Property

Float glass (capillary glass)

Modified aluminosilicate glass

Density [kg/m3]

2500

2477

Bending tensile strength [N/mm2]

45

200

Young’s Modulus [N/mm2]

70,000

74,000

Middle thermal coefficient of expansion [1/K]

9.0 × 10−6

8.8 × 10−6

Refractive index

≈1.52

1.508