US Patent 9784575 Optical device with a measurement scale

An optical device with at least one measurement scale for the determination of the distance to an object with an at least approximately known size observed by the measurement scale. In order to make possible a quick, object size-independent readability of measurement values and a simpler calculation of the distance to an object from the read-off measurement values, the measurement scale includes a reference marking and at least one additional measurement marking with a numerical value that is correlated with it and that is inversely proportional to the distance of the reference marking from the pertinent measurement marking. The distance to the object observed by the measurement scale is produced by a multiplication of the size of the object with a measurement value read off from the measurement scale.