Alpha-BBO
High temperature phase of BaB 2 O 4 is an excellent birefringent crystal; it is characterized by large birefringent coefficient and wide transmission window from 189nm to 3500nm, particularly it is suitable to make the high power UV polarizer, due to its unique UV transparency and good mechanical properties.
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
Specifications:
| Diameter: | Max 50m |
| Length: | Max 35mm |
| Surface Quality: | better than 20/10 scratch/dig |
| Beam Deviation: | < 3 arc min |
| Optical Axis Orientation: | +/-0.2deg |
| Flatness: | < l/4 @632.8nm |
| Wavefront Distortion: | < l/2 @632.8nm |
| Coating: | Coating upon Request |
Properties:
| Transmitting range | 189nm~3500nm |
| Density | 3.85g/cm3 |
| Therm-Optic Coefficients | dno/dT=-9.3 x 10-6/ °C dno/dT=-16.6x10-6/ °C |
| Optical Homogeneity | Dn»10-6/cm |
| Damage Threshold | 1GW/cm2 at 1064nm 500MW/cm2 at 532nm |
| Hygroscopic Susceptibility | Low |
| Thermal Expansion Coefficients | aa=4x10-6 |
| (25 °C - 900 °C) | aa=4x10-6 |
| Linear Absorption Coefficients | a<0.005cm-1 from 300nm to 2300nm |
| Refractive Indices, Birefringence(Dn=ne-no) and wal-off Angle at 45 °C(r) |
ne=1.5379,no=1.65790,Dn=-0.073282;r=-4.9532° at 1064nm ne=1.5534,no=1.67755,Dn=-0.075491;r=-5.0407° at 532nm ne=1.6114,no=1.76171,Dn=-0.089805;r=-5.6926° at 266nm |
| Sellmeier equation(l in mm) | no2=2.7471+0.01878/(l2-0.01822)-0.01354l2 ne2=2.3753+0.01224/(l2-0.01667)-0.01516l2 |