The method includes emitting light rays from each light source in a set of at least four light sources in a serial manner, and reflecting at least a portion of the light rays emitted from each of {HEAD ~ the light sources} from {TAIL ~ an encoded scale} 
The method includes emitting light rays from each light source in a set of at least four light sources in a serial manner , and reflecting at least a portion of the light rays emitted from each of { HEAD ~ the light sources } from { TAIL ~ an encoded scale }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL