Patent ID: 7244938

Claim:
A method of checking a laser processed deteriorated layer formed in a workpiece along a dividing line formed on the workpiece by applying a laser beam capable of passing through the workpiece along the dividing line, the method comprising: a step of preparing an infrared image pick-up means having a microscope with an adjustable focusing point, the microscope being movable in a moving direction relative to the workpiece and having a standard line in a field of vision thereof, the standard line being parallel to the moving direction; a focusing step of positioning the microscope opposite the dividing line on the workpiece, and setting the focusing point of the microscope to a position where the deteriorated layer in the workpiece has been formed; an image pick-up step of picking up an image within the workpiece by moving the infrared image pick-up means and the workpiece along the dividing line relative to each other to scan the workpiece; and checking a shift of the picked up image of the deteriorated layer from the standard line to determine whether the deteriorated layer is formed on a predetermined line corresponding to the dividing line in the workpiece.