a method of determining a position of a laser beam in an electrophotographic machine includes providing a sensor device having a laser beam receiving surface with a first edge and a second edge . the second edge is nonparallel to the first edge . the laser beam is scanned across the receiving surface in a scan direction perpendicular to a process direction . the laser beam intersects each of the first edge and the second edge of the receiving surface during the scanning . a time period between when the laser beam intersects the first edge and when the laser beam intersects the second edge of the receiving surface is measured . a process position of the laser beam along the process direction is calculated based upon the measured time period .