The shift–rotation absolute testing method based on autocollimation

The shift–rotation method is an absolute testing method that has attracted much attention in recent years, and detection accuracy at the subnanometer level has been achieved. However, for flat absolute calibration, the power aberration cannot be calibrated via the traditional shift–rotation absolute testing method. To solve this problem, we propose a shift–rotation absolute testing method based on autocollimation, which detects the tilt error of the tested mirror caused by the external environment and guides the adjustment of the stage to remove it. Simulations and experiments are conducted to prove this theory. A comparison with liquid experiments shows that the autocollimated shift–rotation method can achieve accurate absolute power aberration and can compensate for the shortcomings of the traditional shift–rotation method.