Optical microscopy

Top PDF Optical microscopy:

Watching electrochemistry with BALM optical microscopy

Watching electrochemistry with BALM optical microscopy

kevin.jaouen@cea.fr Backside Absorbing Layer Microscopy (BALM) is a new optical microscopy technique developed by D. Ausserré at IMMM, which uses absorbing anti-reflection layers to achieve extreme contrast at an interface. It combines a sub-nm vertical sensitivity comparable to the one of AFM with the versatility and real- time imaging capabilities of an optical microscope. Recently, we showed how this technique allows observing 2D materials and their chemical modification with unprecedented Z-resolution (1).

2 En savoir plus

Optical microscopy for measuring tapered fibers beyond the diffraction limit

Optical microscopy for measuring tapered fibers beyond the diffraction limit

The counterpart of this ease of fabrication is an imperfect knowledge of the device profile, i.e. its diameter versus the light propagation axis. Indeed, device optimization may require an extremely accurate knowledge of this profile. As an example, in a silica nanofiber, phase matching for second harmonic generation can be obtained from a fundamental mode HE11 at 1550 nm towards a higher mode TM01 at 775 nm if the nanofiber diameter is 693 nm [ 21 ]. Efficient second harmonic generation in a 100 µm long nanofiber requires this diameter to be maintained with an accuracy of ± 20 nm. Measuring the profiles with such accuracies is highly demanding and, is not directly accessible with conventional optical microscopy. Although scanning electron microscopy (SEM) could be used to measure such profiles, this is a destructive method: the clamping of the nanofiber on the measurement substrate and the gold deposit required for SEM
En savoir plus

14 En savoir plus

A Flow-induced phase inversion in immiscible polymer blends containing a liquid-crystalline polymer studied by in situ optical microscopy

A Flow-induced phase inversion in immiscible polymer blends containing a liquid-crystalline polymer studied by in situ optical microscopy

(Received 13 August 1999; final revision received 27 March 2000) Synopsis The phase inversion from a morphology of hydroxypropylcellulose in water 共HPC50%兲 droplets in polydimethylsiloxane 共PDMS兲 matrix to a morphology of PDMS droplets in HPC50% matrix can be induced by a change of shear rate, due to a viscosity ratio inversion. Such a process passing through four different transient morphological stages was studied by optical microscopy in a transparent shear device. In a certain concentration region, at a fixe shear rate, after sheets of PDMS were formed, the transition ‘‘hesitates’’ between phase inversion and refine starting morphology. The influenc of PDMS concentration, shear rate, elasticity, and phase dimension on the fina morphology was investigated and compared with different models given in the literature. The influenc of concentration and shear rate on the duration of the transient flo was also studied. We propose a simplifie model of breakage of filament to explain a part of our results. © 2000
En savoir plus

21 En savoir plus

Visualization of Mouse Neuronal Ganglia Infected by Herpes Simplex Virus 1 (HSV-1) Using Multimodal Non-Linear Optical Microscopy

Visualization of Mouse Neuronal Ganglia Infected by Herpes Simplex Virus 1 (HSV-1) Using Multimodal Non-Linear Optical Microscopy

Multimodal non-linear optical microscopy platform For the multiphoton microscopy, we used a laser scanning inverted microscope (Till Photonics GmbH, Munich, Germany). The focusing objective used in our experiments was the Olympus UAPO 40XW3/340 (water immersion with a numerical aperture of 1.15). The size of the laser beams at the entrance of the XY scanner was set to ensure that the aperture of the focusing objective was completely illuminated. Its position relative to the sample was controlled by a mechanic and a piezoelectric motor for coarse and fine adjustment. Because the imaged samples were thick, the detection was performed in the backward direction. CARS and two-photon fluorescence light was then collected with the same microscope objective, and redirected to a PMT detector (model R6357, Hamamatsu Corporation, New Jersey, USA) by a dichroic mirror (model FF735-Di01-25, Semrock, Rochester, USA). Additional filters are put in front of the detector to eliminate residual laser beams and isolate the desired signal.
En savoir plus

9 En savoir plus

Revealing the sub-50 ms electrochemical conversion of silver halide nanocolloids by stochastic electrochemistry and optical microscopy

Revealing the sub-50 ms electrochemical conversion of silver halide nanocolloids by stochastic electrochemistry and optical microscopy

