A review is made of developments in wavelength measurement practice over the last 5 years. The rapid development of single-frequency tunable dye lasers has led to a requirement for quick and easy wavelength measurement at accuracies of 1 part in 106 or better. This has stimulated the development of moving-carriage interferometers and of methods of image sensing with detector arrays or vidicon tubes. There has also been progress in the attainment of very high accuracy in wavelength comparisons of stabilized lasers, now nearly matching the laser reproducibilities of a few parts in 1011. The limitations to accuracy seem to be predominantly the defects of optical surfaces and uncertainties arising from diffraction effects.

Laser wavelength measurements

Optical wavelength ratios have been measured in the range from 576 to 633 nm using a two-channel compensated field Mich- elson-type interferometer. Reference sources were provided by laser oscillators locked on the frequencies of hyperfine components of well known molecular iodine lines. The determination of the interference order in the wavelength comparisons has been achieved at a better than lo-'' relative accuracy level, according to the method of Juncar and Pinard (9). Linear deviation of the apparatus from chromaticity has also been experimentally observed and compensated, using the two previously tabulated values of the reference optical frequencies of two iodine lines.

https://ieeexplore.ieee.org/iel5/19/2790/01032915.pdf

Measurements of optical wavelength ratios using a compensated field sigmameter

We describe some properties of the two beam interferometer that we have built at the "Institut Nationalde Metrologie" for wavelength comparison. We describe particularly the phase shifts between visible wave-lengths at zero path difference.IntroductionThe National Institute of Metrology of the National Conservatory of Arts and Trades is the primary lab-oratory of the National Bureau of Metrology for lengths. It is thus responsible at the national level forthe comparison of measurements of length to the primary standard, that is, to the wavelength of the orangeradiation of krypton 86. To this end we built a two-wave interferometer of the Michelson type, workingin a secondary vacuum to eliminate any index correction. The separating plates are in Brewsterian incidenceto avoid any parasitical interference capable of dephasing the fringes. a a A Fig. 1. General view of the interferometer in its airtight case. The light beams enter and leave by theports at right. At left is the oil diffusion pump and its vacuum reservoir; the primary pump is under the

Comparison Of Wavelengths To The Primary Standard At The French National Institute Of Metrology

We have built at the Institut National de Metrologie (INM) a two beam interferometer, of Michelson type, for optical wave-length comparison. It is in vacuum and the separating plate works at Brewster’s angle. Its main quality is to give a flat field of interference at a path difference chosen for measurements (temporarily 250 mm), hence providing a large flux. The standard line of krypton provides a signal-to-noise ratio which allows us to work with a continuous scanning of path difference and a time constant less than 10−1 second.

P. Bouchareine

Papers

A Field Compensated Interferometer for Wavelength Comparison