Aspheric Off-axis Type Cgh-based Detection Technology Research

The aspherics can improve the performance of optical systems effectively, the surface test technology that is high-accuracy and large amount of data, is an important study to promote the wide use of aspherics.On the basis of relevant research, the technique of the Twyman-Green interferometer with off-axis CGH test aspheric surfaces is discussed. the experimental system is designed by the optical design software Zemax, the collimator of the system and diverger lens which is used to compensate aspherics surface error are designed, and then a in-line CGH is joined in the system, phase of the wave front after the aspheric wave front under test passing diverger lens will be obtained. The volume of the carrier frequency of off-axis CGH is calculated theoretically, then the deflection angle 1.71°of reference light is obtained. Based on the above results, the phase distribution function of the off-axis CGH is gained by Zemax. And further the influence of the location deviation of CGH to the entire system is discussed, it shows that the error introduced by the CGH tilting around the x-axis and y-axis as well as moving along the x-axis and y-axis direction is large. Finally, the off-axis CGH produced is placed in the Twyman-Green interferometer, and the aspherical mirror under test with 78mm in diameter was measured by this system, the testing result shows that the surface error is 0.643λP-V, then the aspheric surface is tested on the contrast in the Fizeau-type optical setup, the measurement accuracy is enough to the system.