In order to confirm such fast transformation events, they are probed by an interferometric optical microscopy (BALM), as it allows discriminating AgX NPs appearing as dark contrast features from metallic Ag NPs resulting in bright contrast features. Optical transients allow probing single NP collision and conversion at a transparent electrode. Such optical nanocollisions explain the low EC collision frequency in coulometry and confirm that NP collisions with the electrode surface yield their complete conversion. Finally, both EC and optical information confirm the up to 3 orders of magnitude faster conversion for Brownian NPs than for their surface- bound counterparts, which is related to differences in dynamic (transport and hopping charge transfer) involved during the reduction of the Brownian NPs. The fast reversible and complete conversion of AgX NPs into Ag NPs is comparable to the reverse reaction: the oxidation of Ag NPs into AgX NPs. This should make the Ag/AgX Brownian NPs an interesting candidate as a redox nanofluid in semi-solid redox flow cells. Meanwhile EC collision strategies provide a unique means to screen those nanofluid potentialities by probing the intrinsic charge capacity and charging rate of its individual NP constituents.
En savoir plus

9 En savoir plus

Combining laser diffraction, flow cytometry and optical microscopy to characterize a nanophytoplankton bloom in the Northwestern Mediterranean

Combining laser diffraction, flow cytometry and optical microscopy to characterize a nanophytoplankton bloom in the Northwestern Mediterranean

Compared to optical microscopy observations in the range 1–15 µm, the average of particles detected by the LISST is larger than that esti- mated by microscopy ( Fig. 6 ). This can be partly linked to the lugol fixation of samples (up to 10% decrease in diameter, Montagnes et al., 1994 ) but the LISST also assumes particle sphericity which could in- fluence its counting ( Karp-Boss et al., 2007 ). The abundance estimated by optical microscopy is much smaller than the LISST abundance. Based on the good agreement between LISST and cytometry abundances ( Fig. 4 ), we suspect an underestimation of abundance by optical mi- croscopy for this size range, possibly linked to the non-counting of aggregates containing cells. In terms of phytoplanktonic composition, microscopy analysis showed a large nanophytoplanktonic abundance with dominance of nano flagellates and actively growing nanodiatoms dominated by Minidiscus trioculatus (numerous dividing cells). The size range of these diatoms (diameter of 1–5 µm when the cell is not in di- vision) is consistent with the LISST 2 –11 µm peak.
En savoir plus

13 En savoir plus

Direct mineralogical imaging of economic ore and rock samples with multi-modal nonlinear optical microscopy

Direct mineralogical imaging of economic ore and rock samples with multi-modal nonlinear optical microscopy

Mung-Chung Kao 1 , Adrian F. Pegoraro 2 , David M. Kingston 3 , Albert Stolow 2,3,4 , Wen-Chuan Kuo 1 , Patrick H. J. Mercier 3 , Ankur Gogoi 1,5 , Fu-Jen Kao 1 & Andrew Ridsdale 3 Multi-modal nonlinear optical (NLO) microscopy, including stimulated Raman scattering (SRS) and second harmonic generation (SHG), was used to directly image mineralogical features of economic ore and rock samples. In SRS/SHG imaging, ore samples generally require minimal preparation and may be rapidly imaged, even in their wet state. 3D structural details, at submicron resolution, are revealed tens of microns deep within samples. Standard mineral imaging based on scanning electron microscopy (SEM), with elemental analysis via energy dispersive X-Ray spectroscopy, was used to independently validate the mineral composition of the samples. Spatially-resolved SRS from dominant Raman- resonant bands precisely maps the locations of speciic minerals contained within the samples. SHG imaging reveals locally non-centrosymmetric structures, such as quartz grains. Competing absorption and nonlinear scattering processes, however, can reduce contrast in SRS imaging. Importantly, the correlation between standard electron microscopy and multi-modal NLO optical microscopy shows that the latter ofers rapid image contrast based on the mineral content of the sample.
En savoir plus

10 En savoir plus

Optical microscopy to study single nanoparticles electrochemistry: From reaction to motion

Optical microscopy to study single nanoparticles electrochemistry: From reaction to motion

Optical microscopy: OMs are gaining more and more popularity. [23] They possess many advantages starting with the ability to visualize NPs in-situ, in real time with high temporal (up to 1 kHz) and high spatial (down to <20 nm) resolution, which is perfectly adapted to the accurate operando tracking of NP structural or compositional changes and discrete motion during EC activity, as summarized in Figure 1. In addition, OMs possess a wide field of view ensuring a high throughput screening and the possibility to collect huge amounts of data for post-processing and machine learning. [24]
En savoir plus

11 En savoir plus

Watching electrochemistry with BALM optical microscopy

Watching electrochemistry with BALM optical microscopy

kevin.jaouen@cea.fr Backside Absorbing Layer Microscopy (BALM) is a new optical microscopy technique developed by D. Ausserré at IMMM, which uses absorbing anti-reflection layers to achieve extreme contrast at an interface. It combines a sub-nm vertical sensitivity comparable to the one of AFM with the versatility and real- time imaging capabilities of an optical microscope. Recently, we showed how this technique allows observing 2D materials and their chemical modification with unprecedented Z-resolution (1).

