scholarly journals Detection Of Surface Defects And Subsurface Defects Of Polished Optics With Multisensor Image Fusion

2022 ◽  
Author(s):  
Huanyu Sun ◽  
Shiling Wang ◽  
Xiaobo Hu ◽  
Hongjie Liu ◽  
Xiaoyan Zhou ◽  
...  
Keyword(s):  
Image Fusion ◽  
Surface Defects ◽  
Damage Threshold ◽  
Dark Field ◽  
Image Sensors ◽  
Laser Damage Threshold ◽  
Material Surface ◽  
Wide Field ◽  
And Control ◽  
Subsurface Defects

Abstract Surface defects (SDs) and subsurface defects (SSDs) are the key factors decreasing the laser damage threshold of optics. Due to the spatially stacked structure, accurately detecting and distinguishing them has become a major challenge. Herein a detection method for SDs and SSDs with multisensor image fusion is proposed. The optics is illuminated by a laser under dark field condition, and the defects are excited to generate scattering and fluorescence lights, which are received by two image sensors in a wide-field microscope. With the modified algorithms of image registration and feature-level fusion, different types of defects are identified and extracted from the scattering and fluorescence images. Experiments show that two imaging modes can be realized simultaneously by multisensor image fusion, and HF etching verifies that SDs and SSDs of polished optics can be accurately distinguished. This method provides a more targeted reference for the evaluation and control of the defects of optics, and exhibits potential in the application of material surface research.

Anisotropic ion beam etching of fused silica to mitigate subsurface damage

2020 ◽  
Vol 34 (08) ◽  
pp. 2050060 ◽  
Author(s):  
Bo Li ◽  
Xia Xiang ◽  
Chengxiang Tian ◽  
Chunyuan Hou ◽  
Wei Liao ◽  
...  
Keyword(s):  
Surface Quality ◽  
Surface Defects ◽  
Silica Surface ◽  
Incident Angle ◽  
Ion Beam ◽  
Damage Threshold ◽  
Fused Silica ◽  
Laser Damage Threshold ◽  
Laser Damage ◽  
Ion Beam Etching

The laser damage resistance of fused silica optics depends significantly on the surface quality. In this work, anisotropic etching with inert ion beams at various ion incident angles was performed to investigate the evolution of the fused silica surface. The results show that the surface is smoothed when the incident angle is below [Formula: see text]. However, the fused silica surface starts to become coarse owing to the formation of nanostructures on the surface when the incident angle exceeds [Formula: see text]. Further, ion beam etching at a large incident angle of [Formula: see text] removes subsurface defects and less induces nanostructures, resulting in reduction of the surface roughness. The concentrations of impurities and defects are both significantly reduced after ion beam etching. The surface quality, subsurface and surface defects, and surface impurities determine the variation in the laser damage threshold of fused silica with the ion incident angle. The results demonstrate successful application of ion beam etching to improve the laser damage resistant characteristics of fused silica optics. Ion beam etching is a very versatile tool that provides physical erosion to anisotropically mitigate surface damage of fused silica.

Simulation ofmicro-nano processing induced surface defects influencing KDP laser damage threshold

2010 ◽  
Vol 22 (1) ◽  
pp. 159-164 ◽  
Author(s):  
陈明君 Chen Mingjun ◽  
姜伟 Jiang Wei ◽  
庞启龙 Pang Qilong ◽  
刘新艳 Liu Xinyan
Keyword(s):  
Surface Defects ◽  
Damage Threshold ◽  
Laser Damage Threshold ◽  
Laser Damage

Bulk Laser Damage Threshold and Stimulated Raman Scattering in KTiOPO4 Crystal.

