Acoustical Holography : Volume 2

This volume presents the proceedings of the Second International Sym­ posium on Acoustical Holography, which was held at the Douglas Advanced Research Laboratories on 6 and 7 March 1969, fifteen months after the first symposium. Space was limited to about 110 seats, with representatives from nine countries attending. These countries included Canada, England, France, Japan, Mexico, Scotland, Sweden, Switzerland, and the United States. The symposium consisted of 21 formal papers. The twenty second, by Dr. U. Fehr, was not read, but is included in these proceedings. The manu­ script of the interesting paper on acoustic propagation in a turbulent medium which was read by Dr. O. K. Mawardi was not received in time for publication in these proceedings, and we look forward to its publication perhaps at a later date in the open literature. In addition to the formal papers there were three informal presentations at the end of the meeting which were given by Dr. A. Lohmann, by L. A. Cram and K. O. Rossiter, and by T. S. Graham, which are also included in these proceedings. At the end of the formal presentations Dr. Lewis Larmore summarized the symposium and discussed some of the highlights. For the symposium summary and a summary of these proceedings the reader is referred to Chapter 1.

1 Symposium Summary.- 2 Progress in Acoustical Holography.- Liquid-Surface Deformation.- A Unified Theory of Holography.- New Developments in Scanned or Sampled Holograms.- Reciprocal Holograms.- Simultaneous Scanning with Source and Detector.- Bragg Diffraction, or Direct Interaction of Light and Sound.- Conclusion.- References.- 3 On The Theory of Acoustical Imaging.- The Ray Theory of Acoustics.- Pseudorays.- Characteristics of Pseudorays.- The Step Response.- Asymptotic Solution of Wave Equation.- Propagation in Dispersive Media.- The Equation of the Pseudoray.- Transfer Matrix for Pseudorays.- References.- 4 Eikonal Theory of Bragg-Diffraction Imaging.- The Eikonal Equation for the Scattered Field.- Application to Two-Dimensional Imaging.- References.- 5 Liquid-Crystal Detectors.- Sensitivity.- Types of Detectors.- Summary.- References.- 6 Large-Aperture Acoustical Image Converters.- The Continuous-Wave Sokolov Image Converter.- Desirability of Increased Aperture.- Limitations on Increased Apertures in the AIC.- Means of Achieving Increased Aperture.- Conclusion.- References.- 7 Temporal Reference Acoustical Holography.- Theory of Temporal Reference Holography.- Recording the Temporal Reference Hologram.- Reconstructing the Temporal Reference Hologram.- The Reconstructing Wavefront U0.- Reconstructing with a Different Radiation and Wavelength.- Temporal Reference Acoustical Hologram Recorded with a Sokolov Ultrasound Camera.- Proposed Methods for Optical Recording of Temporal Reference Acoustical Holograms.- General Description of Double-Exposure Subfringe Inter-ferometric Holography.- Double-Pulsed Laser System.- Swept-Beam CW Laser System.- Discussion.- References.- 8 Acoustical Imaging with Linear Transducer Arrays.- Aberrations.- Conic Aberration.- Velocity Aberration.- Comparison with Other Systems.- Digital Simulation.- Diffraction Pattern in Image of a Point.- Triangle Images.- References.- 9 Acoustical Holography by Optically Sampling a Sound Field in Bulk.- References.- 10 Focusing and Scanning of Acoustic Waves in Solids.- Comparison of Contrast Sensitivity for the Scanned and Simultaneous Imaging Techniques.- Magnetoelastic Scanning and Focusing.- Electroacoustical Scanning and Focusing.- Optically Controlled Acoustic-Beam Scanning.- References.- 11 The Application of Holographic Concepts to Sonar.- Present Practice in Sonar Processing.- Some Fundamental Considerations in Sonar Viewing and Processing Systems.- Angular Resolution.- CW Ranging by Focusing or Parallactic Effects.- Ranging by Echo Timing.- Number of Resolvable Elements and Field of View.