Integrated photothermal microscope and laser damage test facility for in-situ investigation of nanodefect induced damage

Abstract

An integrated setup allowing high resolution photothermal microscopy and laser damage measurements at the same wavelength has been implemented. The microscope is based on photothermal deflection of a transmitted probe beam : the probe beam (633 nm wavelength) and the CW pump beam (1.06 microm wavelength) are collinear and focused through the same objective. In-situ laser irradiation tests are performed thanks to a pulsed beam (1.06 microm wavelength and 6 nanosecond pulse). We describe this new facility and show that it is well adapted to the detection of sub-micronic absorbing defects, that, once located, can be precisely aimed and irradiated. Photothermal mappings are performed before and after shot, on metallic inclusions in dielectric. Results obtained on gold inclusions of about 600 nm in diameter embedded in silica are presented.

Influence of oil contamination on the optical performance and laser induced damage of fused silica

“…It is based on photo-thermal deflection (PD) of the probe beam owing to laser absorption, which is related to local heating [17]. In this work, the absorption coefficient of clean pristine fused silica samples (A) and severely contaminated fused silica samples (G) at 355 nm were measured by a photo-thermal microscopy.…”

Detection of nanoscale defects in optical films by photothermal reflectance microscopy

“…Hence, accurate detection of the defects inside the optical material is crucial for preventing the laser-induced damage and securing high-power optical performance. Photothermal microscopy (PTM) is one of the most widely used optical techniques for nondestructive detection of the defects in optical materials that are responsible for laser damage [5][6][7][8][9][10]. In order to locate the defects, this technique utilizes a photothermally-induced refractive index gradient through laser absorption of the absorbing material (i.e., the thermal lens effect [11]).…”

Laser-induced damage threshold detection for optical thin films and research on damage morphology

“…The key of measuring laser-induced damage threshold is to accurately judge whether damage happens or not. At present, laser damage's testing methods include microscope observation [7] , plasma spark [8] , photo-thermal beam deflection [9] etc. Every method has its own advantages and disadvantages.…”