Sapphire (Single crystal Al2O3) is a commonly used optical material, mainly based on its several characteristics.
Ultra-long applicable wavelength band: it can transmit from ultraviolet (UV=150nm) wavelength to mid-infrared (IR=5um) wavelength, and has high transmittance
Excellent physical properties: including strength, high hardness, high temperature resistance, friction resistance, and corrosion resistance.
Stable chemical properties, such as not being corroded by acids and alkalis.
a = 4.758 Å
c = 12.991 Å
(1011), (1120) imperfect
Refractive Index at ne
Refractive Index at nF' - nC'
Thermal Coefficient of Refractive Index at 3.39 microns for ±60 °C
βo = (0.88 ... 1.28) x 10-5 βe = (0.99 ... 1.39) x 10-5
Spectral Range, microns
0.17 - 5.0
Thermal Linear Expansion, °C-1 for ±60 °C
⊥ to c-axis
(3.24 ... 5.66) x 10-6
Thermal Conductivity, W/(m * °C) at 46 °C
⊥ to c-axis
|| to c-axis
Specific Heat Capacity, J/(kg * °C)
0.7610 x 103
Thermal Stability, °C
Melting Point, °C
in water, gram/100 cm3
98 x 1010
Ref. Index vs. Wavelength λ
Refractive Index no
Refractive Index ne
Internal Transmittance Ti (λ) vs. Wavelength λ
Application of sapphire component.
Widely used in infrared and far-infrared military equipment, such as: used in night vision infrared and far-infrared sights, night vision cameras and other instruments and satellites, space technology instruments and meters, as well as windows for high-power lasers, various Optical prisms, optical windows, UV and IR windows and lenses, and observation ports for low-temperature experiments are fully used in high-precision instruments and meters for navigation, aerospace, and aviation.
Sapphire window/ lens
High precision grade
<3 arc min
<30 arc sec
<5 arc sec