CdS and CdSe IR birefringent crystals
In the recent time increased interest of R & D sector and analytical instrumentation manufacturers to the IR spectral range is observed. Accordingly, there appear demand in polarization elements for 2 – 20 mm range made of crystals transparent in required range and having sufficient birefringence.
Uniaxial crystals of Wurtzite structure CdS and CdSe are promising materials for fabrication of polarizing prisms, beamdisplacers and waveplates for IR range.
CdSe crystal is good nonlinear material as well and can be used for wavelength conversation in the range 2 – 15 mm.
Main properties of CdS and CdSe are given below:
-
Parameter |
CdS |
CdSe |
Structure |
Wurtzite (Hexagonal) |
Wurtzite (Hexagonal) |
Density |
4.825 g/cm3 |
5.81 g/cm3 |
Young Modulus |
45 GPa |
50 GPa |
Thermal Expansion (500 K) |
a 1=6.26?10-6/K;
a 3=3.5?10-6/K |
a 1=6.26?10-6/K;
a 3=4.28?10-6/K |
Specific Heat (25 °C) |
0.47 J/gK |
0.49 J/gK |
Thermal Conductivity (25 °C) |
0.2 W/cmK |
0.04 W/cmK |
Transmission (10% level) |
0.53-15 mm |
0.75-25 mm |
Max. Transmission
( λ =2.5-15 mm) |
≥71 % |
≥ 71 % |
Absorption
( λ =10.6 mm) |
≤ 0.007 cm-1 |
≤ 0.0015 cm-1 |
Refractive Indices
no /ne for λ =0.8 mm
1.0 mm
3.39 mm
10.6 mm |
2.377/ 2.394
2.336/ 2.354
2.2747/ 2.2907
2.226/ 2.239
|
2.6448/ 2.6607
2.5502/ 2.5696
2.4562/ 2.4754
2.430/ 2.448
|
Max. sizes (dia. x length) |
Ø 40x30 mm |
Ø 40x50 mm |
|