- Image Quality.- Optical Configurations for Sonar Processing.- CW Holographic Processor.- Multichannel Correlator.- Beam-Former-Correlator.- Two-Angle Beam-Former-Correlator.- Spectrum Analyzer.- Hybrid System : Multichannel Correlator with Holographic Output.- Additional Optical Engineering Considerations.- Storage Medium.- Input and Output Interfaces.- Summary.- References.- 12 An Underwater Viewing System Using Sound Holography.- Performance Requirements.- General Considerations.- Receiving Array.- Real-Time Display System.- Conclusion.- References.- 13 Computed Reconstructions from Phase-Only and Amplitude-Only Holograms.- Phase-Amplitude Hologram.- Fraunhofer Region.- Fresnel and Very-Near-Field Regions.- Phase-Only Hologram.- Fraunhofer Region.- Fresnel and Very-Near-Field Regions.- Amplitude-Only Hologram.- Fraunhofer Region.- Fresnel and Very-Near-Field Regions.- Biased Phase-Only Hologram.- Theory.- Fraunhofer Region.- Fresnel and Very-Near-Field Regions.- Summary.- References.- 14 Comments About Phase-Only Holograms.- The Problem.- The Background of the Problem.- Some Examples.- Phase-Only Holograms and Geometric Optics.- The Set of Objects Suitable for Phase-Only Holograms.- References.- 15 Computer Reconstruction of Images from Ultrasonic Holograms.- The Data-Acquisition System.- Reconstruction of the Digital Image.- Display of Digital Images.- Results.- Conclusions.- References.- 16 Acoustical Holography Experiments Using Digital Processing.- Earth Holography.- Existing Seismic Methods.- Scaling Problems.- Model Studies.- Conclusions.- 17 Holography of Infrasound as Observed from Natural and Artificial Sources.- Atmospheric Acoustics.- Coupling with the Ionosphere.- Past Field Experiments.- Present Field Experiments.- Future Developments.- References.- 18 Diagnostic Holography—A Feasibility Study.- Method.- Results and Discussion.- References.- 19 Acoustical Imaging of Biological Tissue—Holography and Direct Imaging.- Detection with the Sokolov Ultrasound Camera.- Synthesis of Three-Dimensional Images.- Holographic Recording With FM.- Summary.- References.- 20 Thin Liquid Layers for the Detection and Amplification of Ultrasonic Interference Patterns.- Surface Deformations.- A High-Pass Filter for Liquid-Surface Deformations.- Relaxation Behavior of Thin Liquid Layers.- Amplification of Acoustically Induced Surface Deformations.- Amplification Properties of Thin Liquid Layers.- Conducting Surfaces.- Nonconducting Surfaces.- Examples of Amplifying Detectors.- Design of the Acoustical Holography Experiment.- Aberrations.- The Optical System.- The Detector.- The Acoustical System.- Experimental Results.- Conclusions.- References.- 21 Acoustical Holography with Real-Time Color Translation.- Acoustical Characteristics.- Electronics.- Optics.- Results.- 22 Color Acoustical Holography.- Experimental Configuration.- Method of Reconstruction.- Color-Coding Techniques and Results.- Summary.- References.- 23 Higher-Order Images from Grating-Like Acoustical Holograms and Their Multiplexing and Multicolor Applications.- Some Properties of the Higher-Order Images Reconstructed from Grating-Like Acoustical Holograms.- Construction of Grating-Like Acoustical Holograms and Optical Reconstruction of Higher-Order Images.- Contrast Enhancement of Higher-Order Images.- Contrast Inversion of Higher-Order Images.- Higher-Order Images Reconstructed from Acoustical Holograms by a Two-Beam Interference Method.- Higher-Order Images Reconstructed from Acoustical Holograms by an Electronic Reference Method.- Space-Division-Multiplexing Acoustical Holography.- Theory.- Experiment.- Multicolor Acoustical Holography.- Theory.- Preliminary Experiment.- Conclusion.- References.- 24 Long-Wavelength Holography and Visual Reproduction Methods.- 25 A New Method for Studying Acoustic Radiation Using Long-Wavelength Acoustical Holography.- Experimental Demonstration.- Conclusions.- 26 Supplementary Bibliography.