Probing Biological Samples with Near-Field Optics

2000 ◽  
Vol 6 (S2) ◽  
pp. 826-827
Author(s):  
Sarah A. Vickery ◽  
Christopher W. Hollars ◽  
Robert C. Dunn
Keyword(s):  
Optical Microscopy ◽  
Light Source ◽  
Electric Fields ◽  
Spatial Resolution ◽  
Single Molecule ◽  
Lipid Membranes ◽  
Near Field ◽  
Level Structure ◽  
Sample Surface ◽  
Model Lipid Membranes

Near-field scanning optical microscopy (NSOM) is an emerging optical technique capable of probing samples at the nanometric level. With the NSOM technique, high spatial resolution is achieved by scanning a small light source (or collector) close to a sample surface. The light source is usually formed with special fiber optic probes that funnel light down to an aperture that is smaller than the optical wavelength. By positioning the aperture close to a sample, the emerging radiation is forced to interact with the sample before diffracting out. Therefore, the spatial resolution in NSOM is only limited by the size of the aperture and its proximity to the sample, and not the wavelength of the light as in conventional optical microscopy.Recently, we have been using the single molecule detection limits combined with the unique nature of the electric fields present near the NSOM tip aperture to probe molecular level structure in model lipid membranes.

Spectral-Type Probe with λ/40 Resolution for Near-Field Optical Microscopy Systems

2013 ◽  
Vol 677 ◽  
pp. 373-378
Author(s):  
Yuri N. Kulchin ◽  
Oleg B. Vitrik ◽  
Aleksandr A. Kuchmizhak
Keyword(s):  
Optical Microscopy ◽  
Light Source ◽  
Spatial Resolution ◽  
Spectral Type ◽  
Near Field ◽  
Fabrication Process ◽  
Fabry Perot ◽  
Evanescent Light

We studied numerically and experimentally the ability to develop a new probe based on fiber Fabry-Perot interferometer with an evanescent light source protruding directly toward the sample. It was shown that such probe provides a spatial resolution of no worse than ~λ/40 for λ=1550 nm. The fabrication process of the probe is described in detail.

Tapping Mode Near-Field Scanning Optical Microscopy of Molecular Crystals and Thin Films

1999 ◽  
Vol 5 (S2) ◽  
pp. 994-995
Author(s):  
C. Daniel Frisbie ◽  
Andrey Kosterin ◽  
Helena Stadniychuk
Keyword(s):  
Optical Microscopy ◽  
Spatial Resolution ◽  
Laser Light ◽  
Near Field ◽  
Sample Surface ◽  
Reflected Light ◽  
Surface Laser ◽  
Scanning Optical Microscopy ◽  
Diffraction Effects ◽  
Near Field Scanning

The diffraction of visible light limits the spatial resolution in conventional optical microscopy to about 200-300 nm. In near-field scanning optical microscopy (NSOM), resolution is improved by bringing the light source, such as the end of an optical fiber, very close to the sample surface. Laser light coupled into the opposite end of the fiber propagates down the fiber core and is emitted from the aperture of the tip. When the sample is in the near-field(roughly within one tip diameter of the end of the tip), the spatial resolution is essentially equal to the diameter of the aperture at the end of the tip and is not determined by diffraction effects. Two-dimensional imaging is accomplished by raster-scanning the sample underneath the fiber tip and collecting transmitted or reflected light at a photodetector.

Photoreflectance Near-Field Scanning Optical Microscopy

1999 ◽  
Vol 588 ◽  
Author(s):  
Charles Paulson ◽  
Brian Hawkins ◽  
Jingxi Sun ◽  
Arthur B. Ellis ◽  
Leon Mccaughan ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Electric Fields ◽  
Spatial Resolution ◽  
High Intensity ◽  
Near Field ◽  
And Topology ◽  
Wavelength Resolution ◽  
Scanning Optical Microscopy ◽  
Near Field Scanning ◽  
Sub Wavelength

AbstractA novel Near-field Scanning Optical Microscopy (NSOM) technique is used to obtain simultaneous topology, photoluminescence and photoreflectance (PR) spectra. PR spectra from GaAs surfaces were obtained and the local electric fields were calculated. Sub-wavelength resolution is expected for this technique and achieved for PL and topology measurements. Photovoltages, resulting from the high intensity of light at the NSOM tip, can limit the spatial resolution of the electric field determination.

