Design of a novel high precision opto-electronic levelmeter

For currently market available levelmeter can not meet the requirement for measuring the azimuth mounting of the LAMOST, this paper presents a novel design scheme of an opto-electronic levelmeter with needed high precision. The levelmeter is essentially a combination of an optical front end and a computer aided measuring back end. The light from a point source is firstly turned to be parallel and reflected by a tip-tilt mirror which keeps pointing to the zenith and then imaged onto a CCD target through optical system, afterwards, the position of the image spot is processed by computer software to give measurement results. By rotating the LAMOST mounting about azimuth axis with the levelmeter on it, the axis system is measured, and if the measured azimuth axis is not perpendicular enough, the image spot on CCD target is to offset some distance by which the tilt angle of the axis can be evaluated. The design principle and data processing of the levelmeter are detailed systematically in this paper. Experiment results confirmed that the accuracy of the levermeter is up to 0.043" beyond that required by the technical specification of the LAMOST. Also, the novel levermeter is applicable to measuring azimuth axes of other telescopes. 1