Aberration, optical
The term optical aberration sums up all deviations in the image forming properties of lenses and optical systems. These deviations can be differentiated into chromatic aberrations and monochromatic aberrations, the later being subdivided...

Ablation
The controlled removal of material by vaporisation or molecular fragmentation using high energy radiation is called ablation.

Achromatic objectives
Achromats are objectives corrected for chromatic aberration in the range of red and blue light (656nm and 486nm). Additionally they have ...

Acousto-optical tunable filter (AOTF)
A filtering device employed to modulate the wavelength and amplitude of illuminating laser light in the latest generation of confocal microscopes. The AOTF utilises sound waves to modulate the wavelength or intensity of ...

Aequorin
Aequorin, isolated from the jellyfish Aequorea victoria, is a complex of the luciferin derivative coelenterazine, molecular oxygen and the apoprotein. If activated by Ca2+ binding it catalyses the oxidation of coelenterazine to the...

Airy disc
A beam of light is diffracted when passing an aperture. If the aperture is a circular pinhole a diffraction pattern can be observed consisting of a central disc of light surrounded by concentric light circles. The size of the central disc is ...

Amplitude
The term Amplitude describes the magnitude of oscillation of a wave. When describing the properties of electromagnetic radiation in the range of visible light, changes in the amplitude of a light wave are perceived as changes in ...

Asbestos fibers
Specimens are commonly screened for asbestos fibers using scanning electron microscopy and x-ray microanalysis. Polarising microscopy provides a quicker and easier alternative that can be utilised to distinguish between asbestos and other fibers ...

Astigmatism
see Aberration, optical