Localization of debris on optical surface of vehicle

A method of assembling a system to localize debris on an optical surface of a vehicle, the method comprising:

• arranging a first array arranged along a first side of a perimeter of the optical surface, the first array including one or more light sources configured to emit light into a thickness of the optical surface, wherein the optical surface is defined by the perimeter, a first surface, a second surface opposite the first surface, and a thickness between the first surface and the second surface;
• arranging a second array along a second side of the perimeter, opposite the first side, of the optical surface, the second array including one or more light detectors configured to detect light scatter in the thickness of the optical surface and provide a corresponding output;
• arranging a third array along a third side of the perimeter, the third array including one or more light sources configured to emit light into the thickness of the optical surface;
• arranging a fourth array along a fourth side of the perimeter, opposite the third side, of the optical surface, the fourth array including one or more light detectors configured to detect light scatter in the thickness of the optical surface and provide a corresponding output;
• and
• configuring a controller to identify a presence of the debris and determine a position of the debris on the first surface of the optical surface based on the output from the one or more light detectors of the second array and the fourth array and to remediate the debris.