Device and method for optical inspection

Device for optical inspection comprising a scanner which is arranged for detection and measurement of defects in or on a material which is inspected, with said inspection taking place in successive sweeps essentially in the transverse direction of the material, with each respective sweep corresponding to a plurality of pixels in said scanner, said device comprising a central computer unit with a memory unit, with the computer unit or the memory unit being arranged for storage of a rolling buffer comprising at least one sweep which precedes the sweep which is stored, by means of at least one pixel indicating triggering corresponding to a detected defect in the material.

Method for determining the size of a defect during optical inspection using a scanner which is arranged for detecting and measuring defects in or on a material which is being inspected, said inspection being carried out with successive sweeps essentially in the transverse direction of the material, with the respective sweep corresponding to a plurality of pixels of said scanner, wherein said method comprises:

• measuring how much time it takes for the material to be transported a predetermined distance,
• calculating a distance constant which corresponds to time between each sweep along the material, and
• computing the size in the y-direction of the defect starting from said distance constant.