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Bk7 Optical Glass

BK7 Optical Properties
Thermal Properties
Thermal Coefficient of Expansion (0/300°C): 70 X 10 -7/°C
Annealing Point 550°C / 1022 °F
Softening Point 719°C / 1326 °F
Strain Point 624°C / 1155 °F

Mechanical Properties
Density 2.51 g/cm3
Knoop Hardness 610
Young's Modulus 8.20 X 109 dynes/mm2
Poisson's Ratio .206

Optical Properties
Refractive Index 1.509

Chemical Properties
Hydrolytic Resistance class 2
Acid Resistance class 1
Alkali Resistance class 1