10 April 1995 High-sensitive transformer of infrared images into visible range
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The theory of new imaging processes is proposed based on quenching or gain effects of visible secondary radiation in perfect crystals (e.g. CdS by incident mid IR or far IR radiation). Three types of the transformation processes from IR into visible range are considered both theoretically and experimentally. The first is based on IR-quenching effect for Raman light scattering (RLS) due to collisions of free and bound Wannier-Mott excitons at helium temperatures. To use this effect for imager design it must have some advantages compared with the usual thermovision systems: (1) highest sensitivity, (2) great protection against background IR radiation, (3) the possibility to design far IR TV photocathodes, (4) highest spatial resolution, that is near the same as one restricted by the number of fibers in line served for the transferring of visible image from the crystal immersed in liquid helium to the CCD array beyond the cryostat; (5) low heating of liquid He (power of UV excitation of the crystal is less than 10 mW). The second one is based on IR-quenching effect for probe visible radiation in the crystal relative transparency region at room temperature with participation of spherical excitons. The third one is based on the stimulated gain due to two-photon emission connected with interactions of Wannier-Mott excitons with spherical excitons. In the process the gain effect must be observed for both submillimeter waves with large angular momenta and visible radiation at the frequency of resonant direct transition from A(n equals 1) and B(n equals 1) states of Wannier-Mott excitons.
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Gennadii K. Vlasov, Gennadii K. Vlasov, } "High-sensitive transformer of infrared images into visible range", Proc. SPIE 2415, Charge-Coupled Devices and Solid State Optical Sensors V, (10 April 1995); doi: 10.1117/12.206528; https://doi.org/10.1117/12.206528

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