Imaging Analysis of a Visible-NIR Hyperspectral Imaging System and Its Optimization of Imaging Plane Positioning

• Main Authors: Cheng-Huan Wu, 吳承桓
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/08211722402594643874

碩士 === 國立臺灣科技大學 === 自動化及控制研究所 === 104 === Design of an Offner system spectrometer used for 400 – 1000 nm wavebands is introduced in this paper. It refers the divergence angle of the light, spectral imaging size, radius of concave mirror, grating pitch and the diffraction orders. X coordinates presents the slit image direction, Y is the spectral resolution direction and Z is the light propagation direction. Point and slit light source are used for the performance analysis. In this paper, the point light source uses a detector of 512 × 512 pixel number and 3.9 μm × 3.9 μm pixel size. The slit light source uses two detectors of 155 × 155 and 310 × 310 pixel number, and 12.9 μm × 12.9 μm and 6.45 μm × 6.45 μm pixel size with a slit put in front of light source. The size of slit is 0.6 mm in X and 20 μm in Y and the size of the light source is 20 μm x 20 μm in both. Five wavelengths, which are 400 nm, 550 nm, 700 nm, 850 nm, and 1000 nm specitied to analyze the quality of image. The results show that most of positions where detectors receive lights are located in the depth of focus. For a better ability of focus quality, correction for imaging plane positioning of detectors are involved. After correction, the imaging location are not only within the depth of focus, but are also approaching the minimum spot size. In point source, the FWHM spot size is smaller than 10 μm, and the total spectral resolution of the system is better than 1.02 nm. In slit source, the FWHM spot size is smaller than 24 μm, and the total spectral resolution of the system is better than 2.36 nm. In this paper, 0.3 MTF corresponds a basis of the performance for spatial frequency and pitch check image quality. In point source, MTF of 0.3 corresponds to a spatial frequency of 125 cycle/mm and a grating pitch of 8 μm. In slit source, MTF of 0.3 corresponds to a spatial frequency of 50 cycle/mm and a grating pitch of 20 μm.