OSCILLATION MEASURING METHOD BY HOLOGRAPHY

摘要

PURPOSE:To measure various pieces of information which could not be obtained before securely by exciting a body to be tested bynthe percussion of a hammer and emitting pulse laser light before and after the generation of impulsive force, and thus obtaining a hologram. CONSTITUTION:When a switch 121 is turned off, a hammer 110 excites a bar 117 by percussion. The rotary movement start signal of the hammer 110 is detected by a pulse fall detector 124 and applied to a double pulse laser device 126 through a delay circuit 125. Double pulse light is split by a beam splitter 129 into two pieces of liminous flux; one piece of luminous flux is used as reference light to expose a photographic dry plate 135 through a plane mirror 130, concave lens 131, collimator lens 132, optical attenuator 133, and plane mirror 134. The other piece of luminous flux is used as object illumination light to illuminate the internal combustion engine crank case 100 to be tested through a concave lens 137. The photographic dry plate 135 is exposed to light when the 100 to be tested is at a still and 50musec after being excited together with the reference light.