Abstract: The invention provides a device for determining the direction and speed of an air flow, comprising a chip which is provided with two mutually perpendicularly positioned pairs of measuring circuits placed at a distance opposite each other, optionally four heating elements in positions coinciding with the measuring circuits and a control circuit, which chip is fixed onto a substrate, characterized in that the mounting between chip and substrate is substantially homogeneous and preferably effected by gluing. The chip is for instance accommodated in a housing of conducting material. The device can contain in addition to the measuring chip a reference chip without heating elements which is embodied in substantially identical manner and which is shielded from the measuring chip by an insulator.

Abstract: A method of manufacturing multilayer mirrors for use in conjunction with X-rays. Customary multilayer mirrors are composed of discrete, thin layers which generally consist of alternating absorption and spacer layers. In order to counteract surface roughness of the thin layers, it is known to smoothen the layers by ion etching after deposition. A drawback thereof consists in that the material of one layer penetrates into the other layer, so that the location of the interface and the thickness of the layers of the multilayer mirror are no longer suitably defined. In accordance with the invention, a multilayer mirror is manufactured by stimulating the penetration of one of the materials into the layer with the other material, after which the original layer thickness of the first material is removed by etching.