Quantitative phase imaging applied to laser damage detection and analysis

Abstract

We investigate phase imaging as a measurement method for laser damage detection and analysis of laser-induced modification of optical materials. Experiments have been conducted with a wavefront sensor based on lateral shearing interferometry associated with a high-magnification optical microscope. The system has been used for the in-line observation of optical thin films and bulk samples, laser irradiated in two different conditions: 500 fs pulses at 343 and 1030 nm, and millisecond to second irradiation with a CO2 laser at 10.6 μm. We investigate the measurement of the laser-induced damage threshold of optical material by detection and phase changes and show that the technique realizes high sensitivity with different optical path measurements lower than 1 nm. Additionally, the quantitative information on the refractive index or surface modification of the samples under test that is provided by the system has been compared to classical metrology instruments used for laser damage or laser ablation characterization (an atomic force microscope, a differential interference contrast microscope, and an optical surface profiler). An accurate in-line measurement of the morphology of laser-ablated sites, from few nanometers to hundred microns in depth, is shown.

Wavefront Microscopy Using Quadriwave Lateral Shearing Interferometry: From Bioimaging to Nanophotonics

“…This roughness usually appears as a limitation to observe tenuous objects, but local defects of the planar interface of the substrate can also be the feature of interest for some applications. For instance, in a series of four articles, − the group of Gallais used CGM to characterize microscale damage made by high-energy, focused laser pulses on the surface of optical components. Of particular interest of this series of articles is the use of CGM in a pump–probe, stroboscopic approach to perform time-resolved OPD imaging at the picosecond time scale .…”

Analysis of laser energy deposition leading to damage and ablation of HfO2 and Nb2O5 single layers submitted to 500 fs pulses at 1030 and 343 nm

“…These sites were then characterized with scanning electron microscope (Hitachi TM-1000) and optical profilometry (Zygo Newview 7300) in order to obtain qualitative and quantitative data. Cross-checked measurements were also done on few sites per sample with atomic-force microscopy (Brucker, Dimension-Edge) and phase microscopy [21] in order to validate the depth measurements.…”

On-line detection method based on optimal modified lateral shearing interferometry for evaluating the damage growth characteristics

“…At the present time, some high-precision and high-resolution techniques, such as atomic force microscope, optical surface profiler, scanning electron microscope, are applied to detect vertical and horizontal cross sections of damage sites for estimating the damage growth behavior. [6][7][8][9][10] Thus, the lateral size and the depth of damage sites are measured accurately. However, these techniques have limitations to be inserted into the laser damage experimental setup and detect on-line the lateral size and depth of damage sites because of complex configurations.…”

“…Optical microscope recommended by ISO standard (International Organization for Standardization) is the most common technique to detect the laser-induced damage occurrence, which is also applied to evaluate online the growth in lateral size of damage sites under successive irradiation. 10,11) Many time-resolved microscope methods are also presented to study the laser damage growth based on the lateral shadowgraphy images. 12,13) Though the differential interference contrast mode of the optical microscope can be applied to analyze qualitatively the depth of damage sites, other off-line techniques are necessary to quantitatively evaluate the damage growth behavior of optical components.…”

“…The phase information can be indirectly measured by some interferometers, such as lateral shearing interferometers and digital holographic interferometers. 10,14,15) These interferometers have been successfully applied to measure and analyze the characteristics of the object according to the phase and amplitude information of interferograms, including surface shapes, living cells, phase defects, particles, tear topography features, and so on. [16][17][18][19][20][21][22][23][24][25] Therefore, the lateral size and the depth of damage sites can be obtained through the analysis of the interferogram.…”