Non-Invasive Measurements of Temperature Using Near Infrared Light

We have proposed a new method of measuring temperature of media containing water by near infrared spectroscopy and multivariate analysis. The peak wavelength of the water absorption band at about 1450 nm shifts with the change in temperature. By measuring the wavelength shift of the absorption band we can measure the temperature of media containing water whenever it is transparent like water solutions or turbid like biological tissues. Fundamental experiments have validated the proposed method. The measurement accuracy has been found to be less than 0.1 °C for pure water, 0.3 °C for turbid media with transmission measurement, and 0.6 °C for turbid media with reflection measurement.