Abstract: An illuminated level has a housing containing a solid body pivotally mounted in the housing and forming a pendulum which can pivot to a first position in which the surface is accurately level. A light path is provided through the solid body having an exit opening at the pivot point and an entry opening the opposite end. A source of laser light on the housing is arranged to transmit light through an orifice on the housing so that the light through the orifice enters the entry opening to pass along the path when the solid body is in the first position and is prevented from entering the entry opening when the solid body is out of the level position. A light receiver in the housing at the outlet is responsive to the passage of light through the path for providing a sound indicating when the solid body is in the first position.

Abstract: An illuminated level has a housing containing a solid body pivotally mounted in the housing and forming a pendulum which can pivot to a first position in which the surface is accurately level. A light path is provided through the solid body having an exit opening at the pivot point and an entry opening the opposite end. A source of laser light on the housing is arranged to transmit light through an orifice on the housing so that the light through the orifice enters the entry opening to pass along the path when the solid body is in the first position and is prevented from entering the entry opening when the solid body is out of the level position. A light receiver in the housing at the outlet is responsive to the passage of light through the path for providing a sound indicating when the solid body is in the first position.