Laser Induced Damage Threshold (LIDT) Monitoring

On & off-line surface measurement during LIDT testing

SID4 wavefront sensors can be applied to laser damage detection and analysis of laser-induced modification of coated or uncoated optical materials. The Phasics measurement technique allows highlighting modifications in the material, such as refractive index variations, birefringence effects related to stress or thickness differences, and surfaces modifications. SID4 quantitative phase imaging cameras are suitable for both measurement in transmission and in reflection. Single-shot pump probe measurement is of high interest in the understanding of the dynamics of physical procesess or the effects on the surface of the coatings.

• ▽ Implementation on any optical microscope

  

  The Phasics SID4 quantitative phase imaging camera is coupled to a classical bright field microscope.  A reference measurement is acquired before irradiation and the evolution of the optical path difference (OPD) is monitored during irradiation of the sample.                                                                                                                 

• ▽ Inline measurement configuration in reflection

  

  In this illustration, the changes of optical path difference are sampled using a measurement setup in reflection.

• ▽ Inline measurement configuration in transmission

  

  In this illustration, the changes of optical path difference are sampled using a measurement setup in transmission.

• ▽ SID4 - DIC - Optical surface profiler measurement comparison

  

  Surface topography maps are obtained with the in-line SID4 wavefront sensor (left column) and the optical surface profiler (middle column) on laser-irradiated sites on a silica sample. Each line corresponds to the same sites observed at different irradiation laser fluences.

  Test conditions: Laser-created Craters on Fused Silica at 1030 nm, incident angle of 45° – scale bar: 10µm – [Courtesy of L. Gallais et Douti.-Fresnel Institute].