Temperature dependence of light absorption in water at holmium and thulium laser wavelengths

Abstract

A simple experimental setup is described that facilitates accurate measurements of the temperature-dependent water absorption coefficient in the mid-infrared spectral region. With this setup, the absorption of holmium and thulium laser radiation in water was quantified to a precision of 0.5%. In the 20-100 degrees C temperature range, a linear decrease of the absorption coefficient with temperature is observed. The slope coefficients amount to -0.104 +/- 0.001 and -0.259 +/- 0.003 l/(K cm) for 2090-nm holmium and 2014-nm thulium radiation, respectively. At both wavelengths, this bleaching reduces the absorption coefficients of water at 100 degrees C by one third when compared with room temperature. A numerical simulation shows that the variable absorption has a noticeable influence on peak temperatures in laser heating of water.

Infrared Transmission Characteristics and Laser Tissue Interaction of Albino Pigskin Using Pulsed NIR Laser Light

“…As the sample temperature increases gradually, the moisture content continuously decreases (Figure 7). ese transmission characteristics are comparable to water, whose absorption coefficient is also inversely proportional with temperature [9]. As skin samples contain up to 80% water [10], its absorption should also decrease with temperature and the results shown demonstrate the same.…”

Fetd Computation of the Temperature Distribution Induced Into a Human Eye by a Pulsed Laser

“…Variations of the absorption coefficient in the mid-infrared region due to increased temperature has been known [42,43], and this dynamics has been recently taken into account in the simulation of the laser-induced thermotherapy [44]. Since we confirmed that this parameter plays significant role in the maximum temperatures achieved, values should be used with caution.…”

High-power laser vaporization of the canine prostate using a 110 W Thulium fiber laser at 1.91 ?m

“…First, the Thulium fiber laser wavelength is tunable between 1.75 and 2.22 mm, allowing it to match the 1.94 mm water absorption peak for more efficient tissue ablation. This water absorption peak shifts to 1.92 mm at higher ablative tissue temperatures [23,24]. The thermal damage zone in soft tissues increases from 100 mm at 1.92 mm to 400 mm at the 2.12 mm Ho:YAG laser wavelength [25].…”