Search results for "MICROSCOPE"
showing 10 items of 1412 documents
First images obtained in the near infrared spectrum with the photon scanning tunneling microscope
1993
Abstract First images obtained in the near infrared spectrum with a photon scanning tunneling microscope are presented. The intensity of the light collected by the fibertip, at λ = 1.3 λm , which is a function of the separation between the tip and the sample surface is in agreement with that predicted by the theory. Images of quartz and silicon oxide are presented and the latter is compared with that obtained by an atomic force microscope.
Microscope system with on axis programmable Fourier transform filtering
2017
Abstract We propose an on-axis microscope optical system to implement programmable optical Fourier transform image processing operations, taking advantage of phase and polarization modulation of a liquid crystal on silicon (LCOS) display. We use a Hamamatsu spatial light modulator (SLM), free of flickering, which therefore can be tuned to fully eliminate the zero order component of the encoded diffractive filter. This allows the realization of filtering operation on axis (as opposed to other systems in the literature that require operating off axis), therefore making use of the full space bandwidth provided by the SLM. The system is first demonstrated by implementing different optical proce…
One-dimensional wavelength multiplexed microscope without objective lens
2009
A new approach aimed to achieve microscopic imaging without objective lenses and based on wavelength multiplexing of the spatial object information is presented. The proposed method is used to develop, construct and experimentally validate a new type of optical microscope having no objective lens and no numerical reconstruction algorithms to allow imaging process. In order to extract the collected spatial information we use a spectrometer as part of our microscope system. Preliminary results are presented while considering two different types of one-dimensional (1-D) objects.
Effects of various hygiene procedures on the surface characteristics of titanium abutments.
1996
The use of cleaning instruments on titanium implants may cause undesired surface alterations. In a qualitative and quantitative assessment of these alterations, 5 titanium implant abutments were treated with a steel curet, a prototype pure titanium curet, an air abrasive polishing system, and an ultrasonic system. Custom-made polymer templates, used to secure the curet to a vertical guide bar and a spring scale to maintain a constant instrument pressure, guaranteed a standardized procedure and reproducible results. The ultrasonic and the air abrasive polishing method were also standardized. Evaluation by scanning electron microscopy (SEM) revealed surface alterations for all instruments and…
Two-photon light-sheet microscopy for high-speed whole-brain functional imaging of zebrafish neuronal physiology and pathology
2020
We present the development of a custom-made two-photon light-sheet microscope optimized for high-speed (5 Hz) volumetric imaging of zebrafish larval brain for the analysis of neuronal physiological and pathological activity. High-speed volumetric two-photon light-sheet microscopy is challenging to achieve, due to constrains on the signal-to-noise ratio. To maximize this parameter, we optimized our setup for high peak power of excitation light, while finely controlling its polarization, and we implemented remote scanning of the focal plane to record without disturbing the sample. Two-photon illumination is advantageous for zebrafish larva studies since infra-red excitation does not induce a …
Investigations of the emission properties of single CdS-nanocrystallites
1997
Semiconductor nanocrystallites (NCs) with a radius in the range of the bulk exciton radius exhibit a strong quantum size effect. We investigated CdS-NCs, that were spin coated on a glass cover slip, with a low temperature confocal microscope. At low coverage we could image the fluorescence light from single NCs. The typical emission spectra of single NCs show four peaks. Besides the main peak related to near bandgap recombination, up to two LO-phonon satellites and one blue shifted peak were observed. It could be shown that the absorption can be polarization dependent. From the images as well as from the intensity autocorrelation function it could be concluded that the fluorescence emission…
Theory of Near‐field Optical Imaging with a Single Molecule as Light Source
2002
Scanning near-field optical microscopes (SNOM) illuminate a sample in the very near-field using a nanometer sized tip. Ideally, the light source should be point-like and many efforts have been made to optimize tip efficiency (see, for example, the article of Heimel et al in this issue). Very recently, Sandoghdar et al have realized a molecular probe tip in which a terrylene molecule inserted in a paraterphenyl microcrystal is attached at the extremity of the probe tip [1]. The excited molecule behaves as a point-like light source which is raster scanned over an aluminium patterned structure. We propose here an analysis of this experiment based on the field-susceptibility formalism (also cal…
Recent Advances in Digital Holographic Microscopy
2018
In digital holographic microscopy (DHM) a hologram is captured in the image space provided by a microscope. The transfer of the phase and amplitude structure in the original sample to the hologram is in fact strongly affected by the use of the imaging microscope. A big research effort has been devoted to correct these distortions both by numerical and optical compensation. In this contribution, we present several proposals to improve the performance of classical DHM architectures by an a priori approach to compensate physically these perturbations. Experimental results are also presented to validate the proposed techniques.
Fourier-domain lightfield microscopy: a new paradigm in 3D microscopy
2020
Recently, integral (also known as lightfield or plenoptic) imaging concept has been applied successfully to microscopy. The main advantage of lightfield microscopy when compared with conventional 3D imaging techniques is that it offers the possibility of capturing the 3D information of the sample after a single shot. However, integral microscopy is now facing many challenges, like improving the resolution and depth of field of the reconstructed specimens or the development and optimization of specially-adapted reconstruction algorithms. This contribution is devoted to review a new paradigm in lightfield microscopy, namely, the Fourier-domain integral microscope (FiMic), that improves the ca…
Robust Depth Estimation for Light Field Microscopy
2019
Light field technologies have seen a rise in recent years and microscopy is a field where such technology has had a deep impact. The possibility to provide spatial and angular information at the same time and in a single shot brings several advantages and allows for new applications. A common goal in these applications is the calculation of a depth map to reconstruct the three-dimensional geometry of the scene. Many approaches are applicable, but most of them cannot achieve high accuracy because of the nature of such images: biological samples are usually poor in features and do not exhibit sharp colors like natural scene. Due to such conditions, standard approaches result in noisy depth ma…