Surveying instrument indicating plane in space - has light source directed to rotating head with two prisms

摘要

The instrument provides increased accuracy through a wider area in marking out a plane in space i.e. to simplify level finding and sighting in surveying work. A light source, pref. a laser, emits light in the direction of rotating directing organ, which is driven by a motor. The reference plane to be marked out may be horizontal to or at a tilted angle to the ionstrument. The rotating instrument head has two pentaprisms, which are so arranged in respect of a beam divider between them and the laser, divergent lenses and convergent lenses, that two bundles of light are emitted. These and the speed of rotation are pref. such that the human eye if in the plane sees the emitted light as continuous, whereas if outside the plane the light appears as flashes.