A method may comprise: supplying light energy from a light emitting device principally along a first axis; sensing the light energy with a light sensing device oriented along a second axis, wherein the second axis is oriented substantially orthogonally to the first axis; and adjusting the light energy in response to the sensed light energy. In this way, an amount of retro-reflected light incident at the light sensing device may be reduced, measurement error of the light sensing device may be reduced, and control precision and reliability of the lighting system for curing a work piece can be increased.