| 摘要 |
PURPOSE:To measure the thickness of a film inexpensively and easily, by plotting measured values of angles of projection of a projection light, at which a peak value of the interference reflected light from an object to be measured should be obtained on plural multidegree curve graphs where known film thicknesses are X coordinates and said angles of projection of the projection light are Y coordinates. CONSTITUTION:Parallel beams of the light of a laser are radiated onto the surface of a magnetic disc 1 in parallel at an optional angle theta, a peak value of the interference light offers when the reflection on the surface of a substrate 2 and the reflection on the surface of a coating layer 3 are synthesized. In this case, plural thetan (n is the order of interference) appear in 0.5-1.5mum thickness of the coating film of the practical magnetic disc. Then, when the angle theta of irradiation, at which a peak value of the interference light offers, obtained by experiments is plotted on Y coordinates in the coordinate system with magnetic coating film thickness (d) as X coordinates, plural curves of orders of interference are obtained. Plural angles of interference irradiation of a disc to be measured are plotted on curves of orders of interference to read the thickness of the coating film. |
