Fused Silica

Fused silica is an ideal optical material for many applications. It is transparent over a wide spectral range, has a low coefficient of thermal expansion, and is resistant to scratching and thermal shock. Fused silica is formed by chemical combination of silicon and oxygen. Advantages of fused silica material include good UV and IR transmission, low coefficient of thermal expansion, providing stability and resistance to thermal shock over large temperature excursions, wider thermal operating range and high laser damage threshold. Used for windows, lenses, prisms and mirror substrates.

Synthetic fused silica is far purer than fused quartz. This increased purity ensures higher ultraviolet transmission and freedom from striae or inclusions. The synthetic fused-silica materials used by Dream Lasers are manufactured by flame hydrolysis to extremely high standards. The resultant material is colorless and non-crystalline, and it has an impurity content of only about one part per million. Controlling the purity of reactants and the conditions of reaction ensures the high quality of the synthetic fused silica from which our lenses are made.

Optical-qualit synthetic fused silica lenses are ideally suited for applications in energy-gathering and imaging systems in the mid-ultraviolet, visible, and near-infrared spectral regions. The low dispersion of fused silica reduces chromatic aberration.

UV-grade synthetic fused silica is selected to offer the highest transmission (especially in the deep ultraviolet) and very low fluorescence levels (approximately 0.1% that of fused natural quartz excited at 254 nm). UV-grade synthetic fused silica does not fluoresce in response to wavelengths longer than 290 nm. In deep ultraviolet applications, UV-grade synthetic fused silica is an ideal choice. Its tight index tolerance ensures highly predictable lens specifications.

Fused Silica Constants
Abbé Constant
67.8 ± 0.5
Change of Refractive Index with Temperature (0° to 700°C)
1.28 x 10-5/°C
Homogeneity (maximum index variation over 10-cm aperture)
2 x 10-5
Density (25°C)
2.20 g cm-3
Continuous Operating Temperature
Maximum 900°C
Coefficient of Thermal Expansion
5.5 x 10-7°C
Specific Heat (25°C)
0.177 cal/g°C
Dispersion Constants
B1 = 0.6961663
B2 =0.4079426

B3 =0.8974794
C1 = 0.0684043
C2 = 0.1162414
C3 = 9.896161
The external transmittance of Fused Silica is shown in the figure below:
External transmittances for UV-grade and optical grade fused silica