Accurate optical design of an acousto-optic tunable filter imaging spectrometer

When designing an acousto-optic tunable filter (AOTF) imaging spectrometer, the traditional method used a refractive grating to simulate the effects of the AOTF. We studied the acousto-optic interaction in AOTF with exact analysis and found that simulating AOTF with grating was inaccurate due to angular dependence of grating spacing. We proposed a new method to simulate the diffraction using user defined surface (UDS) function in ZEMAX based on accurate acousto-optic interaction. Optimization and analysis of the optical design for an AOTF imaging spectrometer was carried out with the UDS. The obtained geometric MTF and spectral image indicates that the proposed method is efficient, accurate and feasible for routine design of the AOTF imaging spectrometer.