Optical peephole device insertable in thick walls for panoramic viewing therethrough

Claim 1

An optical device insertable through a peephole in the wall of a chamber such as a bank vault having a thickness greater than about 10 centimeters, making it possible for an observer to obtain a panoramic view of the interior and of the objects dispersed therein; said device being constituted by an optical system formed by three lens assemblies disposed successively in cooperative relation along a common central optical axis in said peephole; said system comprising: A. a wide-angle first lens assembly placed in the peephole adjacent the chamber side thereof to create a virtual image of the interior and the objects dispersed therein at a position in front of this assembly; B. A convergent second lens assembly placed in the peephole behind the first assembly and having a length approaching the thickness of the wall, said second assembly having an entry and exit to optically derive from the virtual image developed by the first assembly a final image which is positioned adjacent said exit; and C. an accommodation third lens assembly placed in the peephole behind the second assembly and accessible to the observer to permit an observer's eye located behind it to see the final image developed by the second assembly at an apparent diameter which is essentially equal to that at which the virtual image is seen from the entry of the second assembly whereby objects in the interior may be seen in a manner essentially equivalent in image quality to that observable when made directly with the first and third assemblies; D. said first assembly comprises a doublet constituted by a thick edged meniscus whose front face has a radius of curvature that is large relative to that of its rear face which has a hemispherical formation, and a double-concave lens behind the meniscus having radii and a diameter substantially greater than those of the rear face of the meniscus, said second assembly comprises a series of five identical lenses, the successive distance between these lenses being slightly less than twice their focal length, the first lens being the entry and the fifth lens being the exit of the second assembly.