Holographic recording instrument for structural integrity verification and other applications

Claim 1

A holographic recording instrument comprising: holographic recording means including a pulsed laser for recording on the same holographic recording medium two successive holograms of a structure of interest by operating the laser to emit two short laser pulses in rapid succession, and a shutter for controlling light passage to said recording medium, an impulser including a plunger and means for driving said plunger into impact with said structure for impulsively loading said structure to generate stress waves which propagate through and create varying stress conditions in the structure, and means for operating said shutter, loading means, and laser in timed relation in such a way that said laser pulses occur while said shutter is open and in different timed relation to the propagation of said stress waves through the structure to record on said recording medium a first hologram of said structure while the latter is in one stress condition and a second hologram of said structure while the latter is in another stress condition, said operating means comprising means for actuating said shutter to momentarily open the shutter, means for sensing and actuating said plunger driving means in response to a selected condition of said shutter, and means for sensing and actuating said laser in response to movement of said plunger by said plunger driving means.