Testing and Process Protocols Improve the Reliability of HEL Optical Coatings

S2884 — HEL Optical Coating Reliability Improvement

Objective

High-reflectivity optical coatings intended for use in high energy laser (HEL)
systems must be highly reflective, have low absorption, and have a sufficiently low
stress to maintain wavefront specification. They must also have low defect
densities with small defect sizes to mitigate the potential risk of failure from
thermal runaway that can occur when a defect is exposed to high irradiance
levels. Optical coating failures in HEL systems can lead to time-consuming and
costly replacements that require skilled engineers and technicians. Prior testing
has shown that very small defects can induce catastrophic damage when exposed
to high-intensity laser light. As HEL weapon systems move toward Programs of
Record and installed onboard ships, such as the DDG 51 Class destroyer and the
FFG 62 Class frigate, a higher level of optical coating reliability will be essential.
This Electro-Optics Center (EOC) project will improve the reliability of HEL
weapon system optical components by understanding how coating defects impact
coating performance, developing coating process improvements to minimize such
defects while maintaining or improving optical properties, and resulting in
lower life-cycle costs and improved system availability. While this project
functions as a risk- reduction effort, it also supports the requirement for higher
laser power of future systems.

Payoff

Improved coating reliability will directly translate into improved HEL
weapons system reliability, resulting in increased availability and lower life-
cycle costs, primarily from reduced maintenance costs. Successful execution of
this Capability Acceleration project will result in advanced test protocols and
advanced metrology methods that ultimately support the production of coatings
with improved reliability for HEL weapons systems. The project also seeks to
demonstrate HEL coatings from a commercial supplier with higher reliability
than currently available for HEL weapon systems to achieve significant life-cycle
savings and to avoid lengthy repairs.

Implementation

The primary transition platforms for this project are the DDG 51 Class destroyer
and FFG 62 Class frigate. Implementation is expected to be achieved through
DoD use of the HEL coating specification and inspection protocols resulting from
phase one of the project. The improvements in the coating process to reduce
defects are expected to naturally transition as best practices to meet the HEL coating
requirements for the weapon system.