Simple rubidium stabilized diode laser for gauge block interferometer

摘要

A simple rubidium stabilized diode laser has been developed for a gauge block interferometer. The laser light source is a commercially available external-cavity tunable diode laser (New Focus Inc.). Laser frequency stabilization is realized by the third-harmonic technique, where a fast frequency modulation (10 kHz) is applied on the current. The absolute laser frequency was calibrated by an absolute optical frequency measurement system using a femtosecond mode-locked laser. The relative uncertainty of the laser frequency reached 4.3 * 10~(-10) for an averaging time of 0.01 s. The phase error in the interferometeric measurement due to the optical frequency modulation is theoretically indicated to be small enough to measure long gauge blocks of up to 1000 mm. Long gauge block measurement of up to 1000 mm was successfully demonstrated using the developed rubidium stabilized diode laser and the I_2-stabilized offset locked He-Ne laser (633 nm).