Error analysis of back focal length measurement technique for long focus large-scaled lenses

Interference method of testing the long-focus focusing lenses allows measuring such optical parameters as focal distances and distortions of wavefront passing through the lens. High measurement accuracy is achieved by means of a special laser measurement system (laser tracker) in autocollimation schematic based on dynamic interferometer. Main sources of instrument error were found out and their relation to the measurement schematic parameters was defined. The article shows that the method allows achieving total instrument measurement error of the 0.003% of the value being measured.