Device and method for monitoring the presence of an object in space

摘要

An optically transparent cylinder having a hemispherical cavity at one end thereof and containing at least one light source and one light detector inside the hemispherical cavity utilizes the prismatic effect of the cylinder to locate an object in space. The light source and detector are located on a disk whose insertion depth into the cavity and tilt angle inside the cavity can be varied to control the sharpness, width and direction of the conical beam output from the cylinder, the beam searching the space for the location of the desired object.