A modular approach to a pattern illumination system for selective excitation of microparticles is used. A dual-channel pattern module having two single-channel pattern modules are oriented at a non-zero offset angle to each other. In this arrangement, a galvo-scanner based phase-shifting module is shared between the two channels. A set of tilt mirrors are used to direct the beams from the pattern modules onto the target plane. Additional layers of pattern modules can be added to accommodate any desirable number of additional channels. The additional layer(s) may be rotationally off-set from the other layer(s) by an angular amount to simplify the layout of optical components. A remote light source module may be connected to the pattern modules through optical fiber.