Optical quality fused silica (FS), UV grade fused silica (UV FS) and borosilicate crown glass are the materials used in the majority of EKSMA optical components. UV grade FS and borosilicate crown glass used by EKSMA conform the requirements for Shott Glass SUPRASIL and BK7 respectively. EKSMA occasionally uses corresponding glasses made by different glass manufacturers, but only when it does not result in a significant change of optical properties.

Fused Silica (FS)

Fused silica is an ideal optical material for many applications. It is extremely transparent over a wide spectral range, has a low coefficient of thermal expansion, and is resistant to scratching and thermal shock. When compared with glass or fused quartz, fused silica has a greater UV and IR transmission, wider thermal operating range, much higher resistance to radiation darkening from UV, X-rays and gamma rays. FS components are ideally suited for applications in energy-gathering and imaging systems in the mid-UV, VIS and near-IR spectral ranges. The low dispersion of FS reduces chromatic aberration.

Ultraviolet grade Fused Silica (UVFS)

UV grade fused silica offers both highest transmission (especially in deep-UV) and very low fluorescence levels (approximately 0.1% that of fused natural quartz). In deep-UV applications UV grade fused silica is an ideal choice. Its tight index tolerance assures highly predictable lens, window, prism, etc. specifications. Very low bubble content makes it really unique.

Borosilicate crown glass (BK7)

BK7 is a material used in a large fraction of EKSMA products. It is relatively hard glass, doesn’t scratch easily and can be handled without special precautions. The inclusion and bubble content of BK7 is very low: cross-section totally less than 0.03 mm² per 100 cm³. Another important feature of BK7 is its excellent transmission down to 350 nm. Due to these properties, including inexpensiveness, BK7 is used widely throughout the optics industry.

External transmittance curves of FS, UV FS and BK7 glass samples, 10 mm. thickness, uncoated