Interferometric Method to Control the Convex Aspherical Surface Shape using a Concentric Meniscus Lens

Abstract

Convex aspherical surfaces are being increasingly used as elements of the high-precision optical devices for various purposes. Complexity in such surfaces manufacture is because the existing methods of their shape control with the optical accuracy of about 20--30 nm require introduction of the auxiliary reference optical elements, which dimensions are several times larger than those of the controlled part are. The paper proposes the autocollimation control method using a concentric meniscus lens with dimensions slightly exceeding the dimensions of the controlled part. Results of calculating the control circuit design parameters are presented based on the theory of the third-order aberrations. Effect of the refractive index and thickness of a concentric meniscus lens on the maximum and root-mean-square deviations of the surface shape with various requirements to concentric meniscus lens radii was considered, and the developed scheme simulation in the Zemax soft-ware was also proposed. The Fizeau interferometer optical scheme was described using a lens with the reference surface to implement the developed method. Applied research was carried out to control the secondary mirrors of the Ritchie --- Chretien telescope at the Hoa Lak Observatory (Vietnam) and of the SNAP satellite telescope