2 En savoir plus

Advanced optical microscopy toolkits for non-invasive imaging in oncology

Advanced optical microscopy toolkits for non-invasive imaging in oncology

In the present thesis, examples of such applications of optical tools will be presented, including: (1) the assessment of cellular oxidative stress in ex vivo human[r]

272 En savoir plus

Fluorescence imaging on the nanoscale : bioimaging using near-field scanning optical microscopy

Fluorescence imaging on the nanoscale : bioimaging using near-field scanning optical microscopy

Chemical Society. Apertureless approaches have demonstrated a significant improvement in spatial 480 resolution over aperture-based near field approaches and have the added advantage of avoiding the use of fragile-optical fiber based probes. However, they suffer from three significant restrictions that have so far prevented their wide-spread use, particularly for biological imaging. First, photobleaching is more problematic than in normal fluorescence microscopy, since the focused laser beam used to

21 En savoir plus

Backside Absorbing Layer Microscopy: a New Tool to Study the Optical, Chemical and Electrochemical Properties of 2D Materials

Backside Absorbing Layer Microscopy: a New Tool to Study the Optical, Chemical and Electrochemical Properties of 2D Materials

Backside Absorbing Layer Microscopy: a New Tool to Study the Optical, Chemical and Electrochemical Properties of 2D Materials Kevin Jaouen, Florian Lebon, Bruno Jousselme, Stéphane Campidelli, Renaud Cornut, Vincent Derycke Optical microscopy based on anti-reflective coatings is a simple yet powerful characterization tool which notably allowed the first observation of graphene in 2004 and of other single-layered materials in the following years. Since then, the field of two-dimensional materials has developed rapidly both at the fundamental and applied levels. Yet, these ultrathin materials present inhomogeneities (edges, grain boundaries, defects, multilayers...) which strongly impact their intrinsic (physical, chemical) properties and the performances of the electronic, optoelectronic and energy-conversion devices. The use of local characterization techniques (spectroscopy mapping, scanning probe techniques...) is thus essential. Recently, D. Ausserré et al. introduced a new enhanced-contrast optical microscopy technique, named BALM (Backside Absorbing Layer Microscopy), based on ultrathin (2-5 nm) and strongly light-absorbing (metallic) anti-reflective layers. This talk aims at presenting the remarkable assets of this technique for the study of 2D materials. BALM notably allows observing mono-layered materials with very strong contrast even in the case of transparent ones such as graphene oxide [1]. The inverted microscope geometry allows imaging in solvents so that it is possible to investigate molecular adsorption dynamics on 2D materials in real-time and with extreme sensitivity.[1-2] With its wavelength sensitivity, it can also be used as a precise technique to determine the refractive index and extinction coefficient of TMDCs (MoS 2 , WS 2 ). But one of the main benefits of BALM comes from
En savoir plus

2 En savoir plus

Depth-resolved microscopy of cortical hemodynamics with optical coherence tomography

Depth-resolved microscopy of cortical hemodynamics with optical coherence tomography

Optical microscopy has been used to investigate the metabolic and hemodynamic responses to brain activation [1,2]. Optical methods can measure relative changes in cerebral blood flow, cerebral blood volume, and blood oxygenation with high spatiotemporal resolution. Optical intrinsic signal imaging (OISI) can provide highly sensitive measures of blood volume and oxygenation changes [3] but does not enable depth resolution. Scanning laser-Doppler [4] and laser speckle [5] imaging have been investigated for measurements of cerebral blood flow but cannot perform depth-resolved measurements. Two-photon microscopy [6] enables
En savoir plus

8 En savoir plus

Probing cytotoxicity of nanoparticles and organic compounds using scanning proton microscopy, scanning electron microscopy and fluorescence microscopy

Probing cytotoxicity of nanoparticles and organic compounds using scanning proton microscopy, scanning electron microscopy and fluorescence microscopy

4.3. Animal experiments of scavenge of inorganic particles Fe ions induce toxicity in lung tissues [18] and Fe 2 O 3 particles can be identified by optical microscopy, SPM and SEM. The histopa- thological changes in the lungs of different rat groups have been reported in the literature [18] . Black ferric oxide particles were found in alveolar but we could not ascertain the difference be- tween ferric oxide particles with other deposits including carbon and the scavenging process of such particles with time. Fe 2 O 3 par-

7 En savoir plus

Computational microscopy for sample analysis

Computational microscopy for sample analysis

Fluorescence EEMs of samples containing several fluorophores in a light-absorbing medium are generated based on Equation 2.2 in MATLAB. Since the shape of fluorescen[r]

