Digital synthesis of multiple off-axis holograms with overlapping Fourier spectra

Bühl, Johannes; Babovsky, Holger; Kießling, A.; Kowarschik, R.

doi:10.1016/j.optcom.2010.05.038

Cited by 22 publications

(15 citation statements)

References 14 publications

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“…As the overlapping increases, the reconstruction becomes more accurate but a higher number of recordings are needed. Recently, Bühl et al reported on a method to correctly overlap the different recordings in SA digital holography 45 . Here, we have adopted a similar strategy where 3 factors are considered in order to digitally synthesize a high quality superresolved image.…”

Section: System Analysismentioning

confidence: 99%

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Synthetic aperture engineering for super-resolved microscopy in digital lensless Fourier holography

et al. 2011

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We present a method capable to improve the resolution limit of an imaging system in digital lensless Fourier holographic configuration. The method is based on angular-and time-multiplexing of the object's spatial frequency information. On one hand, angular multiplexing is implemented by using tilted beam illumination to get access to high order spectral frequency bands of the of the object's spectrum. And, on the other hand, time multiplexing is needed to cover different directions at the spatial frequency domain. This combination of angular-and time-multiplexing in addition with holographic recording allows the complex amplitude recovery of a set of elementary apertures covering different portions of the object's spectrum. Finally, the expanded synthetic aperture (SA) is generated by coherent addition of the set of recovered elementary apertures. Such SA expands up the cut-off frequency limit of the imaging system and allows getting a superresolved image of the input object. Moreover, if a priori knowledge about the input object is available, customized SA shaping is possible by considering the addition of those elementary apertures corresponding with only the directions of interest and, thus, reducing the whole consuming time of the approach. We present experimental results in concordance with theoretical predictions for two different resolution test objects, for different SA shapes, and considering different resolution gain factors.

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Section: System Analysismentioning

confidence: 99%

“…This procedure is repeated for each elementary pupil used in the experiment. Although the whole process can be guided by computer using an image quality criterion as in [45], here the final reconstructed image is obtained by visual evaluation of the reconstructed image quality every time that a new bandpass image is added to the others.…”

Section: System Analysismentioning

confidence: 99%

Synthetic aperture engineering for super-resolved microscopy in digital lensless Fourier holography

et al. 2011

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“…more holograms, that preserves object data but with a different distribution in the speckle noise. The concept of devising a synthetic aperture is one of these optical methods [26][27][28]. This concept is based on acquiring different holograms and subsequently arranging them properly for the numerical reconstruction process.…”

Section: Introductionmentioning

confidence: 99%

Assessing digital micromirror devices for speckle noise control in digital holography

Gaviria-Mesa¹,

Hincapie²,

Garcı́a-Sucerquia³

et al. 2017

Opt. Pura Apl.

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ABSTRACT:Speckle noise is a common issue in coherent imaging techniques. As one of these techniques, digital holography (DH) is affected by this problem. Although several attempts have been made to overcome speckle noise in the numerical reconstruction of digitally recorded holograms, there still exists the need for fast and effective methods to get rid of speckle and improve image quality. We assess the suitability of a digital micromirror device (DMD) as modulator of the object illumination in a digital holographic setup, where the DMD acts generating speckle-like patterns that are projected onto the object. These patterns change the object beam in a random way. Several holograms, each with a different pattern in the object illumination, are recorded and numerically reconstructed. The image with reduced speckle noise is the result of a superposition in an intensity basis of various such reconstructions. The feasibility of the method is validated by experimental results.Key words: Digital holography; Speckle; Digital Micromirror Device RESUMEN:El ruido speckle es un problema inherente a las técnicas de formación de imágenes con luz coherente. Ya que la holografía digital es una de estas técnicas, también se ve afectada por este problema. Aunque se han hecho varios intentos por eliminar el ruido speckle en la reconstrucción numérica de hologramas registrados digitalmente, todavía existe la necesidad de métodos rápidos y efectivos para eliminar el speckle y mejorar la calidad de las imágenes reconstruidas. Nosotros evaluamos la conveniencia del uso de un dispositivo digital de microespejos (DMD) como modulador de la iluminación del objeto en un montaje holográfico digital. El DMD actúa generando patrones aleatorios tipo speckle que son proyectados sobre el objeto. Estos patrones cambian el haz objeto de una manera aleatoria y después interfiere formando el holograma. Se registran varios hologramas, cada uno con un patrón diferente en la iluminación del objeto, y se reconstruyen numéricamente. La imagen final con el ruido speckle reducido es el resultado de la superposición en intensidades de varias de estas reconstrucciones. La viabilidad del método es validada mediante resultados experimentales. [28] X. Cai and H. Wang, "The influence of hologram aperture on speckle noise in the reconstructed image of digital holography and its reduction", Opt. Commun. 281, 232-237 (2008).

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“…In this case, the process usually relies on the Fourier shift theorem; the object function is modulated, which causes a spectrum shift, bringing back spatial frequencies in the bandpass of the system. For example, a tilt can be introduced in the object [7][8][9] or in the plane wave illumination [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Tomographic diffractive microscopy and multiview profilometry with flexible aberration correction

et al. 2014

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We have developed a tomographic diffractive microscope in reflection, which permits observation of sample surfaces with an improved lateral resolution, compared to a conventional holographic microscope. From the same set of data, high-precision measurements can be performed on the shape of the reflective surface by reconstructing the phase of the diffracted field. Doing so allows for several advantages compared to classical holographic interferometric measurements: improvement in lateral resolution, easier phase unwrapping, reduction of the coherent noise, combined with the high-longitudinal precision provided by interferometric phase measurements. We demonstrate these capabilities by imaging various test samples.

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Digital synthesis of multiple off-axis holograms with overlapping Fourier spectra

Cited by 22 publications

References 14 publications

Synthetic aperture engineering for super-resolved microscopy in digital lensless Fourier holography

Synthetic aperture engineering for super-resolved microscopy in digital lensless Fourier holography

Assessing digital micromirror devices for speckle noise control in digital holography

Tomographic diffractive microscopy and multiview profilometry with flexible aberration correction

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