Particles such as volcanic ash and supercooled water droplets can detrimentally affect aircraft performance. These particles typically have mean volumetric diameters (MVDs) of about fifty microns.
The supercooled water droplets form ice when contacting, e.g. an airfoil, of an aircraft. Icing of airfoils has caused aircraft catastrophes. Many modern aircraft are designed to include ice protected surfaces and fly in conditions of icing arising from supercooled water droplets of fifty microns or less.
There exist supercooled large water droplets having MVDs up to five thousand microns. Aircraft are not typically designed to fly in conditions of icing arising from supercooled large water droplets because such larger droplets (a) adhere to more of the aircraft surface than smaller droplets and (b) are more likely to move behind ice protected surfaces.
Because aircraft are not protected from supercooled large water droplets, it is important for an aircraft to detect their presence so that the aircraft and/or its pilot can take action to avoid resulting icing. Modern particle sensors using optical transceiver systems are not typically designed to detect the presence of particles having MVDs with a dynamic range of one thousand while maintaining adequate detection sensitivity over the particle size range. Typical high dynamic range particle detection systems unsatisfactorily sacrifice detection sensitivity, e.g. for relatively small sized particles, to increase particle size detection dynamic range. For example, this can result in an undesirable tradeoff—facilitating detection of large particles while diminishing the detection accuracy of small particles, such as volcanic ash—which could lead to aircraft engine damage or even failure. Therefore, there is a need for a particle detector that has both high dynamic range of particle detection size, while maintaining adequate detection sensitivity over the particle size range.