Optimization Design Method And Integration Technology For Prism-grating Hyperspectral Imaging Spectrometer

Imaging spectrometer is an equipment that integrating precision optical technology, precision machinery technology, weak signal detection technology, detector technology, information processing technology, etc. And it is not only the essential instrument to obtain the image and spectral information of the target, but also the fundamental research equipment in fields like aerospace remote sensing, mineral exploration, medical research, agricultural testing, military reconnaissance, etc. The beam splitting techniques adopted in imaging spectrometers directly affect their structure complexity, size, weight and capability. And it’s extremely important to select the appropriate beam splitting techniques according to the technical specifications of imaging spectrometers.Traditional imaging spectrometers based on dispersive prisms or plane gratings are faced with the problem of spectral smile and spectral keystone, making the accurate extraction of three-dimensional information more difficult. According to the view of the contrary behaviors in emergence angles and spectral smile directions when plane waves passing though prisms and plane gratings individually, a novel prism-grating dispersive element capable of removing spectral smile is proposed in this paper, and its design technique and application technique are intensively studied. The main work is as follows:First, a novel prism-grating dispersive element capable of removing spectral smile is proposed and its numerical model is built up by vector method. Based on the model, the spectral smile properties of separate prisms and gratings, and the spectral smile complementary property of two dispersive elements are further quantitatively analyzed and the structural parameters of the dispersive element are optimized.Second, based on the prism-grating dispersive element with optimized structural parameters, a prism-grating hyperspectral imaging spectrometer is designed with excellent optical capability and approximate direct vision. And the optical design and tolerance allocation method involved are presented in detail.Third, according to the optical system properties of the prism-grating hyperspectral imaging spectrometer and based on the modular idea, the corresponding alignment program is put forward and its mechanical design and precision alignment are completed. According alignment scheme, the overall alignment program is divided into six separate modules. In all module designs, the functions of their optical system are ensured and the necessary alignment structures are introduced. There are also inter-module alignment interfaces to ensure the subsequent accurate alignment. According to the alignment scheme, the overall system is divided into seven optical alignment steps. The precision alignment methods of each step have been discussed in detail. In order to ensure accurate alignment, the self-collimation method is employed to get the alignment postures of the modules in the alignment process.At last, a spectral calibration system is designed. The spectral calibration of the prism-grating hyperspectral imaging spectrometer is accomplished and its spectral response function is acquired by the spectral calibration system. Besides, both indoor testing and outdoor testing of the imaging spectrometer are carried out and the expected result is achieved. It is evident that the mechanical design, alignment program, calibration methods of the imaging spectrometer are both right and effective from the core dispersive element design to the overall optical design.