Our Clear Optical Path USAF targets are manufactured from an extremely thin electroformed nickel substrate. Since there is no glass in the pattern area, light travels only through air, eliminating chromatic and absorption issues. The target pattern covers from Group 0, Element 1 to Group 3, Element 6. A user card is included to illustrate where each group and element is located. Our UV Fused Silica & fluorescent USAF targets are available for most NUV applications, but the Clear Optical Path Target can be used for very deep UV and far-IR applications. The electroform pattern is mounted between two circular plates, allowing it to be mounted in our standard optic mount, #64-565.