Design of Off-Axis Two Reflecting System for Parallelism Calibration of Two Axes

A new optical system is designed to calibrate the two-optical axis parallelism between visible light and 1.06μm laser. The common optical path was composed of a high-order paraboloid reflector and a secondary hyperboloid reflector. A reflecting mirror and a beam splitter were installed behind the secondary mirror to separate, reflect the lights and compress volume. Halogen lamp with 1mm diameter aperture and ZnS glass was used to provide uniform illumination for calibration system. The MTF of common optical path system at 110 lp/ mm is greater than 0.3 in the visible light, which is also no less than 0.1 in the laser band. The length of common optical system is about one third of its effective focal length. The maximum distortion of axial calibration objective lens is less than 0.05% in full field of view. The design results show that the calibration system has advantages such as compact structure and small size, whose imaging quality achieves the diffraction limit at transmission and reflection of path in full band.