1. A computer-based method for inspecting a wafer, comprising: storing, in a memory element for at least one computer, computer readable instructions; detecting, using a detector, a first light beam rotating in a first spiral about a first central axis; and, executing, using a processor for the at least one computer, the computer readable instructions to: generate, using the detected first light beam, an image including at least one shape; determine an orientation of the at least one shape or a size of the at least one shape; and, calculate a depth of a defect within the wafer according to the orientation or the size, wherein: the at least one shape includes a plurality of shapes; and, determining the orientation of the at least one shape includes determining respective positions of the plurality of shapes with respect to rotation about a point in the image.