Digital Holographic Microscopy (DHM)

2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2007

Digital holographic microscopy (DHM) is applied to life sciences applications and demonstrate its capability of real-time imaging and quantitative measurements of physiological parameters such as cell volume or mean cell hemoglobin concentration (MCHC) of erythrocyte cells. DHM has the advantage to be non-invasive (no phototoxicity, no contrast agents) and allows a high throughput measurements.

Biomedical Optics, 2006

We demonstrate in Digital Holographic Microscopy a self-calibration hologram method allowing aberrations compensation and a real-time biological cell phase recovery by using a single hologram without adjustment of any parameters.

Applied Optics, 2004

A parameter-optimized off-axis setup for digital holographic microscopy is presented for simultaneous, high-resolution, full-field quantitative amplitude and quantitative phase-contrast microscopy and the detection of changes in optical path length in transparent objects, such as undyed living cells. Numerical reconstruction with the described nondiffractive reconstruction method, which suppresses the zero order and the twin image, requires a mathematical model of the phase-difference distribution between the object wave and the reference wave in the hologram plane. Therefore an automated algorithm is explained that determines the parameters of the mathematical model by carrying out the discrete Fresnel transform. Furthermore the relationship between the axial position of the object and the reconstruction distance, which is required for optimization of the lateral resolution of the holographic images, is derived. The lateral and the axial resolutions of the system are discussed and quantified by application to technical objects and to living cells.

Biomedical Optics and 3-D Imaging, 2012

Biomedical Optics Express, 2014

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 highvisibility 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.

2008

We report the development of a simple commercial digital holographic microscope. The hologram is recorded using a CCD sensor and numerically reconstructed to provide quantitative analysis of the object. The laser source is coupled via fibre optics and the opto-mechanical setup is flexible and customizable for either the reflection or transmission mode. The user-friendly software allows live reconstruction, simultaneously providing both the amplitude and phase images. System performance is improved with phase unwrapping and interferometric comparison. Additional features include various image enhancements, cross-sectional and line profiling, measurement and data analysis tools for quantitative 3D imaging and surface topography measurement. The performance of the product is tested on different micro devices, glass and silicon surfaces.

Optics Letters, 2012

Digital holographic microscopy (DHM) is one of the most effective techniques used for quantitative phase imaging of cells. Here we present a compact, easy to implement, portable, and very stable DHM setup employing a selfreferencing Lloyd's mirror configuration. The microscope is constructed using a diode laser source and a CMOS sensor, making it cost effective. The reconstruction of recorded holograms yields the amplitude and phase information of the object. The temporal stability of the presented technique was found to be around 0.9 nm without any vibration compensation, which makes it ideal for studying cell profile changes. This aspect of the technique is demonstrated by studying membrane fluctuations of red blood cells.

Optics letters, 1998

We applied phase-shifting digital holography to microscopy by deriving the complex amplitude of light scattered from microscopic three-dimensional objects through a microscope objective by video camera recording, phaseshifting analysis, and computer reconstruction. This method requires no mechanical movement and provides a f lexible display and quantitative evaluation of the reconstructed images. A theory of image formation and experimental verification with specimens are described.

Journal of Biomedical Optics, 2014

The advantages of using a telecentric imaging system in digital holographic microscopy (DHM) to study biological specimens are highlighted. To this end, the performances of nontelecentric DHM and telecentric DHM are evaluated from the quantitative phase imaging (QPI) point of view. The evaluated stability of the microscope allows single-shot QPI in DHM by using telecentric imaging systems. Quantitative phase maps of a section of the head of the drosophila melanogaster fly and of red blood cells are obtained via single-shot DHM with no numerical postprocessing. With these maps we show that the use of telecentric DHM provides larger field of view for a given magnification and permits more accurate QPI measurements with less number of computational operations.

DOAJ (DOAJ: Directory of Open Access Journals), 2013

Red blood cells are able to undergo shape change from the "normal" discocyte to either echinocytes or stomatocytes depending on a large variety of membrane and cytoplasmic parameters. Such shape changes can be relatively fast (within seconds) during the sedimentation of the cells in suspension or after the cells are getting in contact with artificial surfaces. High resolution digital holographic microscopy has been applied to study these processes. This method represents a new setup allowing a contact-less and marker-free quantitative phase-contrast imaging of living cells under conventional laboratory conditions. With the applied technique we were able to detect and analyse fast shape changes of red blood cells.