Patent attributes
A method of checking a deteriorated layer formed in the inside of a workpiece along a dividing line by applying a laser beam capable of passing through the workpiece to the workpiece along the dividing line formed on the workpiece, the method comprising a focusing step of positioning a microscope of infrared image pick-up means to the dividing line formed on the workpiece, and setting the focusing point of the microscope to a position where the deteriorated layer in the inside of the workpiece has been formed; and an image pick-up step of picking up an image of the inside of 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, wherein the deteriorated layer formed in the inside of the workpiece is checked based on the image picked up in the image pick-up step.
