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Difference between revisions of "Light microscopy"
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This article examines '''light microscopy'''. | [[Image:Optical microscope nikon alphaphot +.jpg|thumb|250px|A light microscope.]] | ||
This article examines '''light microscopy''', abbreviated '''LM'''. | |||
==Resolution== | ==Resolution== | ||
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==Depth of field== | ==Depth of field== | ||
*Abbreviated ''DOF''. | *Abbreviated ''DOF''. | ||
*DOF depends on the aperature (small is better). | |||
Relation to other parameters:<ref name=grayfield_dof>URL: [http://www.grayfieldoptical.com/depth_of_fieldfocus.html http://www.grayfieldoptical.com/depth_of_fieldfocus.html]. Accessed on: 27 May 2011.</ref> | |||
*Inverse relationship with resolution and brightness. | |||
*Related to contrast. | |||
*High magnification --> smaller depth of field. | |||
===Formula=== | |||
<math>DOF = { \lambda_o n \over NA^2}+{ n \over M \cdot NA } e | <math>DOF = { \lambda_o n \over NA^2}+{ n \over M \cdot NA } e | ||
</math>.<ref>URL: [http://www.microscopyu.com/articles/formulas/formulasfielddepth.html http://www.microscopyu.com/articles/formulas/formulasfielddepth.html]. Accessed on: 27 May 2011.</ref> | </math>.<ref>URL: [http://www.microscopyu.com/articles/formulas/formulasfielddepth.html http://www.microscopyu.com/articles/formulas/formulasfielddepth.html]. Accessed on: 27 May 2011.</ref> | ||
== | Where: | ||
*<math>\lambda_o</math> = illuminating light wavelength. | |||
*n = refractive index of the medium, 1.0 for air. | |||
*NA = numerical aperature (objective). | |||
*M = magnification. | |||
*e = resolution. | |||
===Increasing the DOF=== | |||
*DOF can be increased by ''focus stacking''. | |||
Software: | |||
*[http://hugin.sourceforge.net/ Hugin (sourceforge.net)] - does ''focus stacking'' and ''stitching''. | |||
Image: | |||
*[http://commons.wikimedia.org/wiki/File:Focus_stacking_Tachinid_fly.jpg Example of focus stacking (WC)]. | |||
==Köhler illumination== | |||
===Rationale=== | ===Rationale=== | ||
* | *Even light distribution (avoid [[vignetting]]). | ||
===Procedure=== | ===Procedure=== | ||
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*[[Microphotography]]. | *[[Microphotography]]. | ||
*[[Electron microscopy]]. | *[[Electron microscopy]]. | ||
*[[Polarization of light]]. | |||
==References== | ==References== | ||