We describe the construction and operation of a simple, compact, and cost effective Michelson wavemeter with picometer accuracy. The low cost of the device means that it can form the basis of an undergraduate laboratory experiment, yet it is sufficiently reliable and accurate that it has become an important tool in our research laboratory, where it is regularly used to tune lasers to atomic transitions. The usefulness and accuracy of the wavemeter is demonstrated by tuning two separate extended cavity diode lasers to achieve two-step excitation of the Rb 52D state, observed by detecting 420 nm blue fluorescence from the 52D→62P→52S decay path.

A reliable, compact, and low-cost Michelson wavemeter for laser wavelength measurement

172Yb+ ions in an rf trap have been laser cooled for the first time by driving the 2
S
1/2–2
P
1/2 transition at 369.5 nm. It was necessary to irradiate the ions with 2.438 μm infra-red radiation to depopulate the metastable 2
D
3/2 state. An upper limit on ion energies was determined by observing the size of the trapped cloud and corresponds to a temperature below 2 K. Cooled ion lineshapes were compared with simulations and coherence nulls were observed in the infra-red frequency scans.

Laser cooling of trapped Yb

Inverse Raman spectrum of the ν1-fundamental of CF4☆

A simple fringe-counting interferometer for laser wavelength measurement is described. Measured values of the wavelengths of several helium-neon, argon and krypton laser lines, stabilised by saturated absorption in iodine vapour, are presented, with uncertainties of two parts in 108 (99% confidence).

https://iopscience.iop.org/article/10.1088/0022-3735/13/2/016/pdf

A digital interferometer for wavelength measurement

A tuneable dye laser saturated absorption measurement of three of the fine-structure components of the Balmer alpha line of atomic hydrogen in a gas discharge yields a value of 10, 973, 731.513(85) m-1 for the Rydberg constant. The number in parenthesis is the uncertainty in the last digit quoted. It represents a standard deviation which is obtained by combining the random (0.021 m-1) and systematic (0.082 m-1) uncertainties as the root sum of their squares.

https://iopscience.iop.org/article/10.1088/0022-3700/13/16/008/pdf

K. Morris

Papers

A simple CW laser digital wavemeter

Operation of a narrow-band CW tuneable dye-laser at 656 nm