ABSTRACT
Lasers are widely used in current physics research because of the narrow range of wavelengths emitted by the laser, the high intensity, the high degree of collimation, and the long coherence length. Diode lasers are available in standard and frequency-stabilized versions. The standard versions are much less expensive than gas lasers. The linewidth is a few nm, with correspondingly short coherence length. The central wavelength can vary by a few nm between nominally identical units and depends somewhat on room temperature. Tables and breadboards have a high ratio of stiffness to mass, so that if there are vibrations, everything moves together as much as possible, resulting in little relative motion. The most common method of mounting optics is the post/postholder system. The posts and postholders are each available in a wide range of heights.
