Laser induced damage testing: Equipment and techniques
Abstract
A laser damage test station was designed and built at the AlliedSignal Inc., Kansas City Division (KCD). The purpose of this effort was to establish the capability for testing polished optical fibers for high energy laser transmission to support the Direct Optical Initiation (DOI), optical firing-set program. A single shot, conditioned threshold type laser damage test was implemented. A flashlamp pumped, multimode, Q-switched, Nd:YAG laser was utilized as the test source. The test laser's operational parameters were extensively characterized. The pulse width, beam divergence, and polarization state of the laser were all held constant throughout the tests. A single plano-convex lens was utilized to focus the laser beam energy into the optical fibers. A focusing geometry was utilized which avoided bulk damage and minimized damage at the fiber's core/cladding interface. A special holding fixture was fabricated, which minimized the mechanical stresses on the fiber during testing. Several uncoated, step-index, multimode, optical fibers were damage tested to verify the functionality of the test station. The fibers all had a 400 micron diameter core of pure fused silica, a 440 micron diameter fluorine doped fused silica cladding, and a 15 micron thick polyimide buffer layer. The fibers were tested up to a fluence level greater than 55.7 J/cm(exp 2) or until damage was observed. Cleaning, inspection, and testing procedures were developed and documented.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- July 1993
- Bibcode:
- 1993STIN...9418060M
- Keywords:
-
- Destructive Tests;
- Laser Beams;
- Laser Damage;
- Measuring Instruments;
- Optical Fibers;
- Silica Glass;
- Glass Fibers;
- Neodymium Lasers;
- Q Switched Lasers;
- Radiation Effects;
- Lasers and Masers