Optical sensor and apparatus comprising an optical sensor having a photodetector and a semiconductor guard ring are dimensioned so that a fill factor of each pixel is less than or equal to 50%

An optical sensor comprising a plurality of pixels arranged in an array with a pitch, wherein each pixel comprises:

• a photodetector and a semiconductor guard ring around the photodetector;
• wherein the photodetector and the semiconductor guard ring are dimensioned so that a fill factor of the pixel defined by a ratio of an area of the photodetector to an area defined by the pitch for the plurality of pixels is less than or equal to 50%.