MEASUREMENT ERROR OF A PHOTOELECTRIC AUTOCOLLIMATOR AT DIFFERENT DISTANCES TO THE AUTOCOLLIMATION MIRROR

When the plane of the mark (the reticle) does not coincide with the focal plane of an autocollimator objective, a component of the measurement error appears that depends upon the distance to the autocollimation mirror. A formula has been derived and analyzed that characterizes this error. A recommendation is given relating to the setting of the plane in which the image position of the autocollimation mark must be measured to attain the lowest error for different distances to the mirror. Experimental data for the adjustment of a photoelectric autocollimator confirm that the theoretical considerations are correct.