MINIATURE ATOMIC FREQUENCY STANDARD DESIGN STUDY

THE PROPOSED EFFORT ADDRESSES THE NEED FOR A MINIATURIZED ATOMIC FREQUENCY STANDARD HAVING GREATLY IMPROVED STABILITY OVER PRESENT AVAILABLE DEVICES. PRECISE AND ACCURATE TIME/FREQUENCY STANDARDS ARE BASED ON ATOMIC RESONANCE EFFECTS. PORTABLE FREQUENCY STANDARDS EMPLOY RUBIDIUM, CONTAINED IN A RESONANCE CELL OR CESIUM, AS A BEAM OF ATOMS. OPTICALLY PUMPED RUDIDIUM CELL DEVICES ARE CLASSED AS SECONDARY STANDARDS DUE TO LONG TERM FREQUENCY UNCERTAINTIES, BUT ARE SUFFICIENTLY ACCURATE FOR A WIDE VARIETY OF COMMUNICATIONS AND NAVIGATION NEEDS. MORE STRINGENT REQUIREMENTS OF FIELD-DEPLOYED AUTONOMOUS TIME/FREQUENCY STANDARDS ARE REQUIRING INCREASED STABILITY IN THESE DEVICES, WITH NO COMPROMISE IN SIZE AND POWER CONSUMPTION, ALTHOUGH SOME COMPROMISE IN ACCURACY MAY BE TOLERATED. THE CRITIAL PARAMETER RELEVANT TO FREQUENCY STABILITY IS SIGNAL-TO-NOISE. IMPROVEMENT OF AN ORDER OF MAGNITUDE CAN COME FROM IMPROVED OPTICAL PUMPING SOURCES, LASERS OR OTHER, WHICH REDUCE THE NOISE ASSOCIATED WITH EXCESS BACKGROUND SIGNAL. IN THE REALM OF ATOM BEAM DEVICES, INCREASED S/N CAN COME FROM INCREASED ATOM FLUX AND IMPROVED STATE SELECTION EFFICIENCY.