High-Precision Measurement of Dielectric Microsphere Diameter Using Whispering Gallery Mode Resonance

Abstract

The accuracy of Micro-CMMs for three-dimensional shape measurement is influenced by the size and the shape of the probe sphere, whose diameter is often only about 50-100 μm. In order to measure the diameter of those microspheres precisely, a new method based on the analysis of an optical phenomenon called whispering gallery modes (WGMs) is proposed. In this paper, a high precision WGM resonance wavelength measurement of a standard deviation of 1 pm is achieved. Applying it to measure a microsphere whose diameter was about 55 μm, the measurement result showed that the precision of the proposed method was 3.1 nm.