Nif Small Optics Laser Damage Test Specifications PDF Download

The NIF injection laser system requires over 8000 precision optical components. Two special requirements for such optics are wavefront and laser damage threshold. Wavefront gradient is an important specification on the NIF ILS optics. The gradient affects the spot size and, in the second order, the contrast ratio of the laser beam. Wavefront errors are specified in terms of peak-to-valley, rms, and rms gradient, with filtering requirements. Typical values are lambda/8 PV, lambda/30 rms, and lambda/30/cm rms gradient determined after filtering for spatial periods greater than 2 mm. One objective of this study is to determine whether commercial software supplied with common phase measuring interferometers can filter, perform the gradient analysis, and produce numbers comparable to that by CVOS, the LLNL wavefront analysis application. Laser survivability of optics is another important specification for the operational longevity of the laser system. Another objective of this study is to find alternate laser damage test facilities. The addition of non-NIF testing would allow coating suppliers to optimize their processes according to their test plans and NIF integrators to validate the coatings from their sub-tiered suppliers. The maximum level required for anti-reflective, 45-degree high reflector, and polarizer coatings are 20, 30, and 5 J/cm2 (1064 nm, 3 ns pulse-width), respectively. The damage threshold correlation between a common set of samples tested by LLNL and a commercial test service is given.