Temporal reference acoustical holography

Area of Science:

• Acoustical holography
• Optical interferometry
• Laser-based imaging

Background:

• Traditional holography requires a reference wave, complicating acoustic hologram recording.
• Existing methods for acoustic holography are limited by recording time and aperture size.

Purpose of the Study:

• To introduce a new holography technique that removes the requirement for a reference wave.
• To demonstrate the recording and reconstruction of temporal reference acoustical holograms using optical methods.

Main Methods:

• Utilized a Sokolov ultrasound camera system for initial acoustic hologram recording.
• Developed an optical method using a double-pulsed ruby laser with a quarter wavelength shift for recording.
• Investigated a second optical method employing a scanning continuous-wave (cw) laser.

Main Results:

• Successfully obtained reconstructions from a temporal reference acoustical hologram recorded at 4.8 MHz.
• Demonstrated that optical recording allows for subfringe interferometric holograms of vibrating surfaces.
• Showcased that reconstructed intensity is linearly proportional to surface displacement.

Conclusions:

• The new optical techniques significantly reduce recording time, improving tolerance to object motion.
• These methods enable the recording of larger aperture temporal reference acoustical holograms compared to conventional approaches.
• Eliminates complex electronic detection, replacing it with high-bandwidth optical recording for direct remote sensing of acoustic waves.