Inconsistent output power variation between the laser beams from both sides of a He-Ne laser is examined, and it is found that the variation is a result of the superposition of two different phenomena:
One is a lazge-amplitude periodic variation produced by the change of the laser mirror transmittance; this variation can be avoided by making wedges of more than four minutes of arc in both sides of the mirror substrates.
The other is a small-amplitude periodic variation related to the longitudinal mode changes of the laser, although it is not exactly clear how it is caused. This variation can also be avoided by making wedges in both sides of the mirror substrates.
View full abstract