The Alignment And Test Of The Synthetic Aperture Optical System

The synthetic aperture optical system is a new type of Cassegrain optical system, whose main mirror is composed of several sub-aperture mirrors. Sub-aperture stitching technology can help optical system fulfill the requirements of large aperture, light weight and collapsible. The key technology of synthetic aperture optical system is in its alignment and test. As a project of pre-research, a modified Cassegrain system with synthetic aperture is adjusted and tested. The system has a 500mm-aperture main mirror which is composed of eight sub-apertures and one central mirror. The difficulty of the alignment is how to keep the concentricity among the sub-apertures and the central annulus. The ways to test the optical system are also discussed. Without the sub-apertures, we test the synthetic aperture optical system with ZYGO interferometer. Testing results shows that the peak-to-valley (PV) value is 0.235λ, root-mean-square (RMS) value is 0.029λ, which meet the requirements of optical system's imaging quality. The resolution can rearch 681p/mm, tested by CCD camera, which meets the maximum resolution of the camera. The resolution value of the single sub-aperture is 32.242 lp / mm . And the maximum resolution of the optical system is 96.73 lp / mm tested by microscope. The test results meet the requirement of the project indicators.