NPL has many years of experience with laser stabilisation as part of its programme of research into optical frequency (wavelength) standards for use in interferometry. Stabilised He-Ne lasers operating at various wavelengths were developed at NPL for this purpose:

• 633 nm (red) - circularly polarised
• 543 nm (green) - linearly polarised
• 612 nm (orange) - linearly polarise
• 594 nm (yellow) - linearly polarised

All the lasers operate in a single frequency TEM₀₀ mode with output powers in the range 0.1 mW to 1 mW. The frequency stability and reproducibility of these lasers is approximately 2 parts in 10⁹, though each laser exhibits an individual characteristic frequency drift proportional to the time the laser has been switched on, of approximately 1 part in 10¹¹ per hour of use. The lasers exhibit a sufficiently long coherence length to make them suitable for interferometry. Warm-up and lock to the calibrated frequency is automatic and takes about 15 minutes. The laser control unit indicates when lock has been achieved. An acousto-optic isolator/shutter and optical fibre launcher can be incorporated as standard options in all of the lasers. All lasers can be supplied with an individual calibration performed by comparison against NPL national reference standards.

NPL-Hexagon Metrology stabilised laser

Following initial development at NPL, a licence to manufacture the lasers was granted to Hexagon Metrology of Telford, England. Hexagon Metrology now manufactures and sells the lasers under licence.

For technical details about the laser design please contact Patrick Gill at NPL. However for any commercial questions or details about the instrument as delivered to customers, please contact Hexagon Metrology directly:

Dr Philip Aldred
Hexagon Metrology
Metrology House
Halesfield 13
Telford
Shropshire
TF7 4PL
UK

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