Nicolas C. Pégard

Three-dimensional deconvolution microfluidic microscopy using a tilted channel

Abstract. We have developed a microfluidic device that enables the computation of three-dimensional (3-D) images of flowing samples. Using a microfluidic channel that is tilted along the optical axis, we record several progressively defocused images of the flowing sample as it passes across the focal plane. The resulting focal stack is then deconvolved to generate 3-D images. Experimental results on flowing yeast cells reveal both volume and surface profile information. The microfluidic channel eliminates the need for a precise translation stage to control defocusing and enables high sample throughput in an insulated, nontoxic, liquid environment. The experimental device can be implemented in all existing microscopes as a modified slide stage and is ideally suited for 3-D profiling in flow cytometers.

Optimizing holographic data storage using a fractional Fourier transform.

We demonstrate a method to optimize the reconstruction of a hologram when the storage device has a limited dynamic range and a minimum grain size. The optimal solution at the recording plane occurs when the object wave has propagated an intermediate distance between the near and far fields. This distance corresponds to an optimal order and magnification of the fractional Fourier transform of the object.

3D microfluidic microscopy using a tilted channel

We present a 3D microfluidic microscope. Using a microfluidic channel that is tilted along the optical axis of the objective, we record and deconvolve a focal stack as the sample passes across the focal plane.

Flow-Scanning Microfluidic Imaging

The advantages of microfluidics for fast analysis of microscopic suspensions have led to the commercial development of flow cytometers. In this chapter, we propose new micro‐ scopy methods that combine controlled motion of micro-organisms in a laminar micro‐ fluidic flow, optics, and computation. We propose three new imaging modalities. We first introduce a flow-based version of structured illumination microscopy, where the necessa‐ ry phase shifts are no longer obtained by controlled displacement of the illumination pat‐ tern but by flowing the sample itself. Then, we propose a three-dimensional (3D) deconvolution microscopy method with a microfluidic device for continuous acquisition of gradually defocused images. Finally, we introduce a microfluidic device for phasespace image acquisition, and computational methods for the reconstruction of either phase of intensity, in 3D. The imaging modalities we introduce all retain the benefits of fluid systems for noninvasive bioimaging. The proposed devices can easily be integrated on existing microscopes as a modified microscope slide, or on flow cytometers, and aquatic imagers with minor adjustments. Alternative on-chip implementations are also possible, with lens-free devices, and near-field optical and microfluidic elements directly assembled on the surface of a CCD (Charge-Coupled Device) or CMOS (Complementary metal–oxide–semiconductor) chip.

3D Amplitude and Phase Imaging Using Flow-scanning Tomography

We combine a microfluidic channel and hybrid space-angle measurement to observe live biomaterial in motion. We experimentally demonstrate the technique by co-registering 3D absorption and 3D differential-phase-contrast images on live, freely swimming C.elegans nematodes.

3D Microfluidic Microscopy

Using sample flow as an extra degree of freedom for imaging, we present several marker-free methods of 3D surface profiling and tomography. Examples are given on live flowing yeast cells and freely swimming C. elegans.

Microfluidic Structured Illumination Microscope

We apply the principle of structured illumination to microfluidic microscopy. Sample flow across the illumination pattern automatically gives the necessary phase shifts. We experimentally demonstrate the technique by reconstructing a superresolution image of yeast cells.

3D deconvolution microscopy using a microfluidic tilted channel

We present a 3D microfluidic microscope. Focal stacks are recorded by observing samples flowing through a tilted microfluidic channel and then digitally deconvolved. Experimental results are shown on flowing yeast cells.

3D microscopy using a tilted microfluidic channel

We introduce a microfluidic microscope with 3D imaging capabilities. Using a tilted capillary channel, we collect and deconvolve focal stacks of a flowing sample to retrieve a volume image. Experiments on yeast cells are shown.

Fractional optics for image processing and measurement

Fractional optics involves the study of optical phenomena with fractional orders, for example, fractional Fourier transforms and fractional vortices. We review our work on the applications of fractional optics in image processing and measurement.