Subsurface damage and polishing compound affect the 355-nm laser damage threshold of fused silica surfaces

Camp, David W.; Kozlowski, Mark R.; Sheehan, Lynn Matthew; Nichols, Michael A.; Dovik, M.; Raether, Robert G.; Thomas, Ian M.

doi:10.1117/12.307044

Cited by 97 publications

(48 citation statements)

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“…Camp et al 11 found that subsurface damage affected the LIDT of fused silica, but also found that RMS roughness was only weakly linked to subsurface damage and was not a good indicator of LIDT. The surface flatness measurements were used as a general indicator of surface quality.…”

Section: Sample Preparationmentioning

confidence: 99%

“…Magee et al 15 have shown that PBS measurements are linked to both subsurface defects and laser damage in fused silica. The penetration depth of the PBS laser was estimated to be 0.05 μm in ZGP, 14 which is within the uppermost 'polished' defect layer which can extend from 0.1 to 1 μm according to Camp et al 11 Subsurface defects from polishing/grinding are estimated to extend to depths up to 100 μm and deformed or strained layers are estimated to extend to depths of 200 μm. 11 The relatively shallow penetration depth made the PBS measurements much more of an indicator of surface scatter rather than subsurface defects in ZGP.…”

Section: Sample Preparationmentioning

confidence: 99%

“…RMS surface roughness has been linked by varying degrees to LIDT. [9][10][11][12][13] House et al 9 found that RMS surface roughness was a good indicator of the LIDT of fused silica, and more recently Randi et al 10 have found that RMS surface roughness was a good indicator of the depth of subsurface damage caused by polishing in some single crystalline optical materials, including:…”

Section: Sample Preparationmentioning

confidence: 99%

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Increasing the laser-induced damage threshold of single-crystal ZnGeP_2

et al. 2006

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information AFRL-ML-WP-TP-2007-418 SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING AGENCY ACRONYM(S) AFRL-ML-WP Materials and Manufacturing Directorate Air Force Research Laboratory Air Force Materiel Command Wright-Patterson AFB, OH 45433-7750 SPONSORING/MONITORING AGENCY REPORT NUMBER(S) AFRL-ML-WP-TP-2007-418 DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution unlimited. SUPPLEMENTARY NOTESJournal article submitted to Journal of the Optical Society of America B. The U.S. Government is joint author of this work and has the right to use, modify, reproduce, release, perform, display, or disclose the work. PAO Case Number: AFRL/WS 06-0773, 22 Mar 2006. This paper contains color content. ABSTRACTThe laser induced damage threshold (LIDT) of single crystal zinc germanium phosphide (ZGP), ZnGeP 2 , was increased to 2 J/cm 2 at 2.05 μm and 10 kHz pulse rate frequency (double the previously measured value of 1 J/cm 2 ). This increased LIDT was achieved by improving the polishing of ZGP OPO crystals. The surface preparation of ZGP samples was determined to be of great importance because laserinduced damage has been observed to always initiate at the surface rather than in the bulk of the material. Two different polishing techniques were evaluated by comparing the surfaces of ZGP samples fabricated in the same manner apart from the polishing stage. Surfaces were characterized using scanning white light interferometry (SWLI) in order to determine RMS surface roughness and sample flatness. The photon backscatter technique (PBS) was used to determine the degree of surface and subsurface damage in the sample induced through the fabrication process. Both uncoated and anti-reflection coated samples were damage tested. The effect of subsurface damage in the samples was studied by removing different amounts of material during polishing for otherwise identical samples. The amount of material removed was correlated to the observed LIDT. Statistical LIDT was measured using a high-average-power, repetitively Q-switched Tm,Ho:YLF 2.05-μm pump laser. On average, lower surface roughness and photon backscatter measurements was a good indicator of ZGP samples exhibiting higher LIDT. The removal of more material during polishing significantly improved the LIDT of otherwise identical samples, indicating the importance of subsurface damage defects in the LIDT of ZGP. SUBJECT TERMSlaser induced damage threshold, mid-infrared materials, non-linear ...

