Acoustical holograms using phase information only

Area of Science:

• Acoustical Holography
• Optical Physics
• Signal Processing

Background:

• Optical signals necessitate square-law detectors, hindering direct phase measurement without a reference beam.
• Acoustic beams, however, are convertible to electrical signals via linear transducers, allowing electronic reference beam integration.

Purpose of the Study:

• To develop a method for acoustical holography enabling direct phase measurement of acoustic signals.
• To achieve high-fidelity reconstruction of two-dimensional objects using phase-only acoustical holograms.

Main Methods:

• Utilizing two phase-locked electronic reference beams to record only the phase of the acoustic signal.
• Implementing spatial filtering to eliminate conjugate image interference in coaxial holograms.
• Exploring the optical analogue using linear photographic film with intensity-dependent gamma.

Main Results:

• A novel scheme for acoustical holography was successfully demonstrated.
• The method allows for the recording of phase-only acoustical holograms with uniform fringe visibility.
• Improved two-dimensional object reconstructions were achieved through spatial filtering.

Conclusions:

• Acoustical holography with electronic reference beams offers a viable alternative to optical holography for phase measurement.
• The developed technique facilitates direct phase recording and accurate object reconstruction.
• Spatial filtering is crucial for enhancing reconstruction quality in coaxial holograms.