High-precision method for measuring the photothermal properties of transparent media with digital holography

Quantitative phase microscopy by digital holography provides direct access to the phase profile of a transparent subject with high precision. This is useful for observing phenomena that modulate phase, but are otherwise difficult or impossible to detect. In this letter, a carefully constructed digital holographic apparatus is used to measure optically induced thermal lensing with an optical path difference precision of less than 1 nm. Furthermore, by taking advantage of the radial symmetry of a thermal lens, such data are processed to determine the absorption coefficient of transparent media with precisions as low as 1×10−5 cm−1 using low power (30 mW) continuous wave (CW) excitation. OCIS codes: 090.0090, 090.1995, 350.6830. doi: 10.3788/COL201109.120001.