We used a tunable cw dye laser to observe Doppler-free two-photon transitions to alkali-atom Rydberg levels. Real-time signals were obtained in an ionization cell of appropriate construction. The two-photon transition wavelengths to rubidium s levels were measured up to n = 50 with better than 1 × 10-7 absolute accuracy and can be represented to within the experimental precision by a simple function of the principal quantum number, Other related transitions and future possibilities are considered.
© 1978 Optical Society of America
S. A. Lee, J. Helmcke, J. L. Hall, and B. P. Stoicheff, "Doppler-free two-photon transitions to Rydberg levels: convenient, useful, and precise reference wavelengths for dye lasers," Opt. Lett. 3, 141-143 (1978)