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1. Visible-Light-Induced Dearomatizations: Visible-Light-Induced Dearomatizations

   https://doi.org/10.1002/ejoc.201901229  

   Okumura, Mikiko; Sarlah, David (October 2019, European Journal of Organic Chemistry)
2. “Invisible” Digital Light Processing 3D Printing with Near Infrared Light

   https://doi.org/10.1021/acsami.1c22046  

   Stevens, Lynn M.; Tagnon, Clotilde; Page, Zachariah A. (May 2022, ACS Applied Materials & Interfaces)
3. Endoscopic hyperspectral imaging: light guide optimization for spectral light source

   https://doi.org/10.1117/12.2290615  

   Browning, Craig M.; Mayes, Sam; Rich, Thomas C.; Leavesley, Silas J. (February 2018, Proc. SPIE 10487, Multimodal Biomedical Imaging XIII, 104870H)

   Hyperspectral imaging (HSI) is a technology used in remote sensing, food processing and documentation recovery. Recently, this approach has been applied in the medical field to spectrally interrogate regions of interest within respective substrates. In spectral imaging, a two (spatial) dimensional image is collected, at many different (spectral) wavelengths, to sample spectral signatures from different regions and/or components within a sample. Here, we report on the use of hyperspectral imaging for endoscopic applications. Colorectal cancer is the 3rd leading cancer for incidences and deaths in the US. One factor of severity is the miss rate of precancerous/flat lesions (~65% accuracy). Integrating HSI into colonoscopy procedures could minimize misdiagnosis and unnecessary resections. We have previously reported a working prototype light source with 16 high-powered light emitting diodes (LEDs) capable of high speed cycling and imaging. In recent testing, we have found our current prototype is limited by transmission loss (~99%) through the multi-furcated solid light guide (lightpipe) and the desired framerate (20-30 fps) could not be achieved. Here, we report on a series of experimental and modeling studies to better optimize the lightpipe and the spectral endoscopy system as a whole. The lightpipe was experimentally evaluated using an integrating sphere and spectrometer (Ocean Optics). Modeling the lightpipe was performed using Monte Carlo optical ray tracing in TracePro (Lambda Research Corp.). Results of these optimization studies will aid in manufacturing a revised prototype with the newly designed light guide and increased sensitivity. Once the desired optical output (5-10 mW) is achieved then the HIS endoscope system will be able to be implemented without adding onto the procedure time. 

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4. Coherent light filter

   https://doi.org/10.1364/OL.447393  

   Bergthold, Morgan; Stewart_Jr, Keith; Duggar, Nicholas; Muhowski, Aaron_J; Wasserman, Daniel (May 2022, Optics Letters)

   We demonstrate efficient filtering of coherent light from a broad spectral background. A Michelson interferometer is used to effectively filter out the coherent emission of mid-infrared lasers from the co-propagating incoherent emission of a broadband thermal source. We show coherent light suppression as high as 16.9 dB without any modification of the broadband incoherent background spectrum. In addition, we demonstrate the ability to measure the spatially dependent (incoherent) thermal emission from a patterned surface, using our filter to remove a coherent signal which would otherwise overload our detection system. The demonstrated filter is rapidly tunable and wavelength-flexible, and has potential for imaging and spectroscopy applications in the presence of an otherwise overpowering coherent signal. 

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5. Kaleidoscopic structured light

   https://doi.org/10.1145/3478513.3480524  

   Ahn, Byeongjoo; Gkioulekas, Ioannis; Sankaranarayanan, Aswin_C (December 2021, ACM Transactions on Graphics)

   Full surround 3D imaging for shape acquisition is essential for generating digital replicas of real-world objects. Surrounding an object we seek to scan with a kaleidoscope, that is, a configuration of multiple planar mirrors, produces an image of the object that encodes information from a combinatorially large number of virtual viewpoints. This information is practically useful for the full surround 3D reconstruction of the object, but cannot be used directly, as we do not know what virtual viewpoint each image pixel corresponds---the pixel label. We introduce a structured light system that combines a projector and a camera with a kaleidoscope. We then prove that we can accurately determine the labels of projector and camera pixels, for arbitrary kaleidoscope configurations, using the projector-camera epipolar geometry. We use this result to show that our system can serve as a multi-view structured light system with hundreds of virtual projectors and cameras. This makes our system capable of scanning complex shapes precisely and with full coverage. We demonstrate the advantages of the kaleidoscopic structured light system by scanning objects that exhibit a large range of shapes and reflectances. 

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