Time-resolved observations show that the near field and far field patterns of an active Q-switched ruby laser remain almost constant for the duration of the output pulse. This is in marked contrast to the reported behavior of a passive Q-switched laser.
W. E. K. Gibbs and R. E. Whitcher, "Time-Resolved Beam Structure of an Active Q-Switched Ruby Laser," Appl. Opt. 6, 1957-1959 (1967)