抄録
Laser diodes (LDs) have many advantages such as compact size, high power, and long lifetime compared with gas lasers. Moreover, LDs offer direct frequency modulation by modulating an injection current and large frequency tuning. Therefore, LDs are candidates of the light sources for the precise displacement measuring interferometers. However, the frequency stability of LDs is typically lower than He-Ne laser and hence the accuracy of displacement measurements can be decreased. The frequency stability of LDs can be improved by locking the LD frequency to the atomic or molecule absorption lines. Iodine molecule (I2) offers absorption lines that can be used as frequency references. In this paper, we propose the use sinusoidal frequency modulation on an LD to achieve both the frequency stabilization of the LD and a displacement measurement by a homodyne interferometer. A central frequency of the LD is locked to an I2 saturated absorption line near the wavelength of 633 nm. The I2 frequency stabilized LD is then applied to a Michelson interferometer. In this experiment, the displacement measurement at a resolution of nanometer can be achieved.
