Study On Computer Controlled Manufacturing Technology Of Off-axis Aspherics

Aspheric optical components reduce the size, weight and complexity of optical systems by reducing the number of surfaces required to form unaberrated images, especially for the large aperture space remote sensors. Nowadays, with the increase of civil resource investigation and military requirement, view field and resolving power of the space CCD camera are required more, larger and higher. Taking the most advanced KH-13 space camera as an example, its resolution to the ground can be up to 0.1 meter. We aim the technical characteristics of the wide view camera under developing and manufacturing at the internationally state-of-the-art level. The fabrication of large off-axis aspherics key components in the camera is the important technology that needs us to carry out researches. Through computer controlled optical surfacing (CCOS), the fabrication technology of large size off-axis optics are carried out with home-made aspheric numerical control center and dual-gauge profilometer by absorbing old asperics numerical control technology. In this thesis, the following researches on 3rd ~ff~ axis testing mirror that is key part in the camera are carried out: Tool removal function of small and middle grinding tool under different working modes in CCOS. As the key technology of CCOS, the removal function of small grinding toll decides the efficiency, precision of CCOS fabrication and surface error mode of aspherics. By the comparison of tool removal function under the modes of planet and planar movement, the tool under the mode of planar mode can efficiently overcome middle-frequency error in CCOS technology. Through optimizing design and process testing of the tool under planar mode, the -best matched parameters are decided under the best removal function. I) Defining initial spherical diameter of off-axis aspheric surface. To nearly one-meter off-axis aspherics, it抯 resolved diameter of symmetry parent mirror can be about two meters. It is hard to directly mill the large size aspherics to required surface with current technology. We fabricated the off- axis to best-fitted spherical profile. in the thesis, on the principle of least ~IIIi~ V manufacture remain, the best fitted spherical diameter of off-axis aspheric under the case of few reference. This computation method with wide application is not applied to off-axis aspherics and also to co-axis aspherics. 2) Manufacture of novel dual-gauge profilometer The surface error of aspheric mirror during grinding ranges from tens of microns to a few microns. proper measurement method will decide the convergent speed and precision of the error in this range. In the thesis, a novel low-cost dual-gauge off-axis profilometer is presented through relative measurement principle. Shepard interpolation model is used to process the measuring data to quickly converge the surface error during grinding and realize the transition to visible light interferometer. 3) Design and analysis of null corrector Null compensation testing is common testing method used for high gradient and high precision. Null corrector is the important components in compensation testing. However, such null corrector is very sensitive to alignment error due to difficulty measurement of n...