Research On Hyperspectral Imaging Using Dual-channel Lateral Shearing Interferometry

Hyperspectral imaging is capable of recording multidimensional information of the target in spatial and spectral domains,providing more information for improving the capability of the system of detecting and identifying the target,and has been widely used in areas such as aerospace remote sensing,biomedicine,astrophysics and national defense.The spatiotemporal mixed modulated interferometric imaging spectrometers have become the key research direction in this field due to the advantages of high throughputs,multiple channel and system stability,and combined with polarization imaging technology to form interferometric imaging spectropolarimeters.However,in the spatiotemporal mixed modulated imaging spectrometers,the limitation of the interferometric modulation structure makes the field of view(FOV)of the system narrow,and luminous flux loss of the interferometers system greatly limits the further improvement of signal-to-noise ratio(SNR).Furthermore,the polarization information is generally acquired with the tradeoff of the decrease in spectral imaging spatial resolution in spatiotemporal mixed modulated interferometric imaging spectropolarimeters.Following the development trend of wide FOV,high SNR and high spatial resolution of hyperspectral imaging,this paper studies the above issues,and the main research content includes the following parts:Aiming at the limitations of interference structures on the FOV,SNR,and spatial resolution of spatiotemporal mixed modulated interferometric hyperspectral imaging systems,a dual rectangular lateral shearing interference structure was invented to achieve dual channel lateral shearing of the beam.The shear characteristics and structure characteristics of the dual-channel lateral shearing interferometer are analyzed,and the dual-channel shear interference spectral imaging model is improved,which provides theoretical basis for the FOV expansion and SNR improvement for spatiotemporal mixed modulated imaging spectrometers,and the spatial resolution improvement for interferometric imaging spectropolarimeters.Aiming at the problem of small FOV in spatiotemporal mixed modulated interferometric hyperspectral imaging systems,the large FOV interferometric imaging spectrometer using dual-channel lateral shearing interferometer is presented,and the large FOV can be obtained by stitching the individual FOVs of different channels together.The stitched FOV can be 1.8 times as the single channel's FOV.In principle,dual FOVs spectral imaging is realized by using the presented dual-rectangle lateral shearing beam splitter.In algorithm,the fast sub-pixel registration of interferograms and image stitching algorithm are studied to realize the accurate extraction of interference information and dual-channel stitching.A dual-channel lateral shearing interferometric hyperspectral imaging experimental setup was constructed and the spectral imaging experiment was carried out.Large-FOV spectral images of a scene were acquired experimentally at visible wavelengths,confirming the effectiveness of the proposed dual-channel imaging spectrometer.Aiming at the problem that the SNR is limited by the loss of luminous flux in spatiotemporal mixed modulated interferometric hyperspectral imaging systems,the dual-channel lateral shearing interferometric high SNR spectral imaging method is proposed.The luminous flux loss can be avoided in dual-channel system due to the advantage of no backtrack light,making the SNR of the proposed system(?)times as that of the single channel system.In principle,two channels of the system are used to image the same field of view of the target to improve the energy utilization of the target light.In algorithm,the high SNR interference information of the dual-channel system can be extracted by differential extraction method,thereby improving the spectral SNR of the system.SNR of the proposed system is(?)times as that of the single channel system under the same conditions of electronic device parameters and interference sampling conditions.The spectral SNR of dual-channel differential interferometric hyperspectral imaging method is simulated,and an experimental setup was constructed to carry out experiments to obtain high SNR spectral reconstruction information.Compared with the single-channel detection system,the spectral SNR of the presented differential interferometric hyperspectral imaging system is(?)times as that of the single-channel system.Aiming at the problem of spectral image resolution reduction in spatiotemporal mixed modulated interferometric imaging spectropolarimeters,an imaging spectropolarimeter using dual-channel lateral shearing interferometer is proposed.The composite imaging is performed by a dual-channel shearing interference imaging system,and two channels of the system are respectively used for spectropolarimetric imaging and high spatial resolution spectral imaging.The spatial resolution of images from the spectral imaging channel will be 4 times as that from the spectropolarimetric imaging channel if the two channels have the same pixel size.Spectropolarimetric imaging based on micro-polarization array modularization is proposed for the spectropolarimetric imaging channel,and spectropolarimetric imaging is realized by using spatiotemporal mixed modulation for spectral modulation and split focal plane method for polarization modulation.Polarization modulation is not applied in the other channel,avoiding the resolution reduction of spectral image.A dual-channel lateral shearing interferometric spectropolarimetric imaging experimental setup was constructed and the spectropolarimetric imaging experiment was carried out.High spatial resolution spectral images and polarization images of a scene were acquired by the experimental apparatus.