Skip to Main Content
A synthetic ruby crystal observed in cross section by laser interferometer techniques shows high contrast of optical fringes, also visible in the background. The 6-inch-long rod has a ½-inch diameter; it was inspected with a Perkin-Elmer instrument consisting of a gas laser that emits continuous coherent light at 6328 Å and a modified Twyman-Green interferometer. The instrument has enabled inspection of optical materials with double or more the accuracy previously obtainable, and in some cases it permits studies never before undertaken. The laser's beam can produce 3000 times more useful light energy than an arc light.