Digital calipers📏what would we do without them? They were a true step-change improvement over mechanically driven calipers: orders-of-magnitude more accuracy, fast and reliable "zeroing", and vastly improved durability.
And they were invented by one guy: Ingvar Andermo. A Swedish scientist, he worked with the CE Johansson company (which specialized in precision measuring tools) to develop a new caliper system based upon magnetorestrictive principles.
But Andermo's expertise was in capacitive technology and he applied this knowledge to produce a simpler and far more elegant solution. Beneath the plastic strip that runs down the length of the calipers is an etched copper pattern. A similar circuit in the moving component slides across this pattern and can detect a predictable change in capacitance as it moves.
The first Johansson digital calipers ("Jocals") were demonstrated at an expo right here in Chicago, Illinois in 1980. Johansson licensed the technology to the Japanese firm Mitutoyo who went on to become the company most associated with this technology.