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. UV Grade Fused Silica: JGS1 (Chinese), equivalent to Suprasil 1 and 2 (Heraeus), Spectrosil A and B (Saint-Gobain) and Corning 7940 (Corning), Dynasil 1100 and 4100 (Dynasil). Optical Grade Fused Quartz: JGS2 (China), equivalent to Homosil 1, 2 & 3 (Heraeus), Dynasil 1000 & 4000 and 5000 & 6000 (Dynasil) IR grade Fused Silica: JGS3 (China), equivalent to Suprasil 300 (Heraeus). UV grade Fused Silica (JGS1) is synthetic amorphous silicon dioxide of extremely high purity. This non-crystalline, colorless silica glass combines a very low thermal expansion coefficient with good optical qualities, and excellent transmittance in the ultraviolet. Transmission and homogeneity exceed those of crystalline quartz without the problems of orientation and temperature instability inherent in the crystalline form. Fused silica is used for both transmissive and reflective optics, especially where high laser damage threshold is required. 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. 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. Optical Grade Fused Quartz (JGS2) 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) 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. Properties: Parameter JGS1 JGS2 JGS3 Maximum Size 90%) 0.26~2.10um (Tavg>85%) 0.25~3.50um (Tavg>85%) OH- Content 1200 ppm 150ppm 5ppm Fluorescence (ex 254nm) Virtually Free Strong v-b Strong v-b Impurity Content 5 ppm 20-40 ppm 40-50 ppm Birefringence Constant 2-4 nm/cm 4-6nm/cm 4-10nm/cm Melting Method Synthetic CVD Oxy-hydrogen melting Electrical melting Applications Laser substrate: Window,lens,prism, mirror, etc. Semiconductor and high temperature window IR substrate Hardness 5.5 - 6.5 Mohs' Scale 570 KHN 100 Design Tensile Strength 4.8x107 Pa (N/mm2) (7000 psi) Design Compressive Strength Greater than 1.1x109 Pa (160,000 psi) Bulk Modulus 3.7x1010 Pa (5.3x106 psi) Rigidity Modulus 3.1x1010 Pa (4.5x106 psi) Young's Modulus 7.2x10-10 Pa (10.5x106 psi) Poisson's Ratio 0.17 Constant Strength Loss Factor Dissipation Factor 3.75 5*107 V/m Less than 4x10-4 Less than 1x10-4 Velocity of Sound-Shear Wave 3.75*103 m/s Velocity of Sound/Compression Wave 5.90*103 m/s Sonic Attenuation Less than 11 db/m MHz Permeability Constants (cm3mm/cm2 sec cm of Hg) Helium Hydrogen Deuterium Neon 210x10-10 21x10-10 17x10-10 9.5x10-17 Chemical Stability (except hydrofluoric) High resistance to water and acids