Design and experiments of a 629nm He-Ne laser with an internal Fabry-Perot etalon

A wavelength selection method by a Fabry-Perot etalon in cavity is reported, helping weak line in laser cavity emitting. Comparing with other wavelength selection methods, this method can provide better resolution of lines, more output power and need shorter length of cavity. A series of experiments are done to test the output properties of the 629nm He-Ne Laser. The wavelength selection method in He-Ne Laser by internal F-P etalon could choose the needed one from two nearby lines no matter how close they are. That makes it possible to select wavelength especially for the nearby lines with gain of sharp contrast in other Lasers.