A method and system for using spatially modulated excitation/emission and relative movement between a particle (cell, molecule, aerosol, . . . ) and an excitation/emission pattern are provided. In at least one form, an interference pattern of the excitation light with submicron periodicity perpendicular to the particle flow is used. As the particle moves along the pattern, emission is modulated according to the speed of the particle and the periodicity of the stripe pattern. A single detector, which records the emission over a couple of stripes, can be used. The signal is recorded with a fast detector read-out in order to capture the “blinking” of the particles while they are moving through the excitation pattern. This concept enables light detection with high signal-to-noise ratio and high spatial resolution without the need of expensive and bulky optics.