Compact high-aperture interferometer with a diffractive reference wave for high-precision referenceless aberration measurements of optical elements and systems

We present the optical layout and actual design of a compact high-aperture referenceless point diffraction interferometer with a diffraction reference wave. The basic concept of this interferometer is based on a single-mode optical fibre with a subwave output aperture, which is used as a source of spherical reference waves. The interferometer is designed for high-precision measurements of the surface shape and aberrations of optical elements. It makes use of a diffraction reference wave and is developed for mass industrial applications. The proposed design does not require the involvement of special external conditions, and reduces the need for calibrated reference surfaces. We evaluate the performance of our interferometer for highprecision measurements and demonstrate its use by presenting results obtained from measuring the shapes of spherical references from various manufacturers and the aberration of a five lens objective.