Research on Kinematic Error of Pendulum Interferometer Based on Optomechanical Coupled Simulation

To address the issue of normal displacement deviation induced by the geometric nonlinearity of cross-spring flexural pivots in pendulum-type interferometers, which leads to modulation attenuation, this study proposes a co-simulation method combining Finite Element Analysis (FEA) and Physical Optics. First, an optomechanical model was established based on the retroreflective property of cube-corner prisms and a double-pendulum differential scanning architecture (where the optical path difference is four times the mechanical displacement). Using the ANSYS Workbench 2022 R1 transient dynamics module with the “Large Deflection” algorithm enabled, the nonlinear motion trajectories of single-pivot and dual-pivot flexural hinges were quantitatively compared. Subsequently, a multi-physics data mapping interface was established to map mechanical motion errors into a physical optics simulation model, where the interference modulation was accurately calculated via electromagnetic field tracing. Results demonstrate that under ambient temperature (25 °C) and a spectral resolution of 1 cm−1, the normal displacement deviation of the single-pivot hinge is only 0.00165 mm, representing a 95.6% reduction compared to the dual-pivot structure (0.03765 mm). Furthermore, the modulation of the single-pivot structure remains above 0.98 throughout the scanning range, significantly outperforming the nonlinear decay characteristic of the dual-pivot structure. These findings provide a theoretical basis for the structural optimization and selection of high-precision portable FTIR spectrometers.