Simulation of pressure induced length change of an optical cavity used for optical pressure standard

Abstract

The National Institute of Metrology (NIM) has constructed a dual optical cavity for the optical pressure standard project. The elastic deformation induced by pressure is investigated by finite element analysis (FEA) simulation. The distortion coefficient, fractional length change per unit pressure, is calculated to be (9.936 ± 0.014)×10−12/Pa for the measurement channel and (1.49 ∼ 1.54)×10−11/Pa for the reference channel. The gravity-induced deformation is also modelled to evaluate the sensitivity to the low-frequency vibration. The cavity is modelled to be supported symmetrically on four points. With optimized support position, the sensitivity to vertical acceleration reduces to 19 kHz/(m/s2) at 633 nm.