Photothermal Common-Path Interferometer

The Photothermal Common-Path Interferometer is a modification of a thermal lens setup. The setup is optimized in a way that a single probe beam detects refractive index changes induced by a pump with a sensitivity of a two-beam interferometer. An absorption as low as10 ppb could be detected with a 10W laser pump.

General capabilities and recent extensions of the technology will be presented, such 3D absorption mapping, thermal diffusivity tests, non-thermal responses like photorefraction, etc.

There are two photothermal systems working in Ginzton Lab now and over twenty systems in operation worldwide. These have been manufactured and installed by Stanford Photo-Thermal Solutions, a small business where I serve as CTO.