An apparatus for minimizing position measurement errors caused in the case of a contactless determination of

摘要

A device for detecting or determining the mass or mass fractions of a test piece or of the grammage or surfaces masses proportions of layered material of a material to be measured (4) with the aid of the back scattering method, comprising at least one radiation source (1) for generating a on the product being measured (4) incident initial radiation (3), at least one detector device (2) for the purpose of accommodating at least a part of a scattered radiation (6) of the product being measured (4) scattered initial radiation (3) and at least a scattered radiation adaptation a direction (7), which is designed, at least a part of the scattered radiation (6) into a measuring radiation (6a) to be modified, wherein the measurement radiation (6a) of the detector device (2) can be accommodated, characterized in that the scattered radiation adaptation a direction (7) a light dimming rear-view element (7a) is that the scattered radiation (6) in accordance with the position of their occurrence location (6) and thus trims the beam cross section of the measuring radiation (6a) in a suitable manner in order to signal the action of the 1 / r²-Distance law in the case of approach of the formation of location of the scattered radiation (6) to the a position location of the detector device (2) to counteract.