  The design of a 671 nm diode laser with a mode-hop-free tuning range of 40
GHz is described. This long tuning range is achieved by simultaneously ramping
the external cavity length with the laser injection current. The external
cavity consists of a microscope cover slip mounted on piezoelectric actuators.
In such a configuration the laser output pointing remains fixed, independent of
its frequency. Using a diode with an output power of 5-7 mW, the laser
linewidth was found to be smaller than 30 MHz. This cover slip cavity and
feedforward laser current control system is simple, economical, robust, and
easy to use for spectroscopy, as we demonstrate with lithium vapor and lithium
atom beam experiments.
