Spatial filter (optics)

Structure of a room filter with lens and diaphragm

Spatial filters consist of a micro lens and a diaphragm . The aperture typically has a very small hole diameter (approx. 20 μm) and is therefore also called a pinhole .

Room filters can be z. B. for filtering laser light z. B. use in holography . This eliminates interference phenomena that can arise from dirty lenses or dust particles in the air.