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1  Principles of Confocal Scanning

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1.1     Laser Scanning Confocal Microscope

Laser light source - mirror scanning - emission filter - dichroic mirror - barrier filter - stage galvanometer - pin hole - PMT - Analogue to digital converter - frame store - computer control - computer storage - i/o devices.

Airy_disc_Illustr_brief_quarter.jpg (9997 bytes)1.2   What Are Airy Disks?

As with standard fluorescence (wide field) microscopy, Airy disks may be seen around small sub-resolution point objects.  Such disks or rings may be imaged in confocal scanning mode to reveal sharp rings.  These Airy disks have a characteristic size and shape that is dependent on the numerical aperture, N.A. and overall magnification of the system.

The figures shows a series of Airy disks.  Each panel shows the image obtained further away from the focal plane.  Top left panel shows the 0.5um fluorescent bead in focus.  Note that the disk get larger and dimmer away from the focal plane.  Airy disk units are a convenient way to normalize confocal pin hole size.  A confocal pin hole size of one Airy disk unit will let 95% of in focus light pass to the detector.

 

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NEXT ---> 1.3   Objective Magnification & Numerical Aperture

Last updated 10/24/06


Icon_Inverted_Laser.GIF (1500 bytes) Icon_book_white.gif (1143 bytes) 1998-2003 Michael Chua, Cell & Molecular Physiology, UNC.  All rights reserved. 
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