Abstract：The variation of probe-tissue contact pressure will lead to poor measurement accuracy and stability in the near-infrared noninvasive diffuse reflection measurement. In this paper, the pressure-insensitive radial position was proposed to collect the diffuse reflection signal to minimize the measurement error caused by contact pressure, and the existence of pressure-insensitive radial position was verified by Monte Carlo simulation and in vivo experiment. First, Combined with human skin structure model and mechanical properties, the quantitative relationship between contact pressure and skin tissue parameters were established, and the distribution change of diffuse light intensity along radial distance within the wavelength of 1 000～1 320 nm under different contact pressure was simulated by the Monte Carlo program. Then the diffuse reflection detection system configured with the super-luminescence diodes and customized optical fibers were built, where multiple detector fibers surrounded the source fiber. And in vivo experiments were performed where the diffuse reflection signals in the wavelength of 1 050, 1 219 and 1 314 nm of three volunteers were collected under different pressure. Last, the stability of signal received from pressure-insensitive radial position and other radial position was evaluated. Simulation results showed that, the diffuse reflection signals received within the radial distance from 1.3 to 1.5 mm were not changed with the contact pressure, which means there were the pressure-insensitive radial positions. The experiment results of in vivo showed that, the pressure-insensitive radial positions could be found in all the volunteers, and they were located within the radial distance of 0.78～1.0 mm for the all wavelengths investigated. Compared with other radial positions, the signal-to-noise ratio of the signal collected under the pressure-insensitive radial position was higher. Therefore, the measurement method based on the pressure-insensitive radial position can effectively reduce the influence of the contact-pressure variation on the spectral information, and it is expected to improve the accuracy of the near-infrared noninvasive diffuse reflection measurement.
王志懋，刘 蓉，徐可欣. 漫反射接触测量中压力不敏感径向检测位置存在性研究[J]. 光谱学与光谱分析, 2018, 38(08): 2477-2482.
WANG Zhi-mao, LIU Rong, XU Ke-xin. Existence of Pressure-Insensitive Radial Position in Diffuse Reflection Contact Measurement. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2018, 38(08): 2477-2482.
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