The Antares laser system is a large (100 kJ) CO2 pulse laser operating at 10.6 pm. The system has 72 beam lines, each with an aperture of 900 cm2. The system will be composed primarily of large copper-faced mirrors whose principal dimensions range up to 65 cm. These mirrors will be single-point diamond turned (SPDT) at the Y-12 facility of Union Carbide Corporation in Oak Ridge, Tennessee. We have had to develop surface quality specifications for these mirrors. These specifications were initially set at 50 nm peak-to-valley (p-v) surface error for the microsurface over 0.5-mm areas and 500 nm (p-v) over the whole mirror surface. In this paper an attempt has been made to refine these specifications to a more phys-ically meaningful set based on the performance of the system. The optical specification for Antares is that 80% of the energy from each beam should be deliverable inside a 400-μm circle. The diffraction limited focal spot is 160 pm across, so small amounts of low spa-tial frequency wavefront aberrations are acceptable. This is the "figure error" and can be represented by a best-fit fourth-order polynomial. It is specified separately from the higher spatial frequency "subfigure" errors that diffract light out of the 400-μm circle. Antares will have a completely automatic alignment and centering system. A more versatile and less expensive alignment system can be developed if the alignment is done with visible light. This tightens the tolerances on the microsurface but not the figure error. These requirements, along with several lesser ones, must be considered when tolerancing the mirror quality. It appears that the SPDT mirrors turned at Y-12 will meet our minimum requirements.
W. C. Sweatt,
"Mirror Quality Required By The Antares Laser System", Proc. SPIE 0190, Los Alamos Conference on Optics 1979, (13 November 1980); doi: 10.1117/12.957745; https://doi.org/10.1117/12.957745