Influence of background noise on autocollimator measurement precision and method for uncertainty source elimination

Reflection phenomenon of internal optical structure surface of the autocollimator will cause background noise to interfere with its imaging and localization results, thus reducing the measurement precision. The non-working surface reflection of the beam splitter is the main factor causing this uncertainty source. Using a polarized beam splitter cube to replace the original beam splitter and combining with other polarization devices can effectively suppress the influence of this uncertainty source on the goniometric accuracy of the autocollimator. In this paper, through the comparison experiment with the benchmark instrument, it is found that after eliminating the noise, the measurement accuracy along the X and Y axes is improved from less than 5.26″ to better than 2.69″, the resolution is improved from 2″ to approximately 1″, and the uncertainty of the systematic measurement is improved from 5.67″ to approximately 3.43″.