Overview: High temperature form BBO (α-BaB2O4) is an excellent negative uni-axial birefringent crystal. It has
large birefringence coefficient and good transmission over a broad
range, from 189nm to 3500nm. Unlike ß-BBO, α-BBO is not useful for
NLO application due to the centric symmetry with its crystal
structure.
α-BBO is excellent crystal in Glan Taylor, Glan Laser and Glan
Thompson polarizer as well as walk-off beamsplitters, especially
for high power and UV polarizers. This is due to their unique UV
transparency, good mechanical properties and high damage threshold.
Union Optic manufactures many Glan polarizers and beam displacers
from high quality α-BBO crystals for UV and high power operations. General Specifications Of α-BBO: | Dimension Tolerance | ±0.1mm | | Optical Axis Orientation | ±0.5deg | | Surface Quality | 20/10 Scratch and Dig | | Clear Aperture | >90% | | Surface Flatness | <λ/4@633nm | | Wavefront Distortion | <λ/2@633nm | | Parallelism | <15 arc seconds | | Beam Deviation | <3 arc minutes | | AR Coating | Upon Request |
Physical and Optical Properties of α-BBO: | Transparency Range | 189~3500nm | | Density | 3.85g/cm3 | | Mohs Hardness | 4.5 glass like | | Optical Homogeneity | Δn≈10-6/cm | | Therm-Optic Coefficients | dno/dT= - 9.3x10-6/°C
dne/dT= - 16.6x10-6/°C | | Thermal Expansion Coefficients(25°C~900°C) | aa=4x10-6/K | | ac=36x10-6/K | | Linear Absorption Coefficients | a<0.005cm-1 from 300nm to 2300nm | | Damage Threshold | 1GW/cm2 at 1064nm, 200MW/cm2 at 532nm | Refractive Index Birefringence (Δn=ne-no) Walk-Off Angle at 45 deg(ρ) | ne=1.53797, no=1.65790, Δn= - 0.11993, ρ= - 4.9532° at 1064nm
ne=1.55345, no=1.67755, Δn= - 0.12411, ρ= - 5.0407° at 532nm
ne=1.61145, no=1.76171, Δn= - 0.15026, ρ= - 5.6926° at 266nm | | Sellmeier Equations (λ in um) | no2=2.7471+0.01878/( λ2-0.01822)-0.01354λ2
ne2=2.37153+0.01224/(λ2-0.01667)-0.01516λ2 |
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