(under subclass 228) Subject matter wherein the material tested has two different surfaces, and the distance between the surfaces is measured by placing the two surfaces in the magnetic field and the apparatus to sense and indicate the sensing of the field is responsive to the field as modified by the material between the two surfaces to thus sense and indicate the distance between the surfaces.
(1) Note. Class 324 measures thickness by sensing a change in magnetic property of magnetic test. For measuring thickness by having contacts touching the tested material, see the Search Note below.
SEE OR SEARCH CLASS
33, Geometrical Instruments, measures thickness by having contacts touching the tested material; see
783+, for distance measuring devices, particularly subclass 835 for coating thickness measurement, and subclasses 174+ for gauges.
73, Measuring and Testing,
37.5, for the measurement of a dimension of a material by fluid means.
250, Radiant Energy, appropriate subclasses for the measurement of a dimension of a material by invisible radiation. 356, Optics: Measuring and Testing,
380, for determining the thickness of light permeable material.
374, Thermal Measuring and Testing,
7, for a thickness determination by a thermal test.
