A range finding device includes a light-emitting unit including light-emitting regions; an optical element to guide light emitted from the light-emitting unit; a light-receiving unit including light receiving regions to receive light reflected from an object; and circuitry to control light emission amount of the light-emitting regions; measure an amount of light received at the light receiving regions; measure a distance to the object by measuring a time difference between a start time when the light is emitted from the light-emitting unit and a time when the light reflected from the object is received by the light receiving regions; cause the light-emitting regions to emit the same light amount as a preliminary light emission stage; control the light emission amount of the light-emitting regions for a main light emission stage based on the amount of light measured at the preliminary light emission stage; and measure the distance to the object.

An electronic device such as an earbud may have control circuitry mounted in a housing. The housing may have portions such as an ear portion with a speaker port through which a speaker plays audio and a stalk portion that extends from the ear portion. Proximity sensors may be formed in the electronic device. For example, one or more proximity sensors may be formed on the ear portion to detect when a user has inserted an earbud into the ear of the user and/or one or more proximity sensors may be formed on a stalk portion to detect when a user is holding an earbud by the stalk or when a user is providing finger touch input such as taps, swipes, and/or other gestures on the stalk portion. The proximity sensors may be optical proximity sensors such as coherent self-mixing proximity sensors.

The invention describes a laser sensor module (100) for particle size detection. The laser sensor module (100) comprises at least one first laser (110), at least one first detector (120), at least one electrical driver (130