sheet 17 with the exception of its gripping strap 17 39 are coated with a highly transparent adhesive gel 15 the gel is composed of the same material as gel 5 of the first exemplary embodiment the adherence between gel 15 and support sheet 17 is greater than between gel 15 and the front side of the sensor for a measurement adhesive lamina 16 is applied on the front of the sensor the side of adhesive lamina 16 not facing or remote from sensor front side is then installed on the measurement surface of the object to be measured of course it is also possible to first install the adhesive lamina 16 on the measuring point and thereafter to initiate the use of the sensor also in this case a good adhesive connection for the most part suppresses the formation of artifacts and provides an optimum optical coupling support sheet 17 has an optical density at least nearly identical to the optical density of gel 15 and can improve the electrical insulation of radiation transmitter 12 and radiation receiver 13 relative to the skin surface of the person being tested the exemplary embodiment shown in fig3 is intended for installation on the nose of a person one end of a four polar connection cable 24 is subdivided in its middle and is spread apart in a y shape the one pair of conductors is soldered onto radiation transmitter 22 while the other pair is soldered onto radiation receiver.