| 摘要 |
PURPOSE:To enable a highly accurate measurement of the surface roughness of an object to be measured handily by a method wherein an interference fringe due to an interference of both reflected lights from the reference surface and the surface of an object to be measured and the movement thereof is detected with a photo sensor. CONSTITUTION:A laser beam 10 from a laser oscillator 1 passes through a reference plane 4 via a beam splitter 2 and a lens 3 forming a focus on the surface of an object 6 to be measured and reflected lights enters a sensor 8 as plane wave. On the other hand, light reflected on the surface of the reference plane 4 also enters the sensor 8 but forms a spherical wave as the plane 4 is outside of the focusing position of a condensor lens 3. According to the distance between the plane 4 and the object 6 being measured, a bright and dark ring is generated in the interference fringe of two reflected lights. As a moving base 5 is moved, with fine irregularities on the surface of the object 6 being measured, a fine change occurs in the distance from the plane 4, causing the interference ring to move. This enables a highly accurate measurement of the surface roughness of the object being measured while correcting the interval of the interference fringe thereby improving the accuracy. |