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Section: Sample Preparationmentioning

confidence: 99%

Section: Sample Preparationmentioning

confidence: 99%

Section: Sample Preparationmentioning

confidence: 99%

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Increasing the laser-induced damage threshold of single-crystal ZnGeP_2

et al. 2006

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“…In addition to the mechanical damage itself, such surface and subsurface cracks can serve as sites that can trap optically absorbing species, such as iron, ceria, and other contaminants, which are typically present in the polishing process. While improvement in damage initiation density can be realized by utilizing zirconia-based polishing slurries 13 , conventional lap polishing inevitably results in both surface and subsurface mechanical damage due to the high normal loads present from the weight of the optic on the lap bed. Because of this, the subsurface damage layer persists regardless of how careful one is in controlling the process.…”

Section: Laser Resistant Large-aperture Opticsmentioning

confidence: 99%

Developing magnetorheological finishing (MRF) technology for the manufacture of large-aperture optics in megajoule class laser systems

Menapace

2010

SPIE Proceedings

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Over the last eight years we have been developing advanced MRF tools and techniques to manufacture meter-scale optics for use in Megajoule class laser systems. These systems call for optics having unique characteristics that can complicate their fabrication using conventional polishing methods. First, exposure to the high-power nanosecond and sub-nanosecond pulsed laser environment in the infrared (>27 J/cm 2 at 1053 nm), visible (>18 J/cm 2 at 527 nm), and ultraviolet (>10 J/cm 2 at 351 nm) demands ultra-precise control of optical figure and finish to avoid intensity modulation and scatter that can result in damage to the optics chain or system hardware. Second, the optics must be super-polished and virtually free of surface and subsurface flaws that can limit optic lifetime through laser-induced damage initiation and growth at the flaw sites, particularly at 351 nm. Lastly, ultra-precise optics for beam conditioning are required to control laser beam quality. These optics contain customized surface topographical structures that cannot be made using traditional fabrication processes. In this review, we will present the development and implementation of large-aperture MRF tools and techniques specifically designed to meet the demanding optical performance challenges required in largeaperture high-power laser systems. In particular, we will discuss the advances made by using MRF technology to expose and remove surface and subsurface flaws in optics during final polishing to yield optics with improve laser damage resistance, the novel application of MRF deterministic polishing to imprint complex topographical information and wavefront correction patterns onto optical surfaces, and our efforts to advance the technology to manufacture largeaperture damage resistant optics.

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“…It is a fact that laser-induced damage of AR coatings was a limiting factor on reliable operation of such high-power solid-state lasers. Many studies on how to improve transmittance element damage threshold have been carried out over the past decades years [5][6][7][8]. Among these studies, understanding the origin and mechanisms of laser-induced damage was important for the improvement of the laser radiation resistivity of the AR coatings.…”

Section: Introductionmentioning

confidence: 99%

Study for Improvement of Laser Induced Damage of 1064 nm AR Coatings in Nanosecond Pulse

Jiao¹,

Cheng²,

Li³

et al. 2013

Journal of the Optical Society of Korea

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For the conventionally polished fused silica substrate, an around 100 nm depth redeposition polishing layer was formed on the top of surface. Polishing compounds, densely embedded in the redeposition polishing layer were the dominant factor that limited the laser induced damage threshold (LIDT) of transmission elements in nanosecond laser systems. Chemical etching, super-precise polishing and ion beam etching were employed in different ways to eliminate these absorbers from the substrate. After that, Antireflection (AR) coatings were deposited on these substrates in the same batch and then tested by 1064 nm nano-pulse laser. It was found that among these techniques only the ion beam etching method, which can effectively remove the polishing compound and did not induce extra absorbers during the disposal process, can successfully improve the LIDT of AR coatings.

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Subsurface damage and polishing compound affect the 355-nm laser damage threshold of fused silica surfaces

Cited by 97 publications

References 0 publications

Increasing the laser-induced damage threshold of single-crystal ZnGeP_2

Increasing the laser-induced damage threshold of single-crystal ZnGeP_2

Developing magnetorheological finishing (MRF) technology for the manufacture of large-aperture optics in megajoule class laser systems

Study for Improvement of Laser Induced Damage of 1064 nm AR Coatings in Nanosecond Pulse

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