A compound of RGB-splitter and condensers for compact image sensor

A compound of a color splitting blazed grating and a condenser microlens array is discussed for an improvement of the optical power utilization efficiency in a compact color image sensor. Each segment includes the compound lens and three PDs assigned to red, green, and blue colors. Its color-splitting performance was simulated by two-dimensional finite-difference time-domain (FDTD) method. By adjusting the size of PDs for red, green and blue, it is found that the spectral characteristics can be closer to the ideal NTSC imaging characteristics. Detection optical powers are expected to be double in comparison to an image sensor with color filters.