Nondestructive Holographic Techniques for Structures Inspection

An investigation of various problems to be encountered in technically difficult physical environments as a result of ambient lightning, vibration and suspended aerosols is reported. Successful pulsed holographic experiments on composite rotor blades are also reported. An evaluation of the effects that various surface finishes have on the holographic construction process which indicated that surface roughnesses from 4 microinches (very smooth) to 1000 microinches are amenable to the method. The development of the theory required to relate holographic records to the strain patterns and areas of maximum strain present on the large structures, together with experimental studies exhibiting good correlation between the holographically calculated strain and that measured with gages.