Pinhole (optics)

Wide-field microscopy image of a damaged 80 µm pinhole.

A pinhole is a small circular hole, as could be made with the point of a pin. In optics, pinholes with diameter between a few micrometers and a hundred micrometers are used as apertures in optical systems. Pinholes are commonly used to spatially filter a beam (such as a laser beam), where the small pinhole acts as a low-pass filter for spatial frequencies in the image plane of the beam.[1][2]

A small pinhole can act as a lens, focusing light. This effect is used in pinhole cameras. This effect is also used in pinhole occluders, which are used by ophthalmologists, orthoptists and optometrists to test visual acuity. The same principle has also been applied as an alternative to corrective lenses: a screen of pinholes is mounted on an eyeglass frame and worn as pinhole glasses.

References

  1. ↑ "Understanding Spatial Filters". Edmund Optics website. Edmund Optics. Retrieved 13 January 2014.
  2. ↑ "Spatial Filters". Newport website. Newport. Retrieved 13 January 2014.

See also

This article is issued from Wikipedia - version of the Thursday, March 05, 2015. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.