1. The Helium-Cadmium laser
Ronald Mooiweer
The Helium-Cadmium laser

2. The Helium-Cadmium laser
Outline
General Information
Excitation mechanism
Lasing transitions
Line Broadening
Applications
Research example
Tuesday, 07 April 2009
The Helium-Cadmium laser

3. The Helium-Cadmium laser
General Information
cw metal vapor laser
Lasing at and nm
Cataphoresis to distribute Cd
He leaks, Cd condenses
Operating lifetime of about 5,000 hours
Tuesday, 07 April 2009
The Helium-Cadmium laser

4. The Helium-Cadmium laser
General Information
Tube length: m
Bore: 1-2 mm
Gas pressure: 5-10 Torr He
Gas mixture: He:Cd , 100:1
Operating temperature: 300°C
Output power: mW
Mode: TEM00 or multi-mode
Tuesday, 07 April 2009
The Helium-Cadmium laser

5. The Helium-Cadmium laser
Excitation mechanism
Penning ionization
Electron excitation of Cd+
Photo ionization from He
Tuesday, 07 April 2009
The Helium-Cadmium laser

6. The Helium-Cadmium laser
Lasing transitions
325.0 and nm : UV
441.6 nm : Blue
Tuesday, 07 April 2009
The Helium-Cadmium laser

7. The Helium-Cadmium laser
Line Broadening
Isotope broadening>
Doppler broadening>
Homogeneous broadening
Tuesday, 07 April 2009
The Helium-Cadmium laser

8. The Helium-Cadmium laser
Applications
3D stereolithography
Mastering compact-disks
Creating embossed holograms
Photoluminescence analysis
Tuesday, 07 April 2009
The Helium-Cadmium laser

9. The Helium-Cadmium laser
325 nm He-Cd laser
Small peaks of green emission suggest oxygen at zinc position in lattice
The increase of oxygen pressure contriutes to the ZnO grain size and then promotes UV emission
Tuesday, 07 April 2009
The Helium-Cadmium laser