Experimental investigations of an equidistant mode distribution and of intermode beat stabilisation via the discharge current in an He — Ne/Ne laser with full self-mode-locking

An experimental investigation was made of the extent to which the mode distribution was equidistant in an He — Ne laser with a neon absorption cell and full self-mode-locking. A method was developed for stabilisation of the intermode frequency when this laser was self-mode-locked. This was done by phase locking to the frequency of an external oscillator via the discharge current. The stability of the pulse repetition (intermode) frequency was governed by stability of the frequency of an external rf standard. An analysis was made of the feasibility of using lasers with self-mode-locking stabilised at the intermode frequency as secondary standards of length utilising a Raman oscillator.