Test arrangement for the contactless ascertainment of flows in non-structured surfaces

摘要

For the identification of defects in a non-structured surface, the surface to be investigated scanned with a scanning light ray wherein the light scattered and defracted by a defect is collected on a light sensitive surface of an opto-electronic receiver. In order to also be able to detect defects in a submicrometer range, a diaphragm for reducing the scattered light components in the scanning light ray prior to reaching the surface being tested is provided in the path of the scanning ray and has at least two diaphragm edges which are successively arranged in the diaphragm so that they respectively block out or cover only the shadow region of the preceding diaphragm edge. The test installation is particularly useful in testing a mask which has not yet been structured.