| 摘要 |
PURPOSE:To measure the shape at a high accuracy by employing a semiconductor position detector having a 2-D light receiving surface as a photoelectric converter for detecting the (0)th diffracted light and the (n)th diffracted light to correct the deviation in the surface to be measured not affected by distortion or the like thereof. CONSTITUTION:An object 11 to be inspected is a disc-shaped one like an optical video disc. Light outputted from a light source 12 comprising a laser unit is reflected with a mirror 13 and incident on the object 11 being inspected at the angle of theta0 with respect to the normal thereof. After the entry into the object 11 being inspected, reflected and diffracted light is detected with two 2-D type semiconductor position detectors 14 and 15 and a photodiode 16 and the outputs separately undergo a signal processing. The pitch P, width (a) and depth (h) are determined with a signal processing calculator 17 of such a type and shown on a display section 18. To measure the object 11 being inspected entirely, under the control of the signal processing calculator 17, a motor 19 is driven to rotate the object being inspected while it 11 is moved parallelly with a motor 20. |
