Assessment of the impact of autocollimator operating conditions on the accuracy of angular measurements

Autocollimator is a common device for non-contact measurement of the angular position of objects in space. Its accuracy can vary from a few arc seconds to a hundredth of an arc second, and the more accurate the device, the more factors must be taken into account during measurements. At the moment, there is already a significant body of research on the factors that affect angular measurements using an autocollimator. These include the size, reflectivity, and flatness of the reflecting surface; the distance between the surface and the autocollimator; the presence and configuration of any aperture in the beam path of the autocollimator; and many other factors. Typically, the object of these studies is a high-precision autocollimator (with accuracy greater than 0.1 arc seconds), and the contribution of studied parameters is usually less than 1-2 tenths of an arc second. <br/><br/> In the process of using a less accurate digital autocollimator (with a claimed accuracy of 0.25 arc seconds), the authors also encountered the influence of various parameters in the measurement setup, but of a greater value. This led to additional research. <br/><br/> This paper presents an experimental analysis of the complex effects of the distance to the reflecting surface and its size, as well as the impact of non-flatness on the surface. The random errors of the autocollimator in different operating modes are also analyzed.