Two new methods for real-time precision refractometry and a precise test of the hyperfine Hamiltonian via modulation transfer spectroscopy of molecular iodine at 532 nm.

摘要

wo powerful methods for precisely tracking changes in the index of refraction of air are realized. Method 1 utilizes a parallel-plate Fabry-Perot interferometer illuminated with light from a frequency-stabilized laser and exposed to ambient air. A PC processes the fringe pattern imaged onto a 1024 element CCD linear array detector. Method 2 realizes an air-wavelength-stabilized laser. A tunable laser is locked onto a transmission peak of an optical cavity which is completely exposed to ambient air. Index of refraction changes within the cavity mode volume are mapped onto the laser frequency. A beat frequency measurement against a reference laser allows a direct readout of the changes.;Output for each method is compared with Edlen's formula and deviations are noted at the few ;The hyperfine structure of several transitions in ;The modulation transfer lineshape's odd symmetry is used for laser stabilization. Allan Variance measurements of the two lasers stabilized onto hyperfine components of Iodine show fractional frequency fluctuations of