A simple extended cavity diode laser for spectroscopy around 640 nm

We report on an extended cavity diode laser for operation near 640 nm. The laser is continuously tunable in 10 GHz ranges with a maximum output power of 3 mW. The laser system has been constructed using off-the-shelf optoelectronic components and easily machinable mechanical parts. The constructed system has been used to study the saturated absorption of the closed 1s5–2p9 neon transition in a radio-frequency discharge that can be maintained at neon pressures down to 10-2 Pa.