1996 ◽  
Vol 24 (8) ◽  
pp. 906-909
Author(s):  
Akio MIYAMOTO ◽  
Hidetsugu YOSHIDA ◽  
Yusuke MORI ◽  
Takatomo SASAKI ◽  
Sadao NAKAI
Keyword(s):  
Raman Scattering ◽  
Stimulated Raman Scattering ◽  
Damage Threshold ◽  
Laser Damage Threshold ◽  
Laser Damage ◽  
Stimulated Raman

scholarly journals Laser-induced damage thresholds of ultrathin targets and their constraint on laser contrast in laser-driven ion acceleration experiments

2020 ◽  
Vol 8 ◽  
Author(s):  
Dahui Wang ◽  
Yinren Shou ◽  
Pengjie Wang ◽  
Jianbo Liu ◽  
Zhusong Mei ◽  
...  
Keyword(s):  
Damage Threshold ◽  
Wide Band ◽  
Laser Pulses ◽  
Laser Damage Threshold ◽  
Single Shot ◽  
Bulk Materials ◽  
Free Standing ◽  
Wide Band Gap ◽  
Different Types ◽  
Laser Induced Damage

Abstract Single-shot laser-induced damage threshold (LIDT) measurements of multi-type free-standing ultrathin foils were performed in a vacuum environment for 800 nm laser pulses with durations τ ranging from 50 fs to 200 ps. The results show that the laser damage threshold fluences (DTFs) of the ultrathin foils are significantly lower than those of corresponding bulk materials. Wide band gap dielectric targets such as SiN and formvar have larger DTFs than semiconductive and conductive targets by 1–3 orders of magnitude depending on the pulse duration. The damage mechanisms for different types of targets are studied. Based on the measurement, the constrain of the LIDTs on the laser contrast is discussed.

Improving the performance of high-laser-damage-threshold, multilayer dielectric pulse-compression gratings through low-temperature chemical cleaning

2013 ◽  
Vol 52 (8) ◽  
pp. 1682 ◽  
Author(s):  
Heather P. Howard ◽  
Anthony F. Aiello ◽  
Justin G. Dressler ◽  
Nicholas R. Edwards ◽  
Terrance J. Kessler ◽  
...  
Keyword(s):  
Low Temperature ◽  
Pulse Compression ◽  
Damage Threshold ◽  
Laser Damage Threshold ◽  
Laser Damage ◽  
Chemical Cleaning ◽  
High Laser ◽  
Multilayer Dielectric

scholarly journals Titanium-Based Microbolometers: Control of Spatial Profile of Terahertz Emission in Weak Power Sources

2020 ◽  
Vol 10 (10) ◽  
pp. 3400
Author(s):  
Linas Minkevičius ◽  
Liang Qi ◽  
Agnieszka Siemion ◽  
Domas Jokubauskis ◽  
Aleksander Sešek ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Dark Field ◽  
Spatial Mode ◽  
Contrast Imaging ◽  
Optical Components ◽  
Broadband Antenna ◽  
Power Sources ◽  
Precise Control ◽  
Imaging And Spectroscopy ◽  
And Control

Terahertz (THz) imaging and spectroscopy set-ups require fine optical alignment or precise control of spatial mode profile. We demonstrate universal, convenient and easy-to-use imaging—resonant and broadband antenna coupled ultrasensitive titanium-based—dedicated to accurately adjust and control spatial mode profiles without additional focusing optical components of weak power THz sources. Versatile operation of the devices is shown using different kinds of THz—electronic multiplier sources, optical THz mixer-based frequency domain and femtosecond optoelectronic THz time-domain spectrometers as well as optically pumped molecular THz laser. Features of the microbolometers within 0.15–0.6 THz range are exposed and discussed, their ability to detect spatial mode profiles beyond the antennas resonances, up to 2.52 THz, are explored. Polarization-sensitive mode control possibilities are examined in details. The suitability of the resonant antenna-coupled microbolometers to resolve low-absorbing objects at 0.3 THz is revealed via direct, dark field and phase contrast imaging techniques as well.

Modeling of femtosecond laser damage threshold on the two-layer metal films

2010 ◽  
Vol 257 (5) ◽  
pp. 1678-1683 ◽  
Author(s):  
A.M. Chen ◽  
H.F. Xu ◽  
Y.F. Jiang ◽  
L.Z. Sui ◽  
D.J. Ding ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Damage Threshold ◽  
Metal Films ◽  
Laser Damage Threshold ◽  
Laser Damage
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