Test And Monitor Techniques Of Large Cocave Aspheric Segmented Mirror

In order to improve the resolution and reduce the difficulty of mirror processing, the primary mirror of the next generation space telescopes goes to adopt large calibre segmented mirror in common. Several optical systems whith large calibre and long focal length are designed, in which the reflective optical system with a 3.8m-calibre segmented mirror and 36m-focal length is adopted. The system has a high image quality and accords with the optical manufacture level in the country. This paper propose the dynamic interferometry to test the segmented mirror which suits for domestic condition of optics technology after researching the test techniques of large caliber optical systems in the world and combining the difficultes of testing the asphere mirror with large caliber.After the segmented mirror is stretched and during its operating, there exists phase error between each segment of primary mirror. So co-phasing of segments controlled by the active commanding system in the space environment is the key technique of studying the large space telescope. In this paper, several on-orbit monitor techniques of the space telescope segmented primary mirror in advanced countries are rearched. And based on the optical manufacture development level in the country, this paper put forward a monitor plan adapts to our country. Content of these monitor techniques are given.Monitor technique based on the phasing camera and edge position sensors. According to the information of the segments'pictures collected by the phasing camera, applying the phasing technique to find out the elementary position errors of the segments.Using the edge position sensors to revise the residual position error to 3.75nm.Monitor technique based on the Near Infrared Camera(NIRCam). Disposing the pictures collected by the NIRCam by applying the DFS (dispersed fringe sensing) algorithm and meliorate Gerchberg-Saxton(MGS) algorithm during the coarse phasing step and fine phasing step to obtain the maladjustment information of the segmented mirror. Revise the position error of segments to less than 10nm.Monitor technique based on the dynamic interferometry. Use the dynamic interferometry when monitoring the segmented mirror. Obtain the maladjustment infotmation of the segmented mirror through the interference pattern. The least square algorithm simulation system is designed and realized to real time monitor the segmented mirror which procides evidence for adjusting of all segments into a united focal and phase.