He-Ne lasers meet metrology challenges at PTB

LASOS developed custom He-Ne lasers for Germany’s National Metrology Institute, PTB.

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Figure. PTB measuring station for laser wavelength calibration by three iodine stabilized He-Ne gas lasers.

In recent years, the laser diode has replaced the Helium-Neon (He-Ne) gas laser in many high-volume applications such as barcode scanning, marking, and aligning. Yet as the He-Ne laser has ceased to be a high-volume product, it has become the preferred laser for specific high-value applications, including precision measuring applications in interferometers and spectrometers. The applications require rigorous mode and frequency stability--as well as resistance to magnetic fields.

LASOS (Jena, Germany) says it has responded to this changing market by investing in a new He-Ne laser manufacturing facility to produce both customized and standardized products. The company recently developed a custom He-Ne laser tube for Germany’s National Metrology Institute, the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig. The tube--LGR 7660 BF01—is now part of the ultra-precise interferometers of PTB.

PTB notes that the design of this laser dates from the 1970s and its reliability and stability have been optimized to current standards. The lasers contain an iodine cell of 10 cm length and a special He-Ne tube with Brewster windows approximately 25 cm long. The laser cavity is 37 cm long; the Zerodur rods maintain the distance between the mirrors.

Related article: Interferometry: Time in a fiber

Figure. Iodine stabilized lasers at PTB. The cavity mirror mounts are kept apart by three Zerodur rods. The iodine cell is seen in the foreground, the LASOS laser tube at the rear.

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