Absolute Distance Interferometric Techniques Used in On-Orbit Metrology of Large-Scale Opto-Mechanical Structure

Optical misalignment caused by opto-mechanical structural deformation on account of null-gravity state and on-orbit unsteady-state temperature field becomes more serious with the increased sensor aperture. High-precision optical components distance metrology is demanded to meet the required optical accuracy in on-orbit alignment. Accuracy of submicron in absolute distance is needed, which is limited by the facts of space environment, implementation conditions, system running costs, etc. Aiming at engineering implementation, in this chapter, the researches of on-orbit laser interferometry absolute distance metrology of large-scale opto-mechanical structure were provided as follows: In terms of measuring method, the interferometric technique, double heterodyne interferometer, and its related technology branches are reasonable to acquire the required precision. The technical principle and feasibility was provided. This chapter matched the possible measuring range and the application range of the displacement. The mathematical solution based on the excess fractions was considered to be valuable in terms of an expanded measurement range without additional systematic costs. This chapter also analyzes the main error source. The error control method by means of control measure time was concluded.