Structural design and cryogenic stability analysis for long-wave infrared spatial heterodyne spectrometers

Under cryogenic conditions, long-wave infrared spatial heterodyne spectrometers (LWIR-SHSs) may exhibit variations in the inclination, frequency, and distortion of their interference fringes, which can affect the system’s performance. To address the stability issues associated with cryogenics, an analysis and simulation of the optomechanical system’s performance were conducted under such conditions. Employing a structural thermal optical performance (STOP) analysis, an integrated micro-stress dynamic flexible support structure for the LWIR-SHS was designed. The optimized system ensured stable operation under cryogenic conditions, maintaining the relative positional deviation of the key components below 0.00146 mm, the relative angular deviation within 25.984 ′′ , and the inclination of interference fringes in both simulation and tests less than 21°. Furthermore, in comparison to the initial system, the interference fringe distortion also decreased significantly. Cryogenic testing of the entire system validated the optimized structure’s effectiveness in minimizing variations of the interferogram, aligning with simulation predictions. This outcome demonstrates the optimization strategy’s substantial impact on enhancing both the structural stability and operational performance of the cryogenic infrared optical system.