Digital photography gives people many benefits, but still has some things lacking. One of them is inability to take pictures in insufficient light exposure conditions. In such situations the voltage of a photoelectric signal produced by a cell of a matrix is low in comparison with thermal noise.
To increase a signal-noise ratio I suggest placing a small mirror or 2-D matrix of microscopic mirrors behind of the basic matrix sensitive to light. It will give the following effect: the ray of light will pass through a matrix, perform useful work, then will be reflected from a mirror and on a back way will pass through a matrix again, having created a useful signal the second time. Thus, the signal produced by a cell will be increased by 2 times on a voltage and 4 times on power.
This way of improvement seen in darkness (night vision) is used by nature in a structure of an eye of predatory animals, for example, panthers. Their back surface of a retina of an eye apple has a mirror covering. Therefore their eyes "are shone" in darkness. Actually, they concentrate and reflect back light which has got in an eye through a pupil.
In addition to coating of objective optics I suggest to apply coating of matrix surface.
As we know, the best objectives have coated optics. It represents a thin film on lens surface.
For best color separation I offer that thickness of coating film will depend on length of a wave of light for each cells group. Red light has long length of a wave, green – middle, blue – short, therefore for the cells sensitive to red light thickness of a film is bigger, for green - middle, for blue – smallest. It is necessary to waves of light, direct and backward, reflected inside of a covering substance and was summarized in one phase on a surface of a matrix.