Current 3-ω large optic test procedures and data analysis for the quality assurance of National Ignition Facility optics

Schwartz, Sheldon; Feit, Michael D.; Kozlowski, Mark R.; Mouser, Ron P.

doi:10.1117/12.344417

Cited by 17 publications

(7 citation statements)

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“…Large area damage testing 24 was conducted using a frequency-tripled Spectra-Physics Nd:YAG laser operating at 355nm with a 7.5-nsec temporal system pulse width and a spot size of ~1mm. Peak laser fluence was determined using the peak fluence measured for a Gaussian-shaped beam spot scaled from the system temporal pulse width to an equivalent 3nsec wide pulse by τ 1/2 scaling, where τ represents the ratio of the pulse lengths.…”

Section: Methodsmentioning

confidence: 99%

“…The peak probe fluence was held within +/-5 % of target via computer control of the laser system's energy attenuator. Damage detection and quantification was accomplished by side lighting the optic with white light and imaging the area of optic being damage tested onto a scanning linear CCD mega-pixel array 24 . This diagnostic enabled a digital micrograph to be generated of the area under test that highlighted defects within the bulk and on the optic surface with a resolution of 80-µm/pixel and 10-µm sensitivity.…”

Section: Methodsmentioning

confidence: 99%

“…The digital micrograph was subsequently analyzed and defects identified via threshold image processing and counting techniques. The area scaling approach described by Schwartz, et al 24 , was not used due to the difficulty in selecting Weibull coefficients when no damage can be observed in the tested area. All values are therefore reported as raw, uncorrected damage densities.…”

Section: Methodsmentioning

confidence: 99%

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Combined advanced finishing and UV-laser conditioning for producing UV-damage-resistant fused silica optics

Menapace

Penetrante

Miller

et al. 2002

Optical Fabrication and Testing

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Laser induced damage initiation on fused silica optics can limit the lifetime of the components when used in high power UV laser environments. Foe example in inertial confinement fusion research applications, the optics can be exposed to temporal laser pulses of about 3-nsec with average fluences of 8 J/cm 2 and peak fluences between 12 and 15 J/cm 2. During the past year, we have focused on optimizing the damage performance at a wavelength of 355-nm (3ω), 3-nsec pulse length , for optics in this category by examining a variety of finishing technologies with a challenge to improve the laser damage initiation density by at least two orders of magnitude. In this paper, we describe recent advances in improving the 3ω damage initiation performance of laboratory-scale zirconium oxide and cerium oxide conventionally finished fused silica optics via application of processes incorporating magnetorheological finishing (MRF), wet chemical etching, and UV laser conditioning. Details of the advanced finishing procedures are described and comparisons are made between the procedures based upon large area 3ω damage performance, polishing layer contamination, and optical subsurface damage.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Combined advanced finishing and UV-laser conditioning for producing UV-damage-resistant fused silica optics

Menapace

Penetrante

Miller

et al. 2002

Optical Fabrication and Testing

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show abstract

“…The LAT beam size is nominally 0.8 mm FWHM with a pulse duration of 7.5 ns and a repetition rate of 10 Hz; the LAT laser laboratory has been described in detail previously. 12 The laser fluence will be reported here in terms of the 3-ns equivalent fluence, using τ 1/2 pulse length scaling. The sample is raster scanned with the laser beam using a 50% overlap between successive shots.…”

Section: Methodsmentioning

confidence: 99%

UV-laser conditioning for reduction of 351-nm damage initiation in fused silica

et al. 2002

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“…With these tools we can detect damage and defects down to the micron scale. We have also developed new testing methods that no longer rely on the earlier concept of a "damage threshold" but instead treats damage as a probabilistic process [113,114] . The use of a probabilistic approach is essential when attempting to quantify the damage resistance of thousands of square meters of finished or coated surfaces and hundreds of metric tons of bulk optical materials assembled on the NIF.…”

Section: Improving Optics Lifetimementioning

confidence: 99%

NIF optical materials and fabrication technologies: an overview

et al. 2004

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The high-energy/high-power section of the NIF laser system contains 7360 meter-scale optics. Advanced optical materials and fabrication technologies needed to manufacture the NIF optics have been developed and put into production at key vendor sites. Production rates are up to 20 times faster and per-optic costs 5 times lower than could be achieved prior to the NIF. In addition, the optics manufactured for NIF are better than specification giving laser performance better than the design. A suite of custom metrology tools have been designed, built and installed at the vendor sites to verify compliance with NIF optical specifications. A brief description of the NIF optical wavefront specifications for the glass and crystal optics is presented. The wavefront specifications span a continuous range of spatial scale-lengths from 10 µm to 0.5 m (full aperture). We have continued our multi-year research effort to improve the lifetime (i.e. damage resistance) of bulk optical materials, finished optical surfaces and multi-layer dielectric coatings. New methods for post-processing the completed optic to improve the damage resistance have been developed and made operational. This includes laser conditioning of coatings, glass surfaces and bulk KDP and DKDP and well as raster and full aperture defect mapping systems. Research on damage mechanisms continues to drive the development of even better optical materials.

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Current 3-ω large optic test procedures and data analysis for the quality assurance of National Ignition Facility optics

Cited by 17 publications

References 0 publications

Combined advanced finishing and UV-laser conditioning for producing UV-damage-resistant fused silica optics

Combined advanced finishing and UV-laser conditioning for producing UV-damage-resistant fused silica optics

UV-laser conditioning for reduction of 351-nm damage initiation in fused silica

NIF optical materials and fabrication technologies: an overview

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