10 Jan 2007 The torus is a high-specification, single-frequency DPSS laser. Using intelligent electronics, the torus continually tracks the longitudinal mode position and ensures there is no mode-hop. The torus is available at 532nm, with power from 50 to 400mW Beam Quality
Due to its pure spectral quality, it follows that the spatial quality is also very pure. The typical M2 value of the torus beam is <1.1 resulting in a near perfect and near diffraction-limited beam.
Single Frequency
The patented cavity of the torus ensures that it operates inherently single-frequency. The photons resonant in the cavity form a travelling wave, removing mode competition and resulting in the laser operating on just one mode.
Active Feedback
Despite the torus operating inherently singlemode, mode-drift and eventual mode-hop would occur if the cavity was allowed to change length. Using four PID temperature controllers, the effects temperature change on the laser are minimised. Addition to these, the digital power supply receives a signal from the laser which tells it the exact position of the mode many times a second. The power supply feeds back a control signal which maintains the position of the mode. This active feed-back removes the risk of mode-hop and leads to a stable output.
The spectrum above shows a single shot of a torus beam using a 200 MHz free-spectral range etalon with a finesse of 50. The five etalon peaks are clear and there are no other secondary modes visible. The resolution of the etalon is 4 MHz and the bandwidth of the torus is <1 MHz.
For more information please see our technical specifications. |
