1. A display system comprising: a display screen; a plurality of subsystems each including a light source to generate at least one beam, the at least one beam including an excitation beam that carries image information, a beam scanning module to receive the at least one beam and to direct the at least one beam onto a display region of the display screen, the beam scanning module configured to scan the at least one beam along a scanning direction across the display region, the display screen comprising at least one servo feedback mark in the display region, a servo feedback detector positioned to receive feedback light of one or more of the at least one beam scanning on the display region, to detect the servo feedback mark from the feedback light, and to produce a monitor signal indicative of a position of the at least one beam on the display region, and a control unit operable to adjust optical energies carried by the excitation beam using one or more scaling factors, wherein two adjacent subsystems of the plurality of subsystems are configured such that in operation an area scanned by one or more excitation beams of a first subsystem of the adjacent subsystems overlaps with an area scanned by one or more excitation beams of a second subsystem of the adjacent subsystems in an overlap region; and a control system coupled to the plurality of the subsystems and configured to determine a range of the overlap region between the adjacent subsystems based on the monitor signals from the servo feedback detectors of the adjacent subsystems, and determine the scaling factors for the excitation beams for the overlap region of the adjacent subsystems.