International Intercomparison of Iodine-Stabilized Helium-Neon Lasers at 633 nm Involving Ten Standards Laboratories

Abstract

An intercomparison has been made of the frequencies of He-Ne lasers stabilized using intracavity saturated absorption in '2712 at 633 nm. Lasers at ten standards laboratories (PEL (New Zealand), NRC (Canada), NBS (USA), NPL (UK), PTB (FRG), NPL (India), NIM (China), NRLM (Japan), KSRI (South Korea), and NML (Australia)) were each compared in turn with a portable laser from PEL during March to May 1984.The optical frequencies of all participating lasers exhibited a standard deviation of 23 kHz (5 parts in 10") with a range of k 40 kHz. This standard deviation is a factor of seven smaller than the standard deviation of the absolute value recommended for the optical frequency of these lasers. If allowance is made for one iodine cell believed to be contaminated, the standard deviation is reduced to 18 kHz. Power-shift coefficients were measured, and ranged from + 1.4 kHz/mW to -6 kHz/mW, referred to intracavity power.It is concluded from the measured frequency offsets and power shifts that the best frequency reproducibility amongst different designs of laser is likely to be obtained at low levels of intracavity beam power ( 5 -10 mW). The frequency reproducibility was not improved by extrapolating to zero power.

Iodine‐stabilized He‐Ne laser at λ=633 nm: design and international comparison

“…A regular verification of laser performance for reliable applications is made through international comparisons. 4,5 The main objective of such a comparison is to verify the performance of each participating laser as a frequency standard while operating properly under the specifications of the just-mentioned recommendation. Moreover, it is important to assess the sensitivity of the frequency of each laser to the factors known to cause changes of frequency.…”

Realizing traceability to the SI in dimensional metrology: today and in the future

“…International comparison of the frequency of iodine stabilized He-Ne lasers[6] Figure 3 is an attempt to illustrate current limits of uncertainty in interferometry under various conditions. The accuracy limits of interferometers for short measurement length are given by the accuracy of interpolation resulting in a constant absolute measurement uncertainty.…”