Microscopy & Resolution

8/2/2019 Microscopy & Resolution

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OU NanoLab/NSF NUE/Bumm & Johnson

Microscopy & Resolution

Magnification: Image size/Object sizeResolution: The fineness of detail that can be

distinguished in an image.

Highest Typical ResolutionOptical Microscope ~200 nmElectron Microscope ~0.1 nm


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Definitions

Acceptance angle

Numerical ApertureNA = nsin

Rayleigh resolution criterion for a circularaperturex= 0.61 /NA


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OPTICAL MICROSCOPES

Image construction for a simple biconvex lens


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Rayleigh criterion for resolution

www.microscopy.fsu.edu ; www.imb-jena.de

See more interactive tutorials at www.microscopy.fsu.edu

Numerical Aperature Resolution Rayleigh Criterion
http://www.microscopy.fsu.edu/primer/anatomy/anatomyjava.htmlhttp://www.microscopy.fsu.edu/primer/java/nuaperture/index.htmlhttp://www.microscopy.fsu.edu/primer/java/imageformation/airyna/index.htmlhttp://www.microscopy.fsu.edu/primer/java/imageformation/rayleighdisks/index.htmlhttp://www.microscopy.fsu.edu/primer/java/imageformation/rayleighdisks/index.htmlhttp://www.microscopy.fsu.edu/primer/java/imageformation/airyna/index.htmlhttp://www.microscopy.fsu.edu/primer/java/nuaperture/index.htmlhttp://www.microscopy.fsu.edu/primer/anatomy/anatomyjava.html


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ComparisonBright-Field

Dark-

Field Fullapertureisilluminated

A centralobstruction blocksthe central cone.


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OU NanoLab/NSF NUE/Bumm & Johnson www.microscopy.fsu.edu

Dark-Field

Optical Microscopy

A central obstructionblocks the central cone.

The sample is onlyilluminated by the

marginal rays.

These marginal rays mustbe at angles too large forthe objective lens tocollect.

Only light scattered by theobject is collected by the

lens.


7/12OU NanoLab/NSF NUE/Bumm & Johnson www.microscopy.fsu.edu

Dark-Field

Optical

Microscopy


8/12OU NanoLab/NSF NUE/Bumm & Johnson

THE ELECTRON MICROSCOPE

The wavelength of the electron can be tuned by changing the

accelerating voltage.

de Broglie : = h/mv: wavelength associated with the particleh: Planks constant 6.6310-34 Js;

mv: momentum of the particleme= 9.110

-31 kg; e= 1.610-19 coulomb

P.E eV = mv2 = h/(2meV) = 12.3/V (for Vin KV, in )Vof 60 kV, = 0.05 x~ 2.5 Microscopes using electrons as illuminating radiation

TEM & SEM



Components of the TEM

1. Electron Gun: Filament, Anode/Cathode

2. Condenser lens system and its apertures

3. Specimen chamber

4. Objective lens and apertures

5. Projective lens system and apertures

6. Correctional facilities (Chromatic, Spherical, Astigmatism)

7. Desk consol with CRTs and camera

Transformers: 20-100 kV; Vacuum pumps: 10-6 10-10 Torr



Schematic of E Gun & EM lens

Magnification: 10,000 100,000; Resolution: 1 - 0.2 nm

www.udel.edu



TEM IMAGES

www.udel.edu ; www.nano-lab. com ; www.thermo.com

Documents

Microscopy & Resolution