Abstract: A robust method of stabilizing a diode laser frequency to an atomic transition is provided. The method employs Zeeman shift to generate an anti-symmetric signal about a Doppler-broadened atomic resonance, and, therefore, offers a large recapture range as well as high stability. The frequency of a 780 nm diode laser, stabilized to such a signal in Rb, drifts less than 0.5 MHz.sub.pk-pk (one part in 10.sup.9) in thirty-eight hours. This tunable frequency lock may be inexpensively constructed, requires little laser power, rarely loses lock, and may be extended to other wavelengths by using different atomic species.

Abstract: This invention provides an inexpensive, sensitive sensor to measure target position, velocity and vibration based on optical feedback-induced fluctuations in the operating frequency of a diode laser. The sensor comprises a diode laser, an optical frequency discriminator to measure the laser operating frequency, and an electronic signal analyzer to obtain the modulation frequency of the laser operating frequency. This invention further includes two calibration mechanisms for vibration amplitude measurement. In a first calibration mechanism the diode laser is mounted on a laser vibrator, which vibrates the laser relative to the target. In a second calibration mechanism a frequency modulator is coupled to the diode laser to modulate the operating frequency.