An inspection system for the surface-profile properties of an organic photoconductor (OPC) drum substrate is studied. Defective substrates have approximately 1-mm-period waves in their surface profiles along the axial direction. The slope distribution of the surface profile is measured with an optical inspection system, which detects the angular deflection of a laser beam scanned over the surface at a high speed of 15 mm/ms. To discriminate between good and defective substrates, a threshold decision is made on components of the experimentally measured power spectrum of the slope distribution around 1-mm spatial period. The inspection system provides the same results as visual inspection with an accuracy better than 6. The setup dose not require any vibration isolators, because of its short inspection time of 2 ms.
The rough surface of a aluminum cylindrical drum cut by turning tool is measured with a fast scanning method by detecting angular deflection of a laser beam. Reflection pattern from the surface extended into a large region, and contained two kinds of components of narrow and wide patterns. To detect rough surface's slope, the barycentric position of the wide pattern was measured with a PSD, and a beam diameter of 5mm on the surface was adopted. After a proportionality coefficient to convert from PSD output to the surface's slope was determined, an one-dimensional surface profile measurement of the rough surface was performed without a vibration isolator. Measurement error was estimated to be 0.27μm.