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Diode Laser Spectroscopy for Creating Effective Measuring Systems and Their Use in Biological and Medical Research
摘要： In this paper, we present the most important principles of diode laser spectroscopy, which allow one to create fundamentally new measuring systems for diverse applications in biology and medicine. Using the diode laser spectroscopy method and its primary hardware implementation the emission of gas molecules from skin of the hand was registered and ammonia skin emission was found to be dominant. The properties of exhaled air from patients in different states were determined with another special measuring complex of diode laser spectroscopy. It was shown that when the functional state of the body changes, the gas composition of molecular substances that are present in the exhaled air is altered indirectly and their levels vary significantly depending on the health of the individual. Our findings suggest that it is possible to study the specific functional properties of the human body to facilitate assessment of the health of an individual to determine whether pathological processes occur in the body at various stages of their severity using diode laser spectroscopy. This paper presents clinical and experimental data on this issue.
关键词： non-invasive diagnostics,diode lasers,gas biomarkers,diode laser spectroscopy
更新于2025-09-23 15:19:57
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Thermometry in a Gas Discharge Cell of an Optical Wavelength Calibrator
摘要： Temperature and pressure in a sealed Ar cell of an optical wavelength calibrator are measured using diode laser spectroscopy. The values of the thermodynamic parameters allowed determination of the fluctuations of the shift of the argon line at 811.5 nm. The expected fluctuation amplitude appears lower than ±15 MHz. The result obtained indicates the applicability of the studied calibrator as an optical reference and the correctness of previous measurements of pressure shift coefficients of the 811.5 nm argon line.
关键词： thermometry,diode-laser spectroscopy,optical calibrator,low pressure RF discharge,spectral line pressure shift,argon
更新于2025-09-19 17:15:36
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CH <sub/>4</sub> Concentration Distribution in a Semiconductor Process Chamber Measured by the CT-TDLAS
摘要： We measured methane (CH4) concentration distribution in a semiconductor process chamber by using the computed tomography-tunable diode laser spectroscopy (CT-TDLAS). We designed the CT-TDLAS measurement system with a 32-laser-path. The CH4 concentration distribution was measured by the CT-TDLAS based on the 32 absorption spectra which were collected by scanning the laser wavelength around the CH4 absorption peak of 1653.7 nm. We checked linearity of the measurement, validity of the algorithm, and resolution of the computed tomography (CT) reconstructed distribution. In the algorithm check, we measured a simple concentration distribution generated in a ?ve-fold concentric cylinder. Next, we designed a semiconductor process chamber in which the 32-laser-path was installed. After quantitative evaluations of the CT reconstructed distributions by comparing the simulated results of computational ?uid dynamics, we actually measured the CH4 concentration distribution in the chamber when we streamed 10% CH4 from one of four inlet ports and nitrogen from other three ports into the chamber. The measured distributions were obviously different in accordance with the CH4 inlet location, although all the inlet ports were located cyclic-symmetrically. Those results indicated that the ?ow impedances of the four exhaust holes on the susceptor were different depending their locations.
关键词： computed tomography,semiconductor process chamber,CT-TDLAS,methane concentration distribution,tunable diode laser spectroscopy
更新于2025-09-11 14:15:04