Mirrors specially designed for beam steering mirror stages with a flatness of λ/10 or better (λ is equal to 633 nm) and having any of the following: a. Diameter or major axis length greater than or equal to 100 mm; or b. Having all of the following: 1. Diameter or major axis length greater than 50 mm but less than 100 mm; and 2. A Laser Induced Damage Threshold (LIDT) being any of the following: a. Greater than 10 kW/cm 2 using a ‘CW laser’; or b. Greater than 20 J/cm 2 using 20 ns ‘laser’ pulses at 20 Hz repetition rate;