Laser-induced contamination of silica coatings in vacuum

Becker, S.; Pereira, Alexandre; Bouchut, Philippe; Geffraye, F.; Anglade, C.

doi:10.1117/12.696042

Cited by 16 publications

(17 citation statements)

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“…Nitrogen and toluene do not affect the breakdown threshold F(∞). The outcome with toluene is very different from the observation with ns pulses, where organic compounds formed graphitic deposits that accelerated failure [5,7]. Figure 3 shows that F(∞) is sensitive to both the pressure of water vapor and gaseous oxygen.…”

Section: Methodsmentioning

confidence: 88%

“…Previous studies with nanosecond lasers under vacuum and sealed atmospheric conditions have shown that the useful lifetime of the optics and multiple pulse damage fluence reduced significantly for dielectric films [5][6][7][8] and bulk materials [9,10] compared to atmospheric conditions. Two explanations have been given for these observations.…”

Section: Introductionmentioning

confidence: 99%

“…In both cases, the effects of ambient gas on the laser damage threshold are more prominent in films prepared by electron-beam evaporation. When using high-density films such as those prepared by ion-assisted deposition, the deposition rate of graphite is reduced by a factor of 50 [5] and the effect of water eliminated [8].…”

Section: Introductionmentioning

confidence: 99%

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Femtosecond pulse damage thresholds of dielectric coatings in vacuum

Nguyễn¹,

Emmert²,

Schwoebel³

et al. 2011

Opt. Express

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At 10 -7 Torr, the multiple femtosecond pulse damage threshold, F(∞), is about 10% of the single pulse damage fluence F(1) for hafnia and silica films compared to about 65% and 50%, respectively, at 630 Torr. In contrast, the single-pulse damage threshold is pressure independent. The decrease of F(∞) with decreasing air pressure correlates with the water vapor and oxygen content of the ambient gas with the former having the greater effect. The decrease in F(∞) is likely associated with an accumulation of defects derived from oxygen deficiency, for example vacancies. From atmospheric air pressure to pressures of ~3x10 -6 Torr, the damage "crater" starts deterministically at the center of the beam and grows in diameter as the fluence increases. At pressure below 3x10 -6 Torr, damage is initiated at random "sites" within the exposed area in hafnia films, while the damage morphology remains deterministic in silica films. A possible explanation is that absorbing centers are created at predisposed sample sites in hafnia, for example at boundaries between crystallites, or crystalline and amorphous phases.

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Section: Methodsmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Femtosecond pulse damage thresholds of dielectric coatings in vacuum

Nguyễn¹,

Emmert²,

Schwoebel³

et al. 2011

Opt. Express

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“…Laser-Induced Contamination is a known phenomenon responsible for the degradation of the properties of optical components in vacuum [1] [2] [3]. Such degradation is due to the formation of a deposit in the optical surface area irradiated by the UV laser beam under vacuum (see Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Laser-induced contamination control for high-power lasers in space-based LIDAR missions

Alves

Pettazzi

Tighe

et al. 2017

International Conference on Space Optics — ICSO 2010

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In the framework of the ADM-Aeolus satellite mission, successful test campaigns have been performed in ESTEC's laser laboratory, and the efficiency of several mitigation techniques against Laser-Induced Contamination (LIC) have been demonstrated for the ALADIN laser. These techniques include the standard contamination control methods of materials identification with particular tendency to cause LIC, reduction of the outgassing of organic materials by vacuum bake-out and shielding of optical surfaces from the contamination sources. Also novel mitigation methods such as in-situ cleaning via partial pressures, or the usage of molecular absorbers were demonstrated. In this context, a number of highly sensitive optical measurement techniques have been developed and tested to detect and monitor LIC deposits at nanometre level.

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“…[3] The performance of coatings is affected by the built-up of contamination under high fluence irradiation in vacuum. [4,5] Still, there is a lack of understanding of damage characteristics of dielectric optics exposed to vacuum.…”

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confidence: 99%