Non-contact film thickness gauging sensor

A sensor for the non-contacting thickness gauging of a film, comprising

• a sensor head which includes a bottom plate, and at least one non-contacting sensor element mounted on the bottom plate and which is capable of gauging the thickness of the film from the physical properties of the film when the film is located adjacent and spaced below the bottom plate, and a plurality of gas outlets extending through the bottom plate and directed toward the film, with the outlets arranged to encircle the sensor element,
• a mount mounting the sensor head for movement toward and away from the film,
• means for adjusting the position of the sensor head in the mount and comprising a gas supply connected to the gas outlets so that a gas flow is directed toward the film, and wherein a fine adjustment of the spacing between the bottom plate of the sensor head and the film occurs automatically by means of the gas flow, and wherein the gas flow generates a vacuum about the sensor element which acts to lift the film without contacting the bottom plate so that during the measuring procedure a predeterminable and essentially constant relative position is maintained between the bottom plate and the film in spite of any random movement of the film toward and away from the bottom plate, and
• a separate adjustment device for the coarse adjustment of the position of the sensor head in the mount, said separate adjustment device including a distance measuring sensor mounted on said sensor head and a drive for moving the sensor head in the mount in response to a signal from the distance measuring sensor.