Method for measuring fine particulates and fine particulate sensor for determining the particle size of fine particulates

A method for measuring fine particulates in the vicinity of a motor vehicle with an optical receiving device,

• wherein
• at least one LED arranged inside the motor vehicle lights up an outside air region through a windscreen of the motor vehicle,
• the optical receiving device is designed to capture the area under examination in a spatially localised manner and takes an intensity measurement in an area that is lit by the LED,
• the intensities measured are analysed for diffraction patterns that depend on the size of the fine particulates,
• the radiation emitted by the at least one LED is reflected at least in part by the windscreen, and
• the light reflected by the windscreen is received and analysed for wetting of the windscreen by water droplets.