Direction finding system

摘要

The present invention provides a direction finding system capable of positioning directions at two points, and particularly, for shifting a ground central base line and a reference point for tunneling work or the like to an underground tunnel shaft or the like, to position a digging thrust direction. A polarized light radiating device irradiates a body for the direction finding system with a polarized light beam or ray bundle and a direction difference detecting device provided within the body receives therein the polarized light beam emitted from the polarized light radiating device and detects the difference between the direction of the polarized light beam and a predetermined direction. A rotatory polarizing plate of the direction difference detecting device allows the polarized light beam to pass therethrough and a condenser lens gathers the polarized light beam transmitted through the rotatory polarizing plate. A light-receiving portion receives therein the polarized light beam gathered by the condenser lens and an encoder device detects a predetermined position and rotation of the rotatory polarizing plate.