A collinear photothermal detection bench is described that makes use of a position-modulated heating source instead of the classic power-modulated source. This new modulation scheme increases by almost a factor 2 the sensitivity of a standard mirage bench. This bench is then used to measure the absorption coefficient of OH-free synthetic fused silica at 1064 nm in the parts per 10<sup>6</sup> range, which, combined with spectrophotometric measurements, confirms that the dominant absorption source is the OH content.
© 2003 Optical Society of America
Vincent Loriette and Claude Boccara, "Absorption of Low-Loss Optical Materials Measured at 1064 nm by a Position-Modulated Collinear Photothermal Detection Technique," Appl. Opt. 42, 649-656 (2003)