We demonstrate how to construct a simple single-frequency extended cavity d
iode laser (ECDL) for the undergraduate laboratory using mainly standard op
to-mechanical components. This ECDL is operated with both 635 and 670 nm la
ser diodes. We present three experiments that can be performed using this E
CDL, namely spectroscopic studies of iodine, second harmonic generation, an
d an optical heterodyne experiment using the ECDL with a helium-neon laser.
(C) 2000 American Association of Physics Teachers.