High throughput holographic imaging-in-flow for the analysis of a wide plankton size range

Catherine Yourassowsky,Frank Dubois

doi:10.1364/oe.22.006661

Abstract

We developed a Digital Holographic Microscope (DHM) working with a partial coherent source specifically adapted to perform high throughput recording of holograms of plankton organisms in-flow, in a size range of 3 µm-300 µm, which is of importance for this kind of applications. This wide size range is achieved with the same flow cell and with the same microscope magnification. The DHM configuration combines a high magnification with a large field of view and provides high-resolution intensity and quantitative phase images refocusing on high sample flow rate. Specific algorithms were developed to detect and extract automatically the particles and organisms present in the samples in order to build holograms of each one that are used for holographic refocusing and quantitative phase contrast imaging. Experimental results are shown and discussed.

Highlights

Different techniques were developed to perform high throughput imaging-in-flow of aquatic microorganisms for various applications e.g. harmful algal blooms monitoring [1,2], and plankton population studies [3,4,5].The goal of these techniques is to combine the recording of high-resolution digital optical microscopy images with a high throughput flow rate
We describe the processing steps to obtain the complex amplitude information of each individual particle and organism flowing inside the capillary in the field of view (FOV) of the Digital Holographic Microscope (DHM)
It makes sense to use detection with a camera triggering if there are few particles in the flow in such a way that a sequence should present numerous holograms without particles

Summary

Introduction

Different techniques were developed to perform high throughput imaging-in-flow of aquatic microorganisms for various applications e.g. harmful algal blooms monitoring [1,2], and plankton population studies [3,4,5].The goal of these techniques is to combine the recording of high-resolution digital optical microscopy images with a high throughput flow rate. Thanks to a phase plate inserted between the microscope lens and the detector, it increases the depth of field by a factor 4 (for a microscope equipped with a 4X microscope lens), allowing to record images of aquatic organisms and particles in a dynamic flow and to improve the volume analysis rate. This instrument can work with microscope lenses up to magnification 20X and with specific flow cells with a depth adapted to the magnification. For the recording of all the organisms in the sample, more specific flow cell must be used and with a maximum magnification of the microscope lens limited to 10x

Methods

Results

Conclusion