Fused Silica

● Fused Silica

Fused Silica.pdf

Fused Silica is the glass form of quartz and is thus isotropic. It is tough, hard and has a very low expansion. Normal varieties contain water that gives strong absorption in the IR. Water-free varieties are availabl.
Fused Quartz is less expensive vitreous silica formed by fusing naturally occurring quartz crystal or lower grade synthetic stock material, The UV use is limited to 250nm and this material is usually used for windows covering visible wavelengths.
Fused Silica is vitreous silica formed by fusing high purity synthetic material. The UV use can be reached about 160nm.
Ultraviolet Grade Fused Silica: JGS1 (China), equivalent to Suprasil 1 and 2 (Heraeus), Spectrosil A and B (Saint-Gobain) and Corning 7940 (Corning), Dynasil 1100 and 4100 (Dynasil). It is transparent in the ultraviolet and visible regions, and has no absorption bands in the 170-250 nm wavelength intervals. It has an intensive OH absorption band in the interval of wavelength 2600-2800 nm. JGS1 is used for optics operating in the deep UV and the visible wavelength range (Laser Lenses, Windows, Prisms, Mirrors, etc.). It is practically free of bubbles and inclusions.
JGS1 is transparent in the ultraviolet and visible regions, and has no absorption bands in the 170-250 nm wavelength intervals. It has an intensive OH absorption band in the interval of wavelength 2600-2800 nm. Used for optics operating in the deep UV and the visible wavelength range (Laser Lenses, Windows, Prisms, Mirrors, etc.). It is practically free of bubbles and inclusions. 
Optical Grade Fused Quartz: JGS2 (China), equivalent to Homosil 1, 2 & 3 (Heraeus), Dynasil 1000 & 4000 and 5000 & 6000 (Dynasil). It provides good UV and visible transmission. It has almost the same physical and chemical properties with JGS1. However only in thin & small sheet pieces, JGS2 is virtually bubble-free. Elements built from larger pieces will most likely contain bubbles, so application should not be sensitive to these inclusions. But in cases where simple light gathering and strong mechanical properties are the primary goals, JGS2 grade provides excellent performance at a low price.
Ideal Applications for JGS2:
● Condenser optics not concerned with scatter or distortion
● High temperature and pressure applications
● Optical flats, microscope slides and sight glasses
IR grade Fused Silica: JGS3 (China), equivalent to Suprasil 300 (Heraeus). It is super purity synthetic fused silica manufactured by melting of super pure ash in vacuum. It is transparent in the ultraviolet, visible and infrared spectral regions. It has no absorption bands in the visible region and has no OH absorption band at 2700 nm ("water band").
JGS3 combines excellent physical properties with outstanding optical characteristics in the deep UV and the IR wavelength range. It is the preferred material for transmission optics; it is usually used in IR applications and also in those requiring very wide wavelength range from DUV to MIR. However the most common Fused Silica for infrared use is quite a bit more expensive than Silicon and slightly less expensive than Calcium Fluoride or ZnS Multi-spectral grade. Also a commercial quality of IR quartz often contains many small bubbles and should only be used for non-imaging applications.
Rising EO can handle with JGS1 well into 10-5 S/D and lambda/20 grade.