custom telescope mirror blanks borosilicate glass

A particularly low coefficient of thermal expansion is what makes BOROFLOAT® glass remarkably resistant to high temperature levels. Our borosilicate glass is proven to stand up to high and fluctuating temperatures typical of applications such as high-performance lamps, cinema projectors and inspection panels for chemical reactors. Even with applications where rapid cooling down from higher temperatures is the requirement, BOROFLOAT® glass easily passes the test. For example, the temperature difference between a hot panel center and a cold panel edge.

Outstanding thermal resistance
Very good temperature stability
Excellent resistance to thermal shock
Can be thermally toughened
Can be thermally shaped (3D)

Exceptionally high transparency
 High transparency in visible and near IR & UV range of wavelengths
 Outstanding visual quality and optical clarity
 Low inherent fluorescence and solarisation tendency

Thermal properties
Coefficient of Linear Thermal Expansion (C.T.E.) α (20 - 300 °C) 3.25 x 10-6 K-1 *
Specific heat capacity cp (20 - 100 °C) 0.83 kJ/(kg·K)-1
Thermal conductivity λ (90 °C) 1.2 W/(m·K)-1

* According to ISO 7991.
Maximum operating temperatures
For short-term usage (< 10 h) 500 °C
For long-term usage (≥ 10 h) 450 °C
Viscosity of BOROFLOAT® 33
Working Point (104 dPas) 1270 °C
LITTLETON temperature / Softening Point (107,6dPas) 820 °C
Annealing Point (1013 dPas) 560 °C
Strain Point (1014,5 dPas) 518 °C
Transformation temperature (Tg) 525 °C

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Sales manager:Spring Lin