Spatial filter

Air filters are made of a micro- lens and a diaphragm. The panel typically has a very small hole diameters (about 20 microns ) and is therefore also called pinhole ( pinhole ).

Spatial filter can be used, for example, in holography, for example to filter laser light. Thus, interference effects are eliminated, which can be caused by dirty lenses and dust particles in the air.

One can compare this with a microscope at the effect. Here is the focal plane manipulates behind the lens with a pinhole, so go higher diffraction orders and therefore information will be lost. But the picture is then featureless and uniformly bright

• Optical component