Accurate and wide-range radius of curvature measurement directly linked to a time standard using a Fabry-Pérot cavity

An accurate, practicable, wide-range measurement system for the radius of curvature of spherical concave mirrors using resonant mode spacing measurements of a Fabry-Pérot (FP) cavity without moving parts was developed in this study. Radius of curvature measurements for radii ranging from 500 to 5000 mm were successfully demonstrated with a repeatability of better than 3 × 10−5 using a sequential optical frequency locking procedure. The proposed measurement system was realized using a low-finesse FP cavity under ambient air conditions with few changes made to the settings for changing the target value of radius of curvature.