Contact free measurement appts. for detecting relative movement between parts

摘要

The measurement appts. measures the relative displacement between two parts (12) displaceable relative to each other. A measuring body (17) on one of the parts extends in its displacement direction and has a measurement division (24). A scanning head (18) is held on the other part to scan the measurement division, which is directly attached to a non-hygroscopic base material pref. ceramic. The measuring body may have a ceramic carrier (20) for the measurement division fixedly connected to the moving part (12). The ceramic carrier preferably has an expansion coefficient corresponding to that of the part to which the carrier is fixed. Alternatively, the measuring body may itself be formed from a moving part made of ceramic, which directly carries the measurement division, which is preferably formed of an electrically conductive layer (19) e.g. made of a chrome-nickel alloy. This layer preferably has a thickness of about 40 nm.