Panasonic Announces Technology to Improve CMOS Sensor Sensitivity (page 2)
Manufacturable with common semiconductor processes
The second elemental technology (device technology) enables to make the micro color splitter by using commonly-used semiconductor processes. With the micro color splitter, light is dispersed because of the refractive index difference between a plate-like high-refractivity material (which is thinner than light wavelength) and a material around it. In other words, it is possible to control the phase of transmitted light by changing shape parameters, generate a diffraction phenomenon in minute areas and separate light by color.
The micro color splitter can be formed by using common semiconductor processes. By changing its shape, it is possible to separate light into specific colors and their complementary colors without reducing the amount of light as well as to separate light into colors ranging from blue to red like prism, Panasonic said.
Technology used after color separation
The layout technology and algorithm are necessary for the process that comes after color separation with the micro color splitter. The lights separated by the splitter come to the detector plane of the image sensor in a mixed state. Therefore, it is necessary to design a pixel layout so that it becomes possible to cope with lights in such a state.
By combining the layout and an arithmetic processing technology for mixed color signals and optimizing them, Panasonic enabled to reproduce high-sensitivity, high-resolution color images. For example, with a structure that separates light into primary colors and complementary colors, four colors, which are "white + red," "white - red," "white + blue" and "white - blue," can be obtained. And it is possible to convert them into normal color images without deteriorating resolution by arithmetic processing.
Some of the latest results were published on the online version of Nature Photonics Feb 3, 2013. Panasonic has received or filed applications for 21 patents in Japan and 16 patents in other countries for the micro color splitter.