Crystal Structure

Crystalline rhombihedral

Density

2.7 g/cm³

Mohs Hardness   

3

Hygroscopic Susceptibility

Low

 Transparency Range 

350nm ~ 2300nm 

Thermal Expansion Coefficients

aa=24.39x10^-6/K

ac=5.68x10^-6/K       

Crystal Class

Negative uniaxial with no=na=nb, ne=nc

Refractive Index

Birefringence (Δn=ne-no)

Walk-Off Angle at 45 deg(ρ)

no=1.6557, ne=1.4852, Δn = -0.1705, ρ=6.32 @633nm

no=1.6381, ne=1.4783, Δn = -0.1598, ρ=6.20 @1300nm

Sellmeier Equations (λ in um)

no²=2.69705+0.0192064/( λ²-0.01820)-0.0151624λ²

ne²=2.18438+0.0087309/( λ²-0.01018)-0.0024411λ²

Dimension Tolerance

±0.1mm

Optical Axis Orientation

±0.5deg 

Wavefront Distortion

<λ/2@633nm

Surface Flatness

<λ/4@633nm

Surface Quality

20/10 Scratch and Dig

Parallelism

<15 arc seconds

Perpendicularity

<10 arc minutes    

Clear Aperture

>90%

AR-Coating

Upon Request