Study On The Computed-tomography Imaging Spectrometry

This dissertation presents theoretical and experimental studies of computed- tomography imaging spectrometry (CTJS) in details, which includes the following main parts: 1. The imaging spectrometry and its application The development, principles, classification and application of imaging spectrometry are introduced. The concept of 揹ata cube?is analyzed and developed. Then, the methods in which 揹ata cube?is acquired by all the different spectral imagers are presented in details. The dispersive and interfering imaging spectrometer can obtain only a slice or a curve of 揹ata cube?in each exposure. However, the CTIS can obtain one or more projection(s) of 揹ata cube?in each exposure. 2. The principles of computed-tomography (CT) The principles of CT are firstly introduced. Then we proved the theory of Radon transform and the central slice theorem by simulated experiements. By applying the CT to imaging spectrometry, the CTIS is developed. 3. The non-scanning computed-tomography imaging spectrometer Employing a 2-D grating, the non-scanning spectral imager can acquire several projections of 揹ata cube?in each exposure. According to the principles of CT, we can reconstruct the data cube using these projections. The reliability and stability of the CTIS 憇 projector matrix depend on its 2-D condition number. Directed by this rule, we can optimize the diffraction efficiency of the 2-D grating. By many simulated experiments we discover a important conclusion that the matrix抯 condition number minimizes when all the projections?intensity equals. Considering the 2-D condition number rule, central slice theorem, requirement on computer, resolution, grating?fabrication, we choose the 1-order diffraction mode of the grating. The correlative CT algorithms are presented and improved. We tested these algorithms by simulated experiments, and finally chose the expectation III I? maximization algorithm. We developed and calibrated a CTIS. The resulting spectral image consists of 95 *95 spectral pixels and 32 spectral bands, and the synthesized color image is close to the origin object. 4. The high-throughput chromotomographic imager (HTCTI) The high-throughput chromotomographic imager can acquire a projection of 揹ata cube?in each exposure. If the direct view prism is rotated around the optical axis, and the projections along different directions can be obtained. The 揹ata cube? can be reconstructed from these projections by CT algorithm. In order to fill the missing cone caused by the limited-angle chromotomographic images, we designed the ordered subset expectation maximization algorithm (OSEM). The simulated experiments show that OSEM algorithm is more convergent, more reliable, and more efficient in filling the missing cone than other previous algorithms in frequency domain. We have developed and calibrated a HTCTI, and the resulting spectral image consists of 245*245 spectral pixels and 32 bands. 5. Computed-tomographic pushbroont imaging spectrometry A new pushbroom chromotomographie imager with a linear CCD is produced in this paper. It employs a linear CCD other than an area CCD employed by other...