Short exposure and biasing holography

Experiments with an ordinary laser performing a time-average are reported which approach the effect of pulsed laser holography. In the case of a vibration superposed on random motion, it is possible to record only the vibration by using an exposure time short enough to consider the motion as stationary. Because of the short exposure time, the exposure of the plate does not fall in the linear part of the transmittance-exposure curve. However, by illuminating with a bias light, the total exposure can be shifted into the linear region.