The light efficiency is a key point to acquire high resolution retinal images.Since the liquid crystal on silicon spatial light modulator (LCOS) can only modulate linearly polarized light,only half of the light reflected from the human eye is used in the traditional systems.The light efficiency for closed-loop systems is only 25% and for open-loop ones is 50%.An excess LCOS is applied in the dual-channel adaptive optics system proposed in this summary.The modulation directions of these two LCOSs are vertical to each other.Since any light can be divided into two linearly polarized lights (P-polarization light and S-polarization light),whose polarization directions are vertical to each other,these two LCOSs can modulate all of the light reflected from the human eyes.