A light localizer for use at large distances from a radiation source.

In the superconducting cyclotron used for neutron therapy at Harper Hospital, space limitations prevented the use of a simple conventional light localizing system, employing a single mirror and a light source. The superconducting magnet coil is close to the neutron producing target and the vacuum window separating the acceleration chamber from atmospheric pressure is situated approximately 56 cm from this target. Therefore, the light localizing system must be designed to incorporate lenses, mirrors, an optical fiber light pipe and adjustment motors, in order to make the system compact enough to fit in the available space and to allow easy access for adjustment and alignment. The design of the light localizing system is explained in detail.