A Dye Laser Spectrometer with an External Iodine Cell Designed for Optical Ramsey-Fringe Spectroscopy in a Ca Atomic Beam

Abstract
A novel dye laser spectrometer stabilized to a hyperfine component of molecular iodine as a frequency reference was developed for observing optical Ramsey fringes in a Ca atomic beam. The resolution of the spectrometer was less than 1 kHz and the uncertainty of the absolute frequency was within 20 kHz. By using this spectrometer, Ramsey fringes with a width of 10 kHz and a signal-to-noise ratio of 200 were obtained with an integration time of 5 ms. The frequency separation between lines of Ca (1S0-3P1) and I2. (g, 3–4, R(67)) was measured to be 191.48±0.02 MHz.