Research On The Measurement Technology Of The Angular Resolution Of Space Laser Scattering

Measuring the spatial scattering light on the optical element’s surface after ion etching is of great significant, which can obtain micro geometry of the optical element,evaluate the optical properties of optical elements and improve the process of ion etching. So the deep research on the measurement system is made in this paper.Focusing on the technique of beam shaping, the design of the mechanical structure and the technology of related detection, the design scheme of the measurement system is presented after deeply studying the measurement theory on scattering, which is based on the theory of bidirectional reflectance distribution function. The hardware part of the measurement system is mainly composed of three modules as follows, the optical module, the mechanical module and the signal acquisition and control module. In the part of the optical module, the modulation of light source, beam expanding and collimation. spatial filtering of light beam, beam focusing, the change of the incidence angle and the elimination of the stray light are all come true. And for the mechanical module, the measurement range of zenith angle 00～900 and azimuth angle 00～3600 is achieved. In addition, the high precision measurement on the signal of weak spatial scattered light is also successfully realized by the technology of correlation detection in the signal acquisition and control module. In addition to the hardware structure, the Software module,which is developed based on the Lab VIEW, consists of four modules as follows, user login module, test module, reference light scattering measurement module and storage module.With the integration of hardware and software, high precision measurement system is developed finally. And many advantages have been owned for the system in the measurement of the spatial scattering rate of the sample, including high signal-to-noise ratio, high precision and a fast response time, and so on. Based on the experiments of the Scattering rate of sample after ion etching, the influence of the optical module on the accuracy of measurement is analyzed. Furthermore, the error of the measurement system is also analyzed. The results of the experiments show that the precision of measurement system has reached 1O-5 ppm (corresponding to 10-11) when the power of the laser is 1mW.