Physical Principles of the Method for Determination of Geometrical Characteristics and Particle Recognition in Digital Holography

Dyomin, Victor; Polovtsev, Igor; Davydova, Alexandra

doi:10.1007/s11182-018-1323-8

Cited by 2 publications

(2 citation statements)

References 5 publications

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“…The DHC registers a digital hologram of the entire volume of the medium with studied particles per exposure (laser diode pulse). The particle images are reconstructed numerically from a preprocessed digital hologram by calculating the diffraction integral [1][2][3], and further processing of holographic images [23,24], including determining the best image plane of the particle, allows detecting the spatial distribution of particles (three-dimensional coordinates of each particle), size, shape, speed, and direction of movement of each particle, and ensuring their recognition [24,25] (Figure 1d). In other words, the DHC technology, which is digital hologram recording, reconstruction of particle images from it, and processing of holographic images, makes it possible to create a virtual 3D image of the volume with test particles.…”

Section: Digital Holographic Cameramentioning

confidence: 99%

“…In a holographic study of real particles under natural conditions, for example, plankton and other marine particles, it is impossible to compare the reconstructed image with the reference image. Moreover, the accurate determination of the size and shape of the particle based on its holographic image [24,25], as well as its recognition, require a clear definition of the image boundary, which, in turn, requires accurate digital focusing, i.e., to determine the value z at which the image is of the highest quality (sharp). To assess the digital focusing quality of reconstructed particle images, we will use the quality indicators of the particle image reconstructed from the digital hologram-boundary contrast K and boundary intensity jump P at the boundary of the particle image [29].…”

Section: Holographic Particle Image Quality Indicatorsmentioning

confidence: 99%

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Features of the Application of Coherent Noise Suppression Methods in the Digital Holography of Particles

et al. 2023

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The paper studies the influence of coherent noises on the quality of images of particles reconstructed from digital holograms. Standard indicators (for example, signal-to-noise ratio) and such indicators as the boundary contrast and boundary intensity jump previously proposed by the authors are used to quantify the image quality. With the use of these parameters, for examples of some known methods of suppressing coherent noises in a holographic image (eliminating the mutual influence of virtual and real images in in-line holography, and time averaging), the features and ranges of applicability of such correction were determined. It was shown that the use of the complex field amplitude reconstruction method based on the Gerchberg–Saxton algorithm and the spatial-frequency method improves the quality of determining the particle image boundary (by boundary intensity jump) starting from the distance between a hologram and a particle, which is about twice the Rayleigh distance. In physical experiments with model particles, averaging methods were studied to suppress non-stationary coherent noises (speckles). It was also shown that averaging over three digital holograms or over three holographic images is sufficient to provide a quality of particle image boundary suitable for particle recognition. In the case of multiple scattering, when it is necessary to impose a limit on the working volume length (depth of scene) of the holographic camera, the paper provides estimates that allow selecting the optimal working volume length. The estimates were made using the example of a submersible digital holographic camera for plankton studies.

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