Diffusive tip assembly

Optically transmissive fiber tip assemblies having radiation-scattering particles (24) incorporated therein are disclosed for use in phototherapy. In one embodiment, diffusers with reflective end caps are disclosed. As radiation propagates through the fiber tip, a portion of the radiation is scattered in a cylindrical (or partially cylindrical) pattern along the length of the fiber tip. Radiation which is not scattered during this initial pass through the tip can be reflected by at least one surface (28) of the assembly and returned through the tip. During this second pass, the remaining radiation (or at least a major portion of this returning radiation) again encounters the scatterers which provide further radial diffusion of the radiation. The scattering medium (22) and the reflective end cap can interact to provide a substantially uniform (or other predefined) axial distribution of laser radiation over the length of the tip apparatus. In another embodiment, diffusive loop assemblies are disclosed for diffusing radiation from an optical fiber. Disposed sheaths are also disclosed, as are integral stopper devices which limit the penetration of the apparatus. The devices of the invention are useful for various medical purposes as well as the sterilization of medical instruments.