Patent ID: 7986408

Claim:
An airborne water droplet and ice crystal sensor, comprising: an illumination portion comprising: a first optical beam emitter configured to output a light beam; a first linear polarizer configured to receive the light beam and output a linearly polarized illuminating beam; a first circular polarization element configured to receive the linearly polarized illuminating beam and output a circularly polarized illuminating beam; and a detection portion comprising: a window configured to permit circularly polarized backscattered light to pass therethrough; a second circular polarization element configured to receive the circularly polarized backscattered light that has passed through the window and output linearly polarized backscattered light; a first polarizing beam splitter configured to split the linearly polarized backscattered light into a first component linearly polarized backscattered light and a second component linearly polarized backscattered light; a first light detector configured to detect the first component linearly polarized backscattered light and output a first signal in response thereto; a second light detector configured to detect the second component linearly polarized backscattered light and output a second signal in response thereto; a a second linear polarizer interposed between the first polarizing beam splitter and the first light detector, the second linear polarizer configured to further linearly polarize the first component linearly polarized backscattered light, prior to detection by the first detector; and a processor configured to receive the first and second signals output by respective first and second light detectors, and calculate at least one parameter reflective of an ice condition, based on said first and second signals.