| 摘要 |
PURPOSE:To elevate the detection and separation capacity with an improved contrast in the dark view illumination, by controlling the focus of a lens receiving the scattered light of an illumination light due to surface defects of an object to be inspected so that the focus position thereof falls on the objects being inspected. CONSTITUTION:Light emitted from a light source 15 is made to irradiate an object 11 to be inspected skewly through a doughnut-shaped mirror 1 and a ring-shaped condenser 21 to make a dark view illumination light. The scattered light due to surface defect of the object 11 being inspected forms an image on a 1-D arrayed multi-element photo detector 23 through an objective lens 20 and a lens 22. A lens lift mechanism such as voice coil 30 mounted on the lens 20 is regulated from the detection output of a 2-element photo detector 29 using light of a focus controlling light source 24 to control the focus thereof. The width of scan with the rotation of the object 11 being inspected is determined corresponding to the number of elements and the pitch in the detector 23. For example, when the number of elements and the pitch are set at 32 and 60mum, the linear area of 32mum can be inspected simultaneously by the separation capacity of 1mum. |
