METHOD OF SUPPRESSING FALSE POSITIVE SIGNALS DURING SELF MIXING INTERFERENCE PARTICLE DETECTION

• Main Authors: SPRUIT, Johannes, Hendrikus, Maria, OUWELTJES, Okke, VAN DER LEE, Alexander, Marc, JUTTE, Petrus, Theodorus
• Format: Patent
• Language: English; French; German
• Published: 15.04.2020
• Subjects: ANALOGOUS ARRANGEMENTS USING OTHER WAVES; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION ORRERADIATION OF RADIO WAVES; MEASURING; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS; MEASURING LENGTH, THICKNESS OR SIMILAR LINEARDIMENSIONS; PHYSICS; RADIO DIRECTION-FINDING; RADIO NAVIGATION; TESTING

The invention relates to a method of measuring a particle density of particles (10) with a size of less than 20 µm, preferably less than 10 µm in a fluid, the method comprising the steps of: emitting a laser beam (112) to a mirror (160), dynamically redirecting the laser beam (112) by means of the mirror (160) with a predetermined periodical movement, imaging the laser beam (112) to a detection volume, by means of an optical imaging device (171), allowing determination of a self mixing interference signal of an optical wave within a laser cavity of the laser if the self mixing interference signal is generated by laser light of the laser beam (112) reflected by at least one of the particles (10), suppressing of a false self mixing interference signal if the self mixing interference signal is caused by a disturbance in an optical path of the laser beam (112). The invention further relates to a laser sensor module (100), a particle detector (200) and a device (190) comprising such a laser sensor module (100). The invention finally relates to a corresponding computer program product.