Browsing by Author "Zheng, Desheng"

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    Radiometric and design model for the tunable light-guide image processing snapshot spectrometer (TuLIPSS)
    (Optical Society of America, 2021) Zheng, Desheng; Flynn, Christopher; Stoian, Razvan I.; Lu, Jiawei; Cao, Haimu; Alexander, David; Tkaczyk, Tomasz S.; Bioengineering; Electrical and Computer Engineering; Physics and Astronomy
    The tunable light-guide image processing snapshot spectrometer (TuLIPSS) is a novel remote sensing instrument that can capture a spectral image cube in a single snapshot. The optical modelling application for the absolute signal intensity on a single pixel of the sensor in TuLIPSS has been developed through a numerical simulation of the integral performance of each optical element in the The tunable light-guide image processing snapshot spectrometer (TuLIPSS) is a novel remote sensing instrument that can capture a spectral image cube in a single snapshot. The optical modelling application for the absolute signal intensity on a single pixel of the sensor in TuLIPSS has been developed through a numerical simulation of the integral performance of each optical element in the TuLIPSS system. The absolute spectral intensity of TuLIPSS can be determined either from the absolute irradiance of the observed surface or from the tabulated spectral reflectance of various land covers and by the application of a global irradiance approach. The model is validated through direct comparison of the simulated results with observations. Based on tabulated spectral reflectance, the deviation between the simulated results and the measured observations is less than 5% of the spectral light flux across most of the detection bandwidth for a Lambertian-like surface such as concrete. Additionally, the deviation between the simulated results and the measured observations using global irradiance information is less than 10% of the spectral light flux across most of the detection bandwidth for all surfaces tested. This optical modelling application of TuLIPSS can be used to assist the optimal design of the instrument and explore potential applications. The influence of the optical components on the light throughput is discussed with the optimal design being a compromise among the light throughput, spectral resolution, and cube size required by the specific application under consideration. The TuLIPSS modelling predicts that, for the current optimal low-cost configuration, the signal to noise ratio can exceed 10 at 10 ms exposure time, even for land covers with weak reflectance such as asphalt and water. Overall, this paper describes the process by which the optimal design is achieved for particular applications and directly connects the parameters of the optical components to the TuLIPSS performance.
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    Visible and short-wave infrared fiber-based snapshot imaging spectrometer with a custom high-throughput relay system
    (Optica Publishing Group, 2023) Lu, Jiawei; Zheng, Desheng; Stoian, Razvan-Ionut; Flynn, Christopher; Alexander, David; Tkaczyk, Tomasz S.; Bioengineering; Electrical and Computer Engineering; Physics and Astronomy
    This paper presents the design and fabrication of a fiber-based snapshot imaging spectrometer working in both visible (490 nm-732 nm) and short-wave infrared (1090 nm - 1310 nm) ranges. To maximize the light collection efficiency, a custom relay system with 0.25 NA and 20 mm field of view (FOV) was designed and integrated. The bench setup showed that the custom relay system could fully resolve 10 µm fiber cores over the entire FOV among visible and short-wave infrared ranges. The numerical aperture (NA) match provided a 2.07X fold throughout improvement in the visible range and about 10X fold in the SWIR range compared to the previous generations, enabling imaging with a fast frame rate and under low illumination conditions. The presented imaging spectrometer generated spectral datacubes with 35000 spatial samplings and 23 spectral channels. Spectral urban imaging results obtained by the spectrometer in both visible and SWIR ranges are presented. Finally, we collected spectral images of apple bruising to show potential applications in the food quality industry.