Alexandrite
Be(Al1-xCrx)2O4
Due to properties such as laser wavelength and tunability, Alexandrite is used in a wide range of medical applications.
Alexandrite lasers emit at a wavelength of 755 nm, well within the absorption spectrum of melanin, and this makes the laser perfectly suitable for removing hair. Alexandrite lasers are also used for a variety of aesthetic dermatology procedures.
Cr concentration uniformity along each rod is achieved by using only a small portion (about 20%) of the melt, with a very uniform Cr profile being certified for each boule.
Optical Properties
Refractive index@755nm | E II a=1.7367 |
E II b=1.7421 | |
E II c=1.7346 | |
Lasing wavelength | 710 - 800 nm |
Primary diode pump band | 594 nm |
Material Properties
Cr doping level | 0.01 - 0.2% atomic |
Chemical formula | Be(Al1-xCrx)2O4 |
Molecular weight | 127.01 g/mole |
Crystal structure | Orthorombic |
Lattice constant | a=5.476 Å |
b=9.404 Å | |
c=4.427 Å | |
Melting point | 1870 °C |
Density | 3.67 gr/cm3 |
Hardness (Mohs) | 8.5 |
Thermal Properties
Thermal conductivity | 0.23 W/(cm•K) |
Linear expansion coefficient | II a=5.9 x 10-6/K |
II b=6.1 x 10-6/K | |
II c=6.7 x 10-6/K | |
Dissipative fracture limit | 35-74 W/cm |
Young modulus | 469 Gpa |
Rod Specifications
Cr Concentration | |
Concentration | Available from 0.1 to 0.2% |
Dimensional tolerance | |
Diameter | +0.00 / -0.05 mm |
Length | +0.25 / -0.00 mm |
Chamfer | |
Depth | 0.02±0.01 mm |
Angle | 45°±5° |
End Configuration | |
Parallelism | <10" |
Perpendicularity | <2' |
End angle tolerance | ±10' |
End Surface Finish | |
Flatness | < λ /10 at 633 nm |
Scratch-dig (as per MIL-I-13830A) | 10 – 5 |
Wavefront distortion | |
Per inch of rod length | < λ /2 at 633 nm |
Standard coating specification | |
Anti-reflection | <0.2% |
Traceability | |
Laser marking | Lot number on rod external surface |