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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.

The program is an investigation of the feasibility of using holographic interferometry for the inspection of large aircraft structures in a manufacturing or maintenance environment. The second year's work comprised the following: An investigation of the effects of airborne particulates on the holographic process, a study of holographic methods suitable for the manufacturing or maintenance environment, an investigation and experimental demonstration of two new moire methods for the visualization of strain patterns, investigations of potential stress generating mechanisms, suitable for the holographic detection of cracks, in which it was experimentally demonstrated that surface waves can be generated and attenuated by cracks, and experimental demonstrations that illustrated the potential of holography, in combination with ultrasonic excitation, for solving cooling passage alignment inspection problems. (Modified author abstract)

The primary results of a research investigation to determine the feasibility of applying interferometric holography to turbine blade stress analysis are reported and may be briefly summarized as follows: (1) It has been demonstrated that the strain at the surface of a turbine blade, excited in dynamic flexure, can be calculated from interferometric holographic fringe information. (2) Interferometric holography appears to offer some promise in the detection of weaknesses, unusual wear or fatigue in turbine blades, however experimental implementation and fringe interpretation would be a somewhat time consuming process. (3) The introduction of elevated temperatures to the turbine blade stress analysis problem requires the use of pulsed holographic techniques for best results, but otherwise it appears to present no insurmountable problems. (4) Pulsed interferometric holograms of transient and cyclically excited turbine blades have been successfully and readily constructed, demonstrating that the developed pulsed laser system possesses more than sufficient pulse reproducibility, coherence and intensity for recording reflected light holograms. (Author)

A description is presented of the progress made on the research and development of an ultrasonic light scanning and active optical imaging system during the second quarterly reporting period ending 19 December 1963. As in the first quarterly report, the main body of the current report is presented in two sections: Ultrasonic Light Scanning and Active Optical Imaging System. Efforts on the ultrasonic light scanning portion of the work have been concentrated on the analytical evaluation and experimental development of a liquid deflection cell since it is this type of cell which is presently thought to be best suited for the demonstrational model of an optical imaging system. In the second section both analytical and experimental results (the former concerned with the overall system and the latter with the demonstrational model) of the continuing study of the active optical imaging system are presented. (Author)