Analysis on the system error cause by lateral departure of the light source during Ronchi test

Abstract

The Ronchi test is very useful for the testing of large aperture astronomical optical element, and will be more useful with the achievement of testing in a quantitative way. While when it comes to application, the light source should has a certain extent lateral departure away from the optical axis so that the image of it is apart away form itself and can be captured. This lateral departure produces the system error in the measurement. By means of optical design software, this paper studies the system error of the Ronchi test produced by the lateral departure of light source on the base of the simulation and the calculation of error according to the different distances from the optical axis, and discusses the conditions satisfied with a certain measurement requires on the foundation of the outcome. Then a system device including the light source that can be used in the practice of the measurement is designed. This device also is very useful for the other testing methods that need a high power and large relative diameter light source.