数显式自准直仪使用时,气流等环境条件的影响以及仪器本身发热等原因都会引起示值的漂移和跳动,使测量误差增大、测量结果不能回零。采用增加一块固定反光镜作为参考镜,它与工作反光镜以自准直仪进行差动,组成自校准系统,可以有效地进行消减。仅用工作反光镜时2h内的漂移量为0.03″,经自校准系统后为0.01″;样本标准偏差为0.091 1″,经自校准后为0.057 4″。差动式反光镜自校准系统可以显著减小CCD自准直仪的示值漂移,对减小示值跳动也具有一定作用。且无论是对环境条件还是仪器本身原因引起的漂移和跳动都是有效的。

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.