Optical flat mirrors are manufactured using optical fused silica for extra thermal stability and are available coated or uncoated. These mirrors are suitable for the most demanding imaging systems, laser applications, as well as for holography, optical path folding, and as reflectors for auto-collimating requirements. The primary surface is precision ground and polished to the stated accuracy and certified by a Zygo GPI-XP Interferometer. The secondary surface is pitch polished to window quality.