Uncoated Substrates

OPTICAL MATERIALS

Synthetic Fused Silica

Any synthetic, amorphous form of silicon dioxide made by flame hydrolysis of silicon tetrachloride is referred to as fused silica. Fused silica is a useful glass because of its good UV and NIR transsmission, its high strength, its low coefficient of thermal expansion, and its high laser damage threshold.

Suprasil, SQ0 (1,2), C7940

Suprasil is a type of fused silica with high purity and excellent homogeneity. Suprasil has virtually no granularity or striae, and the index variation is less than 10 ppm. Because Suprasil has a metallic impurity content less than 8 ppm, the UV transmission is superior and fluorescence is minimal. Being fused silica, Suprasil exhibits high strength and low thermal expansion.

Infrasil, SP0 (1)

Infrasil is a type of fused quartz produced by electrically fusing high quality quartz crystals. Infrasil has three times higher metallic impurity than Suprasil, so it shows reduced UV transmission. However, Infrasil has a lower OH content than Suprasil, and consequently better IR transmission. Infrasil exhibits high strength and low thermal expansion and its homogeneity is better than that of Suprasil.

Sapphire

Sapphire is a synthetic, single crystal aluminium oxide. Because of its structure, it exhibits large optical anisotropy and the exact characteristics depend upon the orientation of the optical axis. Sapphire has five times the strength of fused silica and superior optical transmission in both the UV and the IR.

BK7

Zerodur

A glass ceramic product with a coefficient of expansion that is practically zero. Recommended uses include those requiring extremely temperature stable substrates such as interferometer mirrors.