what know about blue glass IR filter?
Every digital camera has an IR cut filter to adapt the spectral sensivity of the sensor to that of the human eye. The trend to backside illuminated CMOS chips enable higher “light gathering”, especially under higher angles of incidence (field of view). Due to the virtually angle-independent transmittance characteristics of absorptive filter glasses (e.g. IR blocking so-called “blue glass”), blue glass is more and more used. Pure interference filters have a high angle dependency and in addition reflect the IR light which can cause ghost images. A typical design of a smart phone camera will be used to design and analyze the quality of a blue glass absorption filter. Blue glass as plano-plano filter plate in front of a CMOS chip will be examined. Furthermore, a lens made out of blue glass (substituting the plano-plano filter) will be designed and analyzed. It turns out that the blue glass lens can be used as a crown glass in an achromatic lens. The required transmittance (filter) curve w...