Patent ID: 8264284

Claim:
An atomic frequency acquisition device comprising: a gas cell filled with an atomic gas having first and second energy transitions allowing coherent population trapping, said first and second energy transitions corresponding to first and second transition frequencies; a laser light source with a laser cavity emitting a laser beam which enters the gas cell and excites the first energy transition of the atomic gas; a local oscillator adapted to generate an oscillator frequency in a frequency range including half of the second transition frequency of the atomic gas; a modulator modulating said laser light source so as to emit laser radiation modulated with the oscillator frequency; an optical reflector arranged to reflect the laser beam after passage through the atomic gas so as to re-enter the laser cavity, said re-entered laser beam causing a self-mixing effect in the laser cavity, resulting in beat frequencies in an intensity of the emitted laser radiation; a photodetector arranged to provide an output signal comprising said beat frequencies; and a control unit connected to the photodetector and the local oscillator and controlling the local oscillator so as to periodically vary the oscillation frequency between two frequency margins based on the beat frequencies, the two frequency margins being adapted in such a way that a maximum beat frequency in the output signal of the photodetector is within the two frequency margins.