Mitigation of Laser Damage Growth in Fused Silica with a Galvanometer Scanned CO2 Laser

PDF Version Also Available for Download.

Description

At the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL), mitigation of laser surface damage growth on fused silica using single and multiple CO{sub 2} laser pulses has been consistently successful for damage sites whose lateral dimensions are less than 100 {micro}m, but has not been for larger sites. Cracks would often radiate outward from the damage when a CO{sub 2} pulse was applied to the larger sites. An investigation was conducted to mitigate large surface damage sites using galvanometer scanning of a tightly focused CO{sub 2} laser spot over an area encompassing the laser damage. It ... continued below

Physical Description

PDF-file: 12 pages; size: 5.4 Mbytes

Creation Information

Bass, I L; Guss, G M & Hackel, R P October 28, 2005.

Context

This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this article can be viewed below.

Who

People and organizations associated with either the creation of this article or its content.

Publisher

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this article. Follow the links below to find similar items on the Digital Library.

Description

At the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL), mitigation of laser surface damage growth on fused silica using single and multiple CO{sub 2} laser pulses has been consistently successful for damage sites whose lateral dimensions are less than 100 {micro}m, but has not been for larger sites. Cracks would often radiate outward from the damage when a CO{sub 2} pulse was applied to the larger sites. An investigation was conducted to mitigate large surface damage sites using galvanometer scanning of a tightly focused CO{sub 2} laser spot over an area encompassing the laser damage. It was thought that by initially scanning the CO{sub 2} spot outside the damage site, radiating crack propagation would be inhibited. Scan patterns were typically inward moving spirals starting at radii somewhat larger than that of the damage site. The duration of the mitigation spiral pattern was {approx}110 ms during which a total of {approx}1.3 J of energy was delivered to the sample. The CO{sub 2} laser spot had a 1/e{sup 2}-diameter of {approx}200 {micro}m. Thus, there was general heating of a large area around the damage site while rapid evaporation occurred locally at the laser spot position in the spiral. A 30 to 40 {micro}m deep crater was typically generated by this spiral with a diameter of {approx}600 {micro}m. The spiral would be repeated until there was no evidence of the original damage in microscope images. Using this technique, damage sites as large as 300 mm in size did not display new damage after mitigation when exposed to fluences exceeding 22 J/cm{sup 2} at 355 nm, 7.5 ns. It was found necessary to use a vacuum nozzle during the mitigation process to reduce the amount of re-deposited fused silica. In addition, curing spiral patterns at lower laser powers were used to presumably ''re-melt'' any re-deposited fused silica. A compact, shearing interferometer microscope was developed to permit in situ measurement of the depth of mitigation sites.

Physical Description

PDF-file: 12 pages; size: 5.4 Mbytes

Source

  • Presented at: Boulder Damage Symposium XXXVII, Boulder, CO, United States, Sep 19 - Sep 21, 2005

Language

Item Type

Identifier

Unique identifying numbers for this article in the Digital Library or other systems.

  • Report No.: UCRL-PROC-216737
  • Grant Number: W-7405-ENG-48
  • Office of Scientific & Technical Information Report Number: 883526
  • Archival Resource Key: ark:/67531/metadc892225

Collections

This article is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

What responsibilities do I have when using this article?

When

Dates and time periods associated with this article.

Creation Date

  • October 28, 2005

Added to The UNT Digital Library

  • Sept. 23, 2016, 2:42 p.m.

Description Last Updated

  • Nov. 29, 2016, 8:16 p.m.

Usage Statistics

When was this article last used?

Yesterday: 0
Past 30 days: 0
Total Uses: 2

Interact With This Article

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

Citations, Rights, Re-Use

Bass, I L; Guss, G M & Hackel, R P. Mitigation of Laser Damage Growth in Fused Silica with a Galvanometer Scanned CO2 Laser, article, October 28, 2005; Livermore, California. (digital.library.unt.edu/ark:/67531/metadc892225/: accessed October 18, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.