Alterations of Single Molecule Fluorescence Lifetimes in Near-Field Optical Microscopy

Science ◽  
1994 ◽  
Vol 265 (5170) ◽  
pp. 364-367 ◽  
Author(s):  
W. P. Ambrose ◽  
P. M. Goodwin ◽  
R. A. Keller ◽  
J. C. Martin
Keyword(s):  
Optical Microscopy ◽  
Single Molecule ◽  
Near Field ◽  
Fluorescence Lifetimes ◽  
Single Molecule Fluorescence

Development of a Combined Scanning Ion-Conductance and Nearfield Optical Microscope to Image Living Cells

1999 ◽  
Vol 5 (S2) ◽  
pp. 976-977
Author(s):  
M. Raval ◽  
D. Klenerman ◽  
T. Rayment ◽  
Y. Korchev ◽  
M. Lab
Keyword(s):  
Optical Microscopy ◽  
Biological Samples ◽  
Near Field ◽  
Sample Surface ◽  
Optical Microscope ◽  
Ion Conductance ◽  
Simultaneous Generation ◽  
Simple Arrangement ◽  
Wavelength Resolution ◽  
Sub Wavelength

It is important to be able to image biological samples in a manner that is non-invasive and allows the sample to retain its functionality during imaging.A member of the SPM (scanning probe microscopy) family, SNOM (scanning near-field optical microscopy), has emerged as a technique that allows optical and topographic imaging of biological samples whilst satisfying the above stated criteria. The basic operating principle of SNOM is as follows. Light is coupled down a fibre-optic probe with an output aperture of sub-wavelength dimensions. The probe is then scanned over the sample surface from a distance that is approximately equal to the size of its aperture. By this apparently simple arrangement, the diffraction limit posed by conventional optical microscopy is overcome and simultaneous generation of optical and topographic images of sub-wavelength resolution is made possible. Spatial resolution values of lOOnm in air and 60nm in liquid[1,2] are achievable with SNOM.

ELECTROFUSION OF MODEL LIPID MEMBRANES VIEWED WITH HIGH TEMPORAL RESOLUTION

2006 ◽  
Vol 01 (04) ◽  
pp. 387-400 ◽  
Author(s):  
KARIN. A. RISKE ◽  
NATALYA BEZLYEPKINA ◽  
REINHARD LIPOWSKY ◽  
RUMIANA DIMOVA
Keyword(s):  
Electric Fields ◽  
Temporal Resolution ◽  
Lipid Membranes ◽  
Cell Biology ◽  
Digital Camera ◽  
Extensive Study ◽  
High Temporal Resolution ◽  
Giant Vesicles ◽  
Model Lipid Membranes ◽  
Millisecond Time Scale

The interaction of electric fields with lipid membranes and cells has been extensively studied in the last decades. The phenomena of electroporation and electrofusion are of particular interest because of their widespread use in cell biology and biotechnology. Giant vesicles, being of cell size and convenient for microscopy observations, are the simplest model of the cell membrane. However, optical microscopy observation of effects caused by electric DC pulses on giant vesicles is difficult because of the short duration of the pulse. Recently this difficulty has been overcome in our lab. Using a digital camera with high temporal resolution, we were able to access vesicle fusion dynamics on a sub-millisecond time scale. In this report, we present some observations on electrodeformation and –poration of single vesicles followed by an extensive study on the electrofusion of vesicle couples. Finally, we suggest an attractive approach for creating multidomain vesicles using electrofusion and present some preliminary results on the effect of membrane stiffness on the fusion dynamics.

Near-Field Optical Probe Based on the Fiber Fabry-Perot Interferometer with Protruding Evanescent Light Source

2014 ◽  
Vol 213 ◽  
pp. 204-209
Author(s):  
Aleksandr A. Kuchmizhak ◽  
Oleg B. Vitrik ◽  
Yuri N. Kulchin
Keyword(s):  
Light Source ◽  
Spatial Resolution ◽  
Near Field ◽  
Optical Probe ◽  
Fabrication Process ◽  
Fabry Perot ◽  
Evanescent Light

We studied numerically and experimentally the possibility of the development of a novel probe based on the fiber Fabry-Perot interferometer with an evanescent light source protruding directly toward the sample. It was shown that such probe provides a spatial resolution ~λ/40 for λ=1550 nm. The fabrication process of such a probe is described in detail.

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