An $aring$ngstr$ouml$m ruler

Abstract

As a first step in the establishment of an absolute scale of length in the region of 10−10 m an x-ray interferometer has been used to measure distances. In preliminary experiments several hundred high-contrast x-ray moiré fringes have been recorded, enabling distances from 0 to 0·1 μm to be measured with a precision of ±0·02 Å. Two novel features, x-ray interferometers working in the low absorption Laue-case (transmission geometry) and the extensive application of spring-strip elastic design, combine to give high intensity with almost perfect stability and backlash-free operation.