Diffraction effect and its elimination method for diamond-turned optics

In the visible light band, the diffraction effect of a diamond-turned surface will cause the optical performance to heavily deteriorate. Due to the insufficient understanding of diffraction effect, post-treatment, such as polishing technology has to be fulfilled. To reveal the origins of diffraction effect of the diamond-turned surface under visible light, theoretical analyses are carried out with consideration of the influencing factors in diamond turning. Simulation results, coupled with experimental observations, demonstrate that the periodic components of surface roughness are responsible for the diffraction light distribution in the horizontal direction of the receiving screen. However, the aperiodic components of surface roughness, derived from defects in material matrix, result in the diffraction spots on the whole receiving screen. To directly eliminate the diffraction effect in diamond turning, a novel method—with control on tool edge quality, material defects, and processing parameters—is proposed. The measurement results prove the effectiveness of this method, and the diffraction-free surface finish without any post-treatment is successfully acquired.