, which restricts the application in related fields. In this paper, the geometric processing of UAV-borne hyperspectral measured data collected at a wharf in Qiandao Lake is studied. There are two major factors lead to geometric error. One is the longitude and latitude step error, the other is the frame frequency of the navigation data is lower than the image exposure frame frequency. In this situation, this paper proposes a step fitting method to perform geometric correction and error correction for the hyperspectral airstrip data. Compared with the traditional Kalman filtering method and the global linear fitting method, the proposed method can better correct the geometric distortion of hyperspectral image caused by the low-precision GPS/INS system, which provides a foundation for the subsequent quantitative application of lightweight UAV hyperspectral camera in various fields.
Coastal environmental elements such as bathymetry maps are of great significance to the economic and military development of each country. Spaceborne hyperspectral imager is one of the important instruments for coastal zone monitoring. Firstly, this paper systematically reviews the index system of spaceborne hyperspectral imagers, and then introduces the applications of hyperspectral remote sensing images in the retrieval of nearshore bathymetry. In order to improve the inversion accuracy, the current research status and shortcomings of fusion technology of laser active remote sensing and hyperspectral passive remote sensing are discussed. Furthermore, the index system of hyperspectral imagers is prospected based on the requirement of applications in coastal zone monitoring, which provides reference and support for the further development of hyperspectral remote sensing in coastal applications.
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