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

Abstract

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.

Official source

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

Abstract

Official source

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

About this result

Related concepts (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).

Oversampling

In signal processing, oversampling is the process of sampling a signal at a sampling frequency significantly higher than the Nyquist rate. Theoretically, a bandwidth-limited signal can be perfectly reconstructed if sampled at the Nyquist rate or above it. The Nyquist rate is defined as twice the bandwidth of the signal. Oversampling is capable of improving resolution and signal-to-noise ratio, and can be helpful in avoiding aliasing and phase distortion by relaxing anti-aliasing filter performance requirements.

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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