Peephole

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title: "Peephole" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["door-furniture", "security-technology"] description: "Small, round opening through a door" topic_path: "general/door-furniture" source: "https://en.wikipedia.org/wiki/Peephole" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Small, round opening through a door ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/4/48/Peephole.jpg" caption="View through a peephole"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/3/38/Barack_Obama_looking_through_the_Oval_Office_door_peephole.jpg" caption="[[Barack Obama]] looking through the [[Oval Office]] door peephole"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/c/c6/Gate_at_Vaxholm_Fortress_(41800).jpg" caption="Door viewer in the gate of [[Vaxholm Fortress"] ::

A modern peephole, peekhole, spyhole, doorhole, magic eye, magic mirror or door viewer is a small, round opening through a door from which a viewer on the inside of a dwelling may "peek" to see directly outside the door. The lenses are made and arranged in such a way that viewing is only possible in one direction. The opening is typically no larger than the diameter of a dime (0.7 in).

In a door, usually for apartments or hotel rooms, a peephole enables one to see outside without opening the door nor revealing one's presence. Glass peepholes are often fitted with a fisheye lens to allow a wider field of view from the inside.

Preventing inside viewability

Simple peepholes may allow people outside to see inside. A fisheye lens offers little visibility from the outside, but that can be defeated using a peephole reverser. Some peepholes have a shutter that falls down on the hole when nobody inside is holding it. Digital peepholes have a camera outside and an LCD screen inside, without any information going from the inside to the outside.

Another design to prevent people outside from seeing in involves the outside-facing lens projecting an image onto a semi-opaque frosted or ground glass screen. An inside viewer can see the other side of the door from an arm's length away, rather than by peering through a small hole, while the frosted glass finish makes it impossible for someone to look through from the outside. There are drawbacks to the projection method: the area to be viewed must be well lit, and installation requires a much larger hole in the door than a traditional peephole.

References

References

1. (July 1950). "Peephole Is One Way Viewer".

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::