Study of zero position variation for an optical sight by using a CCD

When measuring the pure zero position variation of a high-precision optical sight, it is necessary to eliminate the error caused by repeated installation on the fixture. Traditional measurement methods require two subsystems to obtain pure zero position variation. This solution is complex, costly, and has low measurement efficiency. Therefore, this paper proposes a new method based on a CCD camera to measure the zero position variation of high-precision optical sights. The system uses a collimator, an optical sight, and a CCD camera to build a measurement platform. The coordinate system is established on the CCD imaging surface, and the repeated installation error of the sight is obtained by the variation of the image on the CCD image surface by the collimator’s reticle before and after the test. The total zero position variation of the sight is measured by the variation of the image on the CCD image surface by the sighting reticle before and after the test. Finally, the pure zero position variation is calculated by the difference between the two reticles in the CCD image plane. The method in this paper can measure the pure zero position variation of the optical sight with only one CCD camera. Testing has verified that the measurement accuracy of the system can reach 2′′, which is enough to conform to the measurement requirements of high-precision optical sights.