Retroreflective device for use with an EDM total station

摘要

A retroreflector 1 for use as an EDM Total Station target comprises a plurality of retroreflective elements 4 disposed in an arc of constant radius. The retroreflector may have releasable attachment means (7 and 8, Fig 2) such as a magnet for attaching it to a structure. The retroreflector may also have a semi-disc shaped body 2 with the retroreflective elements, which may be in the form of a retroreflective sheet material, mounted to the curved face 3 of the body. A sighting element (16, Fig 3) encompassed in a transparent layer (15, Fig 3) on the body may project axially from the body at the centre of the arc's curvature. A method of surveying ferromagnetic posts (12, Fig 5) either side of a permanent way (11, Fig 5) using the magnet mounted retroreflector is also disclosed.