Confocal Laser Scanning Microscopy (CLSM)


Prof. Dr. Gunther Wittstock
Group Leader

Group members

+49 (0) 441 798 3970

+49 (0) 441 798 3979

Mailing Address

University of Oldenburg
School of Mathematics
   and Science
Institute of Chemistry
Wittstock Group
D-26111 Oldenburg


University of Oldenburg
Campus Wechloy
Carl-von-Ossietzky Street 9-11
Building W3, 1st floor
D-26129 Oldenburg

How to find us

Confocal Laser Scanning Microscopy (CLSM)


Leica TCS SP2; 8 laser lines for excitations, acousto-optical bveam splitter (AOBS) allows adaptation to different fluoresence dyes without change of filter sets, works in reflection and fluorescence mode. An emission spectrometer is available at the instrument.

Operation Principle

Confocal laser microscopy (CLSM) uses a laser to produce point-probing raster scanning, yielding images with very high contrast in the third dimension. A small aperture at the secondary focus of the objective lens narrows the depth of focus and obstructs most of the light reflected from out-of-focus objects. CLSM is a valuable tool for obtaining high resolution images and 3D reconstructions from surfaces. The key feature of confocal microscopy is its ability to produce blur-free images of thick specimens at various depths. The confocal principle is illustrated schematically below. To image the specimen point by point, a collimated, polarized laser beam is deflected stepwise in the x- and y-direction by a scanning unit before it is reflected by a beam splitter so as to pass through the objective lens of the microscope, and focused onto the specimen. The emitted, longer-wavelength fluorescent light collected by the objective lens passes through the beam splitter and is focused into a small pinhole (i.e., the confocal aperture) to eliminate all the out-of-focus light, i.e., all light coming from regions of the specimen above or below the plane of focus.

(Changed: 20 Jan 2023)  | 
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