Precise measurement of hyperfine structure in the 6P1/2 state of 133Cs

We have measured hyperfine structure in the 6P(1/2) state Of Cs-133 using a frequency-stabilized diode laser and acousto-optic modulators that produce calibrated frequency offsets. We check for errors due to radiation-pressure and optical-pumping effects by repeating the measurements at different values of pump power in a saturated-absorption spectrometer. We obtain a precise value of the magnetic-dipole constant, A = 291.9135(15) MHz, representing an improvement of more than an order of magnitude.