Image sensor withstands extreme weather, heat

Matsushita Electric Industrial Co. Ltd has developed a robust and lightfast image sensor that is extremely resistant to weather, heat and UV deterioration and can be used under harsh sunlight for over 20 years.

Unlike traditional image sensors with polymer on-chip microlenses and dyed color filters, the robust MOS image sensor has digital microlenses and photonic color filters, both made of inorganic materials that are inherently fade-resistant and quite robust, said the company.

Conventional MOS image sensors require polymer on-chip microlenses and dyed RGB color filters, which are fragile and extremely susceptible to sunlight exposure and a change in temperature. As a result, color images captured by a camera used under direct sunlight, including the UV portion and higher temperature conditions will fade faster. The semiconductor process technology can realize the pattering of an array of digital microlenses made of an inorganic material in subwavelength dimensions.

A digital microlens can be formed by digitally patterning the inorganic material in concentric rings, which works out as a conventional on-chip microlens to gather more light onto the photo diode area. The light path of each digital microlens can then readily be designed according to its relative position on the image area. This enables a uniform sensitivity across the image area in any camera module used.

Moreover, photonic color filters made of inorganic materials have been implemented for the first time by the photonic crystal technology, which allows the photonic color filters to select any colors from the UV to the IR spectral regions. The photonic color filters can also provide different camera modules with "lightfastness" that is essential for applications such as security cameras and automotive cameras.