Optical absorption monitoring of aligned alkali atoms

Claim 1

APPARATUS FOR ALIGNING ALKALI ATOMS IN THE GROUND STATE COMPRISING: AN ABSORPTION VESSEL FOR CONTAINING SUCH ALKALI ATOMS IN A UNIDIRECTIONAL FIELD; MEANS FOR IRRADIATING THE ALKALI ATOMS WITH OPTICAL RESONANCE RADIATION THAT HAS A PROPAGATION DIRECTION COMPONENT PARALLEL TO THE UNIDIRECTIONAL MAGNETIC FIELD, SUCH RADIATION HAVING A SPECTRAL FREQUENCY SUPPLYING QUANTA OF ENERGY TO PRODUCE TRANSITIONS BETWEEN ENERGY LEVELS SO THAT THE ALKALI ATOMS MAY BE ALIGNED IN THEIR GROUND STATE; AND MEANS FOR MINIMIZING THE COLLISIONS OF ATOMS WITH THE WALLS OF THE CONTAINNG ABSORPTION VESSEL SAID MINIMIZING MEANS COMPRISING A BUFFER GAS AT A PRESSURE SUBSTANTIALLY GREATER THAN ONE MILLIMETER OF MERCURY SO THAT THE RELAXATION TIME OF THE ATOMS IS INCREASED, THEREBY MAINTAINING THE ALIGNMENT OF THE ALKALI ATOMS IN THE GROUND STATE FOR AN INCREASED PERIOD, AND MEANS FOR MEASURING THE INTENSITY OF NON-ABSORBED OPTICAL RADIATION RECEIVED FROM SAID ABSORPTION VESSEL DURING THE ALIGNMENT OF THE ALKALI ATOMS IN THE GROUND STATE.