Thickness measurement of an opaque object
If the thickness of e.g an opaque object is to be determined, two measuring heads are required, one from each side. By referencing with a test standard of known thickness, the thickness of the object can be obtained from the data on the distances to the two surfaces. This principle is not affected by displacements or vibrations of the object. If it comes closer to one measuring head, it moves away from the other; the calculation of the thickness is not affected. This makes the system highly suitable for inline applications where, for example, a passing strip (as an object) cannot be guided or only guided to a limited extent, or for roll-to-roll applications with high web speeds. The CHRocodile 2 DPS sensor can measure at up to 10 kHz, which means that even large or fast-moving objects can be closely scanned.
Step height measurement
Another possible application is the instantaneous determination of a step height without the time-consuming acquisition of a complete profile of the step. If both measuring heads are oriented in the same direction, the height difference between two locations on a surface can be determined. This is interesting, for example, for continuous inline control of the thickness of a coating or to determine the thickness of an object that cannot be reached from the bottom for geometrical reasons. For example, the thickness of a wafer on a chuck table can be determined by measuring the step height between the wafer surface and the chuck table. The internal calculation and referencing can be easily adjusted to this situation so that the CHRocodile 2 DPS directly outputs the calculated step height without further post-processing.
Thickness information can also be included in this application so that composite objects with transparent layers can also be measured here.