Patent ID: 7119900

Claim:
A pollen sensor comprising: an illumination portion for generating a light beam having an incident optical axis for illuminating particles floating in air in a detection zone of the pollen sensor, with the light beam polarized in a given direction perpendicular to the incident optical axis; a first receiver aligned at a first angle with respect to said incident optical axis for selectively measuring the intensity (Ip) of light beams from the detection zone polarized parallel to the light beam polarized in said given direction from said illumination portion with the light beam selected from a group of light beams scattered by said floating particles; a second receiver aligned at a second anale spaced radially apart from the alignment axis of said first receiver to form a complementary angle of substantially equal dimension with respect to said incident optical axis for measuring the intensity (Is) of light beams from the detection zone polarized perpendicular to the light beam polarized in said given direction from the illumination portion with the light beam selected from the group of light beams scattered by the floating particles; and means for discriminating pollen particles from other floating particles including means for computing the degree of polarization of such particles as an arithmetic value from the intensity (Ip) of the polarized light beam detected by the first receiver and the intensity (Is) of the polarized light beam detected by the second receiver.