CHARM – Coherence-Advanced Regulation Method
- Long-term measurement of wavelength (top trace) and fringe visibility contrast (bottom trace) of a BlueMode laser, with and without CHARM coherence stabilization.
- Continuous single-frequency operation
- Mode hops and incoherent emission intervals are eliminated
- Excellent long-term wavelength stability
- Push-button functionality
- Can be integrated in all BlueMode / GreenMode / RedMode lasers
Varying ambient conditions – temperature, air pressure and humidity levels – affect the performance of external-cavity diode lasers. Consequences are mode hops and occasional incoherent, “multi-mode” emission intervals.
TOPTICA’s unique CHARM technology (Coherence-advanced regulation method) provides an active stabilization of the laser’s coherence. Designed for the BlueMode / RedMode laser family, this scheme ensures continuous single-frequency operation – and thus excellent long-term stability of the lasing wavelength and output power.
The feedback loop is based on a proprietary FPGA regulator (“CharmControl”), which is part of the SYS DC 110 driver electronics. For applications requiring multiple wavelengths, one CharmControl unit can serve two BlueMode / RedMode lasers.
In holography or interferometry, CHARM prevents measurements becoming spoiled by sudden step changes of the laser’s power or frequency. In precision metrology, e.g. in semicon inspection tasks, the technique ensures reliable 24/7 operation of the BlueMode or RedMode laser source.
Upgrades of existing BlueMode lasers are possible and recommended.
| CHARM | COOL | FINE | SKILL | |
|---|---|---|---|---|
| BlueMode | x | |||
| iBeam smart | x | x | ||
| iBeam smart PT | x (DC) | x | x | |
| iChrome MLE | x (AC) | x | x |
