Search results for " microscopy"
showing 10 items of 1617 documents
Digital Holographic Microscopy: A New Imaging Technique to Quantitatively Explore Cell Dynamics with Nanometer Sensitivity
2014
In the first part of this chapter, we describe how the new concept of digital optics applied to the field of holographic microscopy has made it possible to quantitatively and accurately measure the phase retardation induced on the transmitted wavefront by the observed transparent specimen, allowing thus to develop a reliable and flexible digital holographic quantitative phase microscopy (DH-QPM). In the second part the most relevant DH-QPM applications in the field of cell biology are presented. Particularly, applications taking directly advantage of benefits provided by digital optics particularly off-line autofocusing and extended depth of focus, are outlined. Otherwise, special emphasis …
Evaluation of the use of wavefront encoding to reduce depth-induced aberration in structured-illumination microscopy
2018
Three-dimensional imaging is affected by depth-induced spherical aberration (SA) when imaging deep into an optically thick sample. In this work, we evaluate the impact of SA on the performance of incoherent grating-projection structured illumination microscopy (SIM). In particular, we analyze the reduction of the contrast in the structured pattern and compare the reconstructed SIM images for different amounts of SA. In order to mitigate the impact of SA, we implement and evaluate in SIM a wavefront encoded imaging system using a square cubic (SQUBIC) phase mask, an approach shown previously to be successful in conventional microscopy.
Physical compensation of phase curvature in digital holographic microscopy by use of programmable liquid lens.
2015
Quantitative phase measurements obtained with digital holographic microscopes are strongly dependent on the optical arrangement of the imaging system. The nontelecentric operation provides phase measurements affected by a parabolic phase factor and requires numerical postprocessing, which does not always remove all the perturbation. Accurate phase measurements are achieved by using the imaging system in telecentric mode. Unfortunately, this condition is not accomplished when a commercial microscope is used as the imaging system. In this paper, we present an approach for obtaining accurate phase measurements in nontelecentric imaging systems without the need for numerical postprocessing. The…
Superresolved common-path phase-shifting digital inline holographic microscopy using a spatial light modulator.
2012
Common-path phase-shifting lensless holographic microscopy has been recently proposed as a novel approach capable of high numerical aperture imaging in a lensless digital inline holographic microscopy layout [Opt. Lett.35, 3919 (2010)]. Here we present proof-of-concept validation for improving the resolution limit imposed by diffraction in such a setup. This is accomplished by shifting the phase lens displayed at the spatial light modulator, which moves the illumination point source to different off-axis positions. For each off-axis position, a set of inline phase-shifted holograms are recorded by the digital sensor and stored at the computer’s memory for later digital postprocessing. As a …
Quantitative Phase Imaging in Microscopy Using a Spatial Light Modulator
2010
In this chapter, we present a new method capable of recovery of the quantitative phase information of microscopic samples. Essentially, a spatial light modulator (SLM) and digital image processing are the basics to extract the sample’s phase distribution. The SLM produces a set of misfocused images of the input sample at the CCD plane by displaying a set of lenses with different power at the SLM device. The recorded images are then numerically processed to retrieve phase information. Computations are based on the wave propagation equation and lead to a complex amplitude image containing information of both amplitude and phase distributions of the input sample diffracted wave front. The prop…
Leakage radiation microscopy of surface plasmon coupled emission: investigation of gain-assisted propagation in an integrated plasmonic waveguide.
2010
International audience; Using a single-mode dielectric-loaded surface plasmon polariton waveguide doped with quantum dots, we were able to slightly increase the propagation length of the mode by stimulated emission of plasmon. We analyse the amplification phenomenon in the visible range by combining leakage radiation microscopy and surface plasmon coupled emission techniques.
In-Depth Investigation of the Safety of Wooden Shelves Used for Traditional Cheese Ripening
2021
ABSTRACT The main goal of this research was to characterize the bacterial diversity of the wooden boards used for aging traditional Sicilian cheeses and to evaluate whether pathogenic bacteria are associated with these surfaces. Eighteen cheese dairy factories producing three traditional cheese typologies (PDO Pecorino Siciliano, PDO Piacentinu Ennese, and Caciocavallo Palermitano) were selected within the region of Sicily. The wooden shelf surfaces were sampled by a destructive method to detach wood splinters as well as by a nondestructive brushing to collect microbial cells. Scanning electron microscopy showed the presence of almost continuous bacterial formations on the majority of the s…
Manipulation of nanoparticles of different shapes inside a scanning electron microscope
2014
In this work polyhedron-like gold and sphere-like silver nanoparticles (NPs) were manipulated on an oxidized Si substrate to study the dependence of the static friction and the contact area on the particle geometry. Measurements were performed inside a scanning electron microscope (SEM) that was equipped with a high-precision XYZ-nanomanipulator. To register the occurring forces a quartz tuning fork (QTF) with a glued sharp probe was used. Contact areas and static friction forces were calculated by using different models and compared with the experimentally measured force. The effect of NP morphology on the nanoscale friction is discussed.
Chemical microimaging and microspectroscopy of surfaces with a photoemission microscope
1997
We applied element sensitive photoemission electron microscopy (PEEM) to investigate surfaces of devices built from complex materials. Conventional PEEM suffers from lack of information about the chemical composition of the imaged surface. Such information can be obtained by PEEM via tuning the photon energy to X-ray absorption edges. To apply spectromicroscopy we acquired and subtracted microscopic images using photon energies just below and at the edges. The resulting difference gives a micro-image of the lateral distribution of a specific element. Microspectroscopy is performed by recording the intensity of secondary electrons in selected spots during a sweep of the photon energy. We app…
The lateral variation of solid state reactions at surfaces studied by means of photoemission electron microscopy: formation of titanium silicides
2001
The alloying and oxygen reduction at titanium silicon interfaces were studied by means of photoemission microscopy. The microscopic chemical composition of the sample surface was characterised by means of imaging X-ray absorption. The silicide formation was studied at clean and oxidised silicon substrates both covered with micron-sized titanium patterns.