We report a technique for rapidly mapping absorbing defects in optical materials, which act as laser-induced damage precursors, based on full-field photothermal reflectance microscopy. An intensity-modulated pump beam heats absorbing defects in the optical sample, creating localized, modulated refractive-index variations around the defects. A probe beam then illuminates the defect sites, and the measured amplitude of the reflectance variation is used to map the distribution of defects in the medium. Measurements show that this method offers a faster defect mapping speed of about 0.03 mm2 per minute and a detectivity of a few tens of nanometers comparable to that of conventional scanning photothermal deflection microscopy.
© 2013 Optical Society of America
Original Manuscript: September 3, 2013
Revised Manuscript: October 21, 2013
Manuscript Accepted: October 23, 2013
Published: November 15, 2013
Woo June Choi, Seon Young Ryu, Jun Ki Kim, Jae Young Kim, Dong Uk Kim, and Ki Soo Chang, "Fast mapping of absorbing defects in optical materials by full-field photothermal reflectance microscopy," Opt. Lett. 38, 4907-4910 (2013)