High resolution determination of radii of curvature using Fabry–Perot interferometry

Abstract

A spectroscopic approach to measuring the radius of curvature of a concave mirror is presented. The mirror is incorporated into a plano-concave Fabry–Perot cavity and the radius of curvature of the concave mirror is inferred from the mode spacing of the transverse modes relative to the longitudinal modes. No mechanical displacement is entailed and the measurement is easily performed in vacuum. The spectroscopic resolution of the technique is better than 1 µm for a nominal radius of curvature of 1 m, but the accuracy is limited by the figure of the plane mirror in the cavity to approximately 1 mm in the present work. The optical spot size on the mirror under test is of the order of 0.3 mm, so the method should allow the radius of curvature of a mirror to be mapped out spatially with very high resolution.

Accurate Gouy phase measurement in an astigmatic optical cavity

“…The best approach to gain access to the Gouy phase is to make use of higher-order transverse modes of the cavity. This idea has been used to measure the radius of curvature of the curved mirror of a plano-concave cavity [21] with high precision; here, we interpret similar experiments in terms of the Gouy phase shift. Expanding the reflective phase shift uðmÞ to first order as…”

Laser Lens Size Measurement Using Swept-Source Optical Coherence Tomography

“…Lawall et al incorporated concave mirror into plano-concave Fabry-Perot cavity to measure ROC by using the principle of multi-beam interference [4]. Sun et al demonstrated a differential radius-measuring system to perform high-precision ROC measurement through the interference-length measuring technology [5]. Wang et al proposed a differential confocal self-collimation decentration measurement method, which can obtain ROC of optical element by using the differential confocal to precisely identify the center and vertex positions of the tested lens surface [6].…”