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Sapphire (Al2O3) Windows

Sapphire is the aluminum oxide (Al2O3) single crystal
and one of the hardest materials. It has a good transmission from the visible to near IR spectrum and has high chemical resistance and thermal stability. It is often used as optical windows in a harsh environment. Recently, sapphire windows are widely used for broadband continuum generation pumped by femtosecond lasers.  

                                                                                             Continnum pumed by 100fs,  800nm

Shapes and Geometries


Round Parallel Windows


Square Parallel Windows

 * Other shapes and geometries are routinely fabricated by Newlight Photonics.
     Please contact us for your specific needs.

Basic Properties of Sapphire Crystals

Transparency Range: 180 - 4500 nm

material-sa.GIF (11133 bytes)

Transmission Curve

Crystal Symmetry: Hexagonal
Density:  3.98 g/cm3
Lattice Constants: a=b=4.758A, c=12.991A
Thermo-Optic Coefficients:
dn/dT= 1.2 x 10-6 /oC
Optical Homogeneity: Δn < 10-6/cm
Mohs Hardness:  9.0
Thermal Conductivity: 52 W/m/K
Thermal Expansion Coefficients: α = 8.4 x 10-6/K

Sellmeier equations: (λ in µm) :
no2=1+ 1.43135 λ2/( λ2 - 0.00528  ) + 0.65055 λ2/(λ2- 0.01424)+ 5.34140 λ2 /( λ2-325.01800 )  
ne2=1+ 1.50398 λ2/( λ2 -  0.00548 ) + 0.55069λ2/( λ2-0.01480 )+ 6.59274λ2/( λ2-402.89500 )
Wavelength(nm) no ne Birefringence
(Δn=ne -no)		 Walk-off Angle
 at 45°
1064 1.7545 1.7467 -0.0275 0.257
800 1.7602 1.7522 -0.0278 0.258
532 1.7717 1.7636 -0.0288 0.263
355 1.7960 1.7873 -0.0310 0.276
266 1.8331 1.8236 -0.0346 0.296

Specifications of Sapphire Windows

Orientation

c- or a- or randomly cut as specified
Dimension Tolerance ±0.1mm
Clear Aperture > 85%

Surface Quality

20/10 Scratch and Dig

Perpendicularity

<10"
Parallelism <3"

Flatness

λ/2 @ 632.8 nm

Transmission Wavefront Distortion

<λ/4 @632.8 nm

Bevel <0.25mm X 45°

 

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