Publication

Suppression of the zero-order in off-axis digital holography through nonlinear filtering

Christian Depeursinge, Michaël Unser, Nicolas Pavillon, Jonas Kühn, Chandra Sekhar Seelamantula
2009
Journal Articles

Résumé

We present experimental validation of a new reconstruction method for off-axis digital holographic microscopy (DHM). This method effectively suppresses the object auto-correlation — namely the zero-order term — from holographic data, thereby improving the reconstruction bandwidth of complex wavefronts. The algorithm is based on nonlinear filtering; it can be applied to standard DHM setups, with realistic recording conditions. We study the robustness of the technique under different experimental configurations, and quantitatively demonstrate its enhancement capabilities on phase signals.

Source officielle

https://infoscience.epfl.ch/entities/publication/ec592d67-61ab-41ab-9f36-2015b897f781

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Christian Depeursinge, Michaël Unser, Nicolas Pavillon, Jonas Kühn, Chandra Sekhar Seelamantula
2009
Journal Articles

Résumé

Source officielle

https://infoscience.epfl.ch/entities/publication/ec592d67-61ab-41ab-9f36-2015b897f781

À propos de ce résultat

Concepts associés (21)

Reconstruction filter

In a mixed-signal system (analog and digital), a reconstruction filter, sometimes called an anti-imaging filter, is used to construct a smooth analog signal from a digital input, as in the case of a digital to analog converter (DAC) or other sampled data output device. The sampling theorem describes why the input of an ADC requires a low-pass analog electronic filter, called the anti-aliasing filter: the sampled input signal must be bandlimited to prevent aliasing (here meaning waves of higher frequency being recorded as a lower frequency).

Suréchantillonnage

Le suréchantillonnage ou sur-échantillonnage est une technique particulière d'échantillonnage. Elle consiste à échantillonner le signal à une fréquence très élevée, beaucoup plus que ne l'exigerait le théorème de Shannon. Le suréchantillonnage permet de : Faciliter la conception du filtre anticrènelage, (ou antirepliement, ou encore anti-aliasing) ; Diminuer le bruit présent dans la bande utile et d'augmenter le rapport signal sur bruit. Il est employé dans les convertisseurs sigma-delta.

Anti-aliasing filter

An anti-aliasing filter (AAF) is a filter used before a signal sampler to restrict the bandwidth of a signal to satisfy the Nyquist–Shannon sampling theorem over the band of interest. Since the theorem states that unambiguous reconstruction of the signal from its samples is possible when the power of frequencies above the Nyquist frequency is zero, a brick wall filter is an idealized but impractical AAF. A practical AAF makes a trade off between reduced bandwidth and increased aliasing.

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