Pinhole (optics)
Apinholeis a small circular hole, as could be made with the point of apin.Inoptics,pinholes with diameter between a fewmicrometersand a hundred micrometers are used asaperturesin optical systems. Pinholes are commonly used tospatially filtera beam (such as alaserbeam), where the small pinhole acts as alow-pass filterforspatial frequenciesin theimage planeof the beam.[1][2]
A small pinhole can act as alens,focusing light. This effect is used inpinhole camerasandcamera obscura,and insolarigraphy.This effect is also used inpinhole occluders,which are used byophthalmologists,orthoptists,andoptometriststo testvisual acuity.The same principle has also been applied as an alternative tocorrective lenses:a screen of pinholes is mounted on aneyeglass frameand worn aspinhole glasses.
Besides pinholes made by the point of a pin, precision commercial pinholes are often made bylaser drillingthrough a thin foil.
References
[edit]- ^"Understanding Spatial Filters".Edmund Optics website.Edmund Optics.Retrieved13 January2014.
- ^"Spatial Filters".Newport website.Newport.Retrieved13 January2014.
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