Confocal laser scanning microscope

A Confocal laser scanning microscope is derived from the traditional optical microscope but its light source is a laser which scans the observed object point by point. In its "reflection" configuration, it uses a half-silvered mirror which reflects the beam from the object towards a detector. The detector can thus measure the luminous intensity of each point and store it in a computer.

Obtaining 3D images

Once the x-y scanning has been completed and a two-dimensional image obtained, the support containing the object is moved by an increment dz and the scanning recommences. Thus "slices" are memorised and can then be processed by a computer to obtain three-dimensional images of the object.

The principle of confocality

To successfully achieve this, when the confocal laser scanning microscope is set to a height z it must not be influenced by the layers above and below. To do this a diaphragm is placed in front of the detector in the conjugate focal plane of the objective (hence the name "confocal"). Thus, only the light from the focal plane can reach the detector.