Design and Management of Stray Light for Compact Final Optics Assembly on the High Energy Laser System

Figure 1

Schematic of the optical configuration of compact FOA. Separated FOA pulls large spacing from crystal to WFL to reduce the crosstalk of stray light and concentrate stray light. Moreover, it puts the crystal and WFL in atmosphere to delay the chemical film degradation and minimize out-gassing of organics. However, the risk of damage and crack of vacuum window increases sharply in separated FOA. The compact FOA avoids the risk of vacuum window cracking, but the small distance from the crystal to the focusing lens makes it more difficult to optimize the design and management of stray light.