| Abstract |
The device contaj.ns ii measuring gap whj.ch .LS prov.id(~d for t.r,e passage of the test nlate:t.-ia.1 and on each of the two side walls of whj.ch i.s provided a measuring elec'trode forming part of a capacit.i.ve raeasuring element. An optical measuring element. having ~ light source aI-ranged on one side of the measuring gap and having a photoelectri.c element is provided in a,jdition to the capacitive measuring element and both measuring elements form part of. a common measuring head. . ~'he fluctuations in accuracy of previous measuring heads having only one measuring element are thereby reduced and there is the possibility of the automatic checking of the measuring head. In addition, measurands which could not be detennined with the previous measuring heads can be measured and monitored. |