An imaging sensor device is configured to illuminate a viewing field using an array of focused light spots spaced across the viewing field rather than uniformly illuminating the viewing field, thereby reducing the amount of illumination energy required to produce a given intensity of light reflected from the spots. In some embodiments, the imaging sensor device can project an array of focused light spots at two different intensities or brightness levels, such that high intensity and low intensity light spots are interlaced across the viewing field. This ensures that both relatively dark and relatively bright or reflective objects can be reliably detected within the viewing field. The intensities of the light spots can be modulated based on measured conditions of the viewing field, including but not limited to the measured ambient light or a determined dynamic range of reflectivity of objects within the viewing field.