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
|
| 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 |
|
