Application of diode lasers as a spectroscopic tool at 670 nm

For optical experiments at the resonance wavelength of lithium atoms at 670 nm an external cavity diode laser was set up. The cavity consisted of the diode, a collimating lens and a diffraction grating used in Littrow geometry. At an optical length of 20 mm a continuously tunable range of 56 GHz was obtained using a diode with an anti-reflection coating on the output facet. 30 GHz were reached using a commercial diode as is. Laser induced fluorescence experiments on an atomic beam demonstrate the spectroscopic usability and put an upper limit of 25 MHz on the laser linewidth.