1. State Key Lab of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
2. Beijing Aerospace Institute for Metrology and Measurement Technology, Beijing 100076, China
Abstract：When the digital autocollimator is put into use directly, its indications will drift and beat under the influence of environmental conditions such as air streams and the increasing heat of equipment itself, which leads to the measuring errors greatly increased and the measurement results could not return to zero. A fixed mirror which is added as a reference mirror makes the differential measurement with a working mirror and forms a self-calibration system, which could effectively reduce errors. The value of drift is 0.03″ in two hours when working mirror is only used and it reduces to 0.01″ after the adoption of a self-calibration system; the standard deviation of samples is 0.0911″ and it reduces to 0.0574″ after the self-calibration. The self-calibration system of differential mirror could effectively reduce the indication errors of CCD autocollimator and plays an efficient role in reducing the indication beat. It is an effective way for the system to reduce the drift and beat of the equipment caused by both the environmental conditions and the equipment themselves.
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2011, Vol. 32 
