Accurate determination of subnanoscale deformation with combined laser calorimetry and surface thermal lens technique

Abstract

Laser-induced surface deformations of optical components are measured with a combined laser calorimetry (LC) and surface thermal lens (STL) technique. The deformation is calculated from the STL amplitude by employing a simple STL model. It is also directly calculated with a rigorous deformation model by measuring the absorptance of the optical component with LC. Experimentally, the laser-induced surface deformation values of a BK7 coating sample measured by STL and Hartmann wavefront sensing techniques are in excellent agreement with that calculated with the rigorous deformation model. The measurement of subnanometer deformation with the combined LC and STL technique is demonstrated by a fused silica coating sample. The deformation measurement sensitivity and error are estimated to be 10 pm and below 10%, respectively.