Spatial resolution, of the microscope

A principal advantage of the Raman microprobe is that the optics are those of a conventional light microscope a wide variety of special-purpose objectives developed for materials and biological microscopy are available. The Raman microprobe also offers the advantage of fluorescence reduction owing to the high spatial resolution of the microscope if a region of low fluorescence can be chosen for observation. 

Micromineralogical studies of these coal wastes were performed by electron microscopy coupled with energy dispersive spectrometry. Because this technique observes such a small fraction of the sample at any one time, the results must be interpreted carefully. Nevertheless, one can perform elemental analyses while retaining the spatial resolution of the microscope. This is difficult, if not impossible, with other techniques. These studies confirmed that most of the trace elements are associated with various types of clays. In addition, the trace... 

The spatial resolution of the microscope is determined by the wavelength of the radiation, X, and the numerical aperture (NA) of the Cassegrain. Less fundamentally, spatial resolution is also limited by the SNR that can be achieved when the size of the aperture is very small. The NA is the sine of the acceptance half-angle at the sample. At the beginning of this chapter it was stated that the diffraction-limited spatial resolution is approximately equal to the wavelength, X. More accurately, it is given by... 

Plenary 8. J Grave et al, e-mail address J.Greve tn.utwente.nl (RS). Confocal direct unaging Raman microscope (CDIRM) for probing of the human eye lens. High spatial resolution of the distribution of water and cholesterol in lenses. 

The spatial resolution of the Raman microprobe is about an order of magnitude better than that obtainable using an infrared microscope. Measurement times, typically of a few seconds, are the same as for other Raman spectrographs. To avoid burning samples, low (5—50-mW) power lasers are employed. 

A common feature of anorthite crystals in Allende Type B inclusions is large variations (up to a factor of -v 5) in Mg content on a scale of 10 to 50 pm. (Mg variability and its correlation with Na content and cathodoluminescence color are discussed extensively in [12].) Guided by cathodoluminescence micrographs, we used the microscopic spatial resolution of the ion-probe to measure the Mg isotopic composition at several points with distinct 27Al/24Mg ratios within individual crystals from TS-21 and TS-23. Data from each individual crystal define an... 

The microscopic spatial resolution of the ion probe enabled us to measure the isotopic composition at several points within individual crystals and these ion probe data establish the first single crystal isochron for areas with distinct 27Al/24Mg ratios. The Mg isotopic pattern within each B1 and B2 anorthite is individually consistent with a single (26A1/27A1)q ratio, suggesting... 

FIGURE 3.4 Performance of the fluorescence up-conversion microscope, (a) Evaluation of the time-resolution with the 100 x objective lens , up-converted fluorescence -F-, the first derivative. By the fitting analysis, the time-resolution of the microscope was evaluated as 520 fs. (b) Evaluation of the transverse (XY) spatial resolution with the 100 x objective lens. A CCD image of the excitation pulses (inset) and the beam profile along the lateral (X) direction. By the fitting analysis, the transverse resolution was evaluated as 0.34 pm. (c d) Evaluation of the axial (Z) spatial resolution with the 100 x objective lens , up-converted fluorescence -I-, the first derivative. By fitting analysis on the first derivative coefficient, the axial resolution was evaluated as 1.1 pm with the 50 pm pinhole (c) and 5.3 pm without pinhole (d). (Rhodamine B, 2 x 10" mol dm in methanol, 600 nm.) (Erom Eujino, T. and Tahara, T., Appl Phys. B 79 145-151, 2004. Used with permission.)... 

In section IID, we introduced the utilization of chemical enhancement effect for higher sensitivity in TERS. Here, it should be pointed out that in addition to electromagnetic enhancement and chemical enhancement effects, physical deformation induced by tip-applied force showed extra enhancement effect in TERS on carbon materials such as SWNTs and fullerene molecules (Yano et al. 2005, 2006 Verma et al. 2006). This tip-pressurized effect is a unique feature of TERS and not observable in SERS. Since the spatial resolution of TERS with tip-pressurized effect is determined by the size of the very end of the metallic tip that has direct contact with the molecules, this is a very promising approach to improve the spatial resolution of the near-field microscope. 

For this type of superresolution optical microscope, experiments have shown that it is possible to have spatial resolutions of the order of X/50. It is believed that the technique can be improved so to allow spatial resolutions of over X/100. 

The magnification attended in the experiment with the photoelectron microscope was M = 10s, and the spatial resolution was around 30 nm, which proved sufficient for the visualization of individual color centers in a LiF crystal with the concentration of such centers less than 10l7cm 3. The results obtained in Ref. 9 may be considered the first successful implementation of laser resonance photoelectron microscopy possessing both subwavelength spatial resolution and chemical selectivity (spectral resolution). It will be necessary to increase the spatial resolution of the technique by approximately an order of magnitude and substantially improve its spectral resolution by effecting resonance multistep photoionization by means of tunable ultrashort laser pulses. 

Raman microspectroscopy results from coupling of an optical microscope to a Raman spectrometer. The high spatial resolution of the confocal Raman microspectrometry allows the characterization of the structure of food sample at a micrometer scale. The principle of this imaging technique is based on specific vibration bands as markers of Raman technique, which permit the reconstruction of spectral images by surface scanning on an area. 

Raman microscopes are more commonly used for materials characterization than other Raman instruments. Raman microscopes are able to examine microscopic areas of materials by focusing the laser beam down to the micrometer level without much sample preparation as long as a surface of the sample is free from contamination. This technique should be referred to as Raman microspectroscopy because Raman microscopy is not mainly used for imaging purposes, similar to FUR microspectroscopy. An important difference between Raman micro-and FUR microspectroscopies is their spatial resolution. The spatial resolution of the Raman microscope is at least one order of magnitude higher than the FTIR microscope. 

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