Assessment of Optical Performance of Aspheric Germanium Lens Manufactured Using Single Point Diamond Turning

Abstract

Manufacturing of aspheric profile of lens at nanometric level is difficult but the measurement and evaluation of metrology parameters is still a bigger challenge. For successful results of the lens systems, precise and defect free lenses are required. The manufacturing conditions have direct effect on the metrological parameters. For appropriate evaluation of metrology parameters, proper interpretation of aspheric surface parameters must be known. . In this study, the mechanical parameters, such as radius of curvature, slope error, tilt, centre thickness, and sag value of lens, were measured by using contact type form talysurf, non-contact type fizeau interferometers, and other instruments. The experimental results reveal that an increase in the spherical aberration is caused by increasing the lens thickness beyond 4.995mm or by increasing the radius of curvature beyond −13.8396mm or by increasing the aspheric higher order coefficients. Also its dependencies on the diameter of least confusion is studied.