44 En savoir plus

Quantitative measures of corneal transparency, derived from objective analysis of depth-resolved corneal images, demonstrated with full-field optical coherence tomographic microscopy

Quantitative measures of corneal transparency, derived from objective analysis of depth-resolved corneal images, demonstrated with full-field optical coherence tomographic microscopy

‡ Joint Senior Authors * kristina.irsch@inserm.fr Abstract Loss of corneal transparency, as occurs with various pathologies, infections, immune reac- tions, trauma, aging, and surgery, is a major cause of visual handicap worldwide. However, current means to assess corneal transparency are extremely limited and clinical and eye- bank practice usually involve a subjective and qualitative observation of opacities, some- times with comparison against an arbitrary grading scale, by means of slit-lamp biomicro- scopy. Here, we describe a novel objective optical data analysis-based method that enables quantifiable and standardized characterization of corneal transparency from depth-resolved corneal images, addressing the demand for such a means in both the laboratory and clinical ophthalmology setting. Our approach is based on a mathematical analysis of the acquired optical data with respect to the light attenuation from scattering processes in the corneal stroma. Applicable to any depth-resolved corneal imaging modality, it has been validated by means of full-field optical coherence tomographic microscopy (FF-OCT or FF-OCM). Spe- cifically, our results on ex-vivo corneal specimens illustrate that 1) in homogeneous tissues, characterized by an exponential light attenuation with stromal depth (z), the computation of the scattering mean-free path (l s ) from the rate of exponential decay allows quantification of the degree of transparency; 2) in heterogeneous tissues, identified by significant deviations from the normal exponential z -profile, a measure of exponential-decay model inadequacy (e.g., by computation of the Birge ratio) allows the estimation of severity of stromal heteroge- neity, and the associated depth-dependent variations around the average l s enables precise localization of the pathology.
En savoir plus

11 En savoir plus

Random Illumination Microscopy from Variance Images

Random Illumination Microscopy from Variance Images

P m,i [y m − x m ] 2 i ! is 50 dB. Then an additive Gaussian noise with a standard deviation displayed in Fig. 2E is added. The mean of all RIM images is shown in Fig. 2B. A red circle indicates the limit of the OTF support, the inner region being non- resolvable in the widefield image. Moreover, the background artefact is clearly visible and could lead to misinterpretations in real widefield fluorescence microscopy. The variance of all RIM images is shown in Fig. 2D. It contains smaller details inside the red circle. However, v x is not linearly related to

6 En savoir plus

Biomedical applications of holographic microscopy

Biomedical applications of holographic microscopy

The low-power imaging unit is equipped with a 1.4 A high-power 625-nm LED (Thor- labs) heat-sinked by a metal printed circuit board (PCB) and a custom machined aluminum holder. A 220-grit optical diffuser (DGUV10, Thorlabs) is positioned be- tween the LED and a 50 𝜇𝑚 pinhole (Thorlabs). Optical components are aligned by machined acrylonitrile butadiene styrene (ABS) mounts. Images are captured using a monochromatic 5 megapixel complementary metal-oxide-semiconductor (CMOS) im- age sensor (On-Semiconductor) mounted on a USB 2.0 interface board (The Imaging Source). The pixel size is 2.2 𝜇𝑚 and the field of view is 5.7 x 4.3 𝑚𝑚 2 . Image
En savoir plus

79 En savoir plus

Nano-contact microscopy of supracrystals

Nano-contact microscopy of supracrystals

Results: By exploring the evolution of both the force and tunnel current with respect to tip–sample separation, we arrive at the surprising finding that single nanocrystal resolution is readily obtained in tunnelling microscopy images acquired more than 1 nm into the repulsive (i.e., positive force) regime of the probe–nanocrystal interaction potential. Constant height force microscopy has been used to map tip–sample interactions in this regime, revealing inhomogeneities which arise from the convolution of the tip structure with the ligand distribution at the nanocrystal surface.
En savoir plus

9 En savoir plus

DNA Labeling at Electron Microscopy

DNA Labeling at Electron Microscopy

35. Roth J, Bendayan M, Carlemalm E et al (1981) Enhancement of structural preservation and immunocytochemical staining in low temperature embedded pancreatic tissue. J Histochem Cytochem 29:663–671. doi: 10.1177/29.5.6166664 36. Newman GR, Jasani B (1984) Post embedding immunoenzyme techniques. In: Polak JM, Varndell IM (eds) Immuno-labelling for electron microscopy. Elsevier, New York, NY, pp 53– 70

8 En savoir plus

Show all 2520 documents...