Focusing of Radiation by a Gravitational Field.

A discussion is given of the focusing effect of gravitating bodies due to the curvature in the trajectory of light rays passing near them. The intensity distribution is derived for radiation passing close to a spherically symmetric body in the geometric- and wave-optics approximations. The possibilities of observing the effect are examined. The conditions most favorable for detection would be the observation of a distant source through the Galactic Bulge region.