Design and test of imaging spectrometer’s dual dispersive prisms

Dual dispersive prisms are the key dispersive component of high resolution space-borne imaging spectrometer. Their opto-mechanical mounting is an important problem which must be resolved during imaging spectrometer engineering development phase. Firstly, the working principle of dual dispersive prisms was introduced and their opto-mechanical mounting requirements were also presented. Furthermore, after taking into account coefficient of expansion matching, density, modulus of elasticity, machining property and so on, dual dispersive prisms mounting material was confirmed. Moreover, the great difference of coefficient of expansion between one of dual dispersive prisms and its mounting material was compensated using the temperature compensation method. Afterward, the dual dispersive prisms were mounted by the semikinematic mounting method. Finally, Mechanics analysis and thermoanalysis results were proposed, subsequently corresponding tests were also carried out. Tests results indicate that the nature frequency of dual dispersive prisms assembly is 301.5 Hz, integrative OPD of dual dispersive prisms assembly is better than 0.021 (=632.8 nm) at 20℃ 5℃ . The results proved the dual dispersive prisms assembly satisfied the requirements of imaging spectrometer.