We report imaging of a sound field radiated from a sound source by parallel phase-shifting digital holography. We used a Nd:YVO4 laser emitting light with a wavelength of 532 nm as a light source and a polarization imaging camera to record holograms. The holograms were recorded 40000 Hz sound with 100000 frame per second. To adjust one wavelength of sound to the recordable area of the image sensor, we introduced a demagnification optical system in the path of the object beam. The phase difference images were calculated from the recorded holograms. Thus, we observed propagation of periodical phase distributions of sound and succeeded in sound field imaging.
We propose single-shot incoherent digital holography using parallel-phase shifting radial shearing interferometry. The object wave from an incoherently illuminated or self-luminous object is Fourier transformed, and enters a parallel phase-shifting radial shearing interferometer. Then, the radially sheared two object waves combines and the hologram whose phases are relatively shifted in every 2x2 pixels of the image sensor are generated. By applying parallel phaseshifting interferometry to the hologram, we obtain the amplitude and the phase of the complex spatial coherence function of the object wave. Then, the complex amplitude distribution of the object wave at arbitrary depth is calculated from the function. We applied the proposed technique to the three-dimensional imaging of two LEDs and experimentally demonstrated the proposed technique.
We propose parallel phase-shifting radial shearing interferometry and apply this technique to single-shot wavefront measurement. This technique records a single interference image consisting of the combination of radially sheared two object waves. By applying parallel phase-shifting interferometry and a wavefront reconstruction algorithm to the recorded single interference image, the phase image of the measuring object wave is obtained. We numerically simulated single-shot wavefront measurement by using the proposed technique. It was assumed that the object was two particles. The amplitude and phase images of the particles were assumed as Gaussian distribution. The cross-correlation coefficient between the original phase image and the phase image reconstructed by using the proposed technique was 0.984.
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