To monitor light pulses from a light source, such as a laser, sense signals are provided to a photosensing component or array, causing photosensing during a series of one or more sense periods for the light pulse. Each light pulse can be provided through a transmission structure, such as a layered structure, that provides output light with an energy-dependent position on the photosensing component. A pulse's sensing results can be used to obtain a set of one or more differential quantities; for example, with a photosensing array, two cells of the array can be read out and compared. For a narrow band light pulse, a transmission structure can provide a spot on the photosensing component, and the light spot position can be sensed.