Lens arrangement

Abstract

A lens arrangement suitable for looking through small holes is provided in which no conventional integral physical lens stop is required. The lens arrangement is relatively insensitive to its position, meaning that it may be set back behind the hole reducing the risk of detection and allowing rapid installation.

Description

technical field [0001] The present invention relates to optical lenses, and more particularly to lenses for camera systems. The invention is particularly suitable for use in the field of covert surveillance cameras using very small "pinhole" camera lenses. Background technique [0002] Pinhole lenses are useful because of their small size, with typical lenses measuring just a few millimeters in diameter, making them immune to detection. A pinhole camera is usually hidden behind a wall or other obstruction in which a small hole (called a pinhole) is drilled to enable covert viewing and monitoring of a scene. In this specification, a pinhole is defined as a hole with a diameter of 2 mm or less. A disadvantage of these known lenses is that a physical stop is required to limit the beam of light that can pass through it to strike an image capture unit (eg film or sensor or human eye). For the aforementioned pinhole lenses, the physical aperture usually has to protrude into the...

AI Technical Summary

Problems solved by technology

A disadvantage of these known lenses is that a physical stop is required to limit the beam of light that can pass through it to impinge on the image capture unit (e.g. film or sensor or human eye)

For the aforementioned pinhole lenses, the physical aperture usually has to protrude into the hole in the wall to provide acceptable image quality and reduce vignetting, which significantly increases the risk of detection (see figure 1 )

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