Electrical Instrument Adjustment for a Surface Profile
Original Publication Date: 1978-May-01
Included in the Prior Art Database: 2005-Feb-21
A surface profile instrument is a commonly used instrument to measure deposition thickness. It measures the distance between an optical flat and a stylus drawn across the sample. The distance is measured by a change in inductance in a bridge circuit. For every sample, the optical flat must be made exactly parallel to the surface of the sample that is to be measured. This is normally performed by rocking the stylus back and forth while the height and slope of the arm that contacts the optical flat is ultimately adjusted. The circuitry in the figure provides an easy method of adjustment by subtracting a voltage proportional to the distance travelled from the output voltage to provide an "artificial horizontal".