a -BBO Crystals
BaB2O 4 of high temperature phase is an excellent birefringent crystal; it is characterized by large birefringent coefficient and wide transmission window from 189nm to 3500nm. It is particularly suitable to make the high power UV polarizer, due to its unique UV transparency and good mechanical properties. |
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The physical, chemical, thermal and optical properties of a -BBO crystals are similar to those of b -BBO, for instant high optical homogeneity(better than 1x10-6/cm), extremely low absorption in the UV to IR range (<0.5% from 300-2300nm), low hygroscopic susceptibility, high damage threshold. However, the nonlinear optical properties of a -BBO is vanished due to the centric symmetry with its crystal structure.
| Physical and Optical Properties |
| Transparency Range |
189-3500nm |
| Density |
3.85g/cm3 |
| Therm-Optic Coefficients |
dn o / dT = -9.3 X 10 -6 / °C
dn e / dT = -16.6.3 X 10 -6 / °C |
| Optical Homogeneity |
Δn ≈ 10-6/cm |
| Damage Threshold |
1 GW/cm2 at 1064nm500 MW/com2 at 532nm |
| Hygroscopic Susceptibility |
Low |
Thermal Expansion Coefficients
(25°C--900°C) |
a a = 4 X 10 -6 / K
a c = 4 X 10 -6 / K |
| Linear Absorption Coefficients |
a<0.005cm -1 from 300nm to 2300nm |
Refractive Indices, Birefringence
(Δn=ne-no) and Walk-Off Angle at 45°C(ρ) |
ne=1.58462, no=1.65790, Δn=-0.073282; ρ=-4.9532o at 1064nm |
| ne=1.60206, no=1.67755, Δn=-0.075491; ρ=-5.0407o at 532nm |
| ne=1.67190, no=1.76171, Δn=-0.089805; ρ=-5.6926o at 266nm |
Specifications of a-BBO Components
Dimension tolerance |
±0.05 mm |
| Wedge Angle tolerance |
0.1° |
Surface Quality |
20/10 Scratch and Dig |
| Optical Axis Orientation |
+/-0.5° |
Parallelism |
<15 arc sec |
| Perpendicularity |
<10 arc min |
Flatness |
l/4 @ 632.8 nm |
Transmission Wavefront Distortion |
< l/4 @632.8 nm |
AR-coating |
R<0.3% available upon request |
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