Off-axis digital holographic camera for quantitative phase microscopy.

Zahra Monemhaghdoust,Christian Depeursinge,Frédéric Montfort,Yves Emery,Christophe Moser

doi:10.1364/boe.5.001721

Zahra Monemhaghdoust, Christian Depeursinge + Show 3 more

Open Access

https://doi.org/10.1364/boe.5.001721

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Abstract

We propose and experimentally demonstrate a digital holographic camera which can be attached to the camera port of a conventional microscope for obtaining digital holograms in a self-reference configuration, under short coherence illumination and in a single shot. A thick holographic grating filters the beam containing the sample information in two dimensions through diffraction. The filtered beam creates the reference arm of the interferometer. The spatial filtering method, based on the high angular selectivity of the thick grating, reduces the alignment sensitivity to angular displacements compared with pinhole based Fourier filtering. The addition of a thin holographic grating alters the coherence plane tilt introduced by the thick grating so as to create high-visibility interference over the entire field of view. The acquired full-field off-axis holograms are processed to retrieve the amplitude and phase information of the sample. The system produces phase images of cheek cells qualitatively similar to phase images extracted with a standard commercial DHM.

Highlights

Digital holographic microscopy (DHM) is a quantitative optical imaging technique that is able to capture the complex wavefront of the light interacting with a sample [1,2,3]
We propose and experimentally demonstrate a digital holographic camera which can be attached to the camera port of a conventional microscope for obtaining digital holograms in a self-reference configuration, under short coherence illumination and in a single shot
The spatial filtering method, based on the high angular selectivity of the thick grating, reduces the alignment sensitivity to angular displacements compared with pinhole based Fourier filtering

Summary

Introduction

Digital holographic microscopy (DHM) is a quantitative optical imaging technique that is able to capture the complex wavefront (amplitude and phase) of the light interacting with a sample [1,2,3]. Capturing the wavefront is performed by recording the spatial interference pattern of the beam that interacts with the sample (i.e. object beam) and a mutually coherent reference beam using a digital camera. On-axis digital holographic microscopy works with broadband light, parasitic interference is reduced but requires acquiring multiple interferograms which limits the ability to perform real-time imaging and adds complexity to the system. Under broadband illumination and in order to be able to exploit the whole field of view of the camera in off-axis geometry, the coherence planes of the two beams must be parallel. We and others have shown that coherence plane manipulation on the reference beam allows for full field imaging in off-axis geometry [5,6]

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