US Patent 7019908 Modulator circuitry

The invention relates to a modulator for modulating the magnitude of a beamlet in a multi-beamlet lithography system, said modulator comprising at least one means for influencing the direction of a beamlet, a light sensitive element for receiving light from a modulated light beam and converting said light into a signal, and discretizing means, coupling to said light sensitive element and to at least one of means for influencing, for converting said signal received from said light sensitive element into a discrete signal having discrete values selected from a set of predefined discrete values and providing said discrete signal to said means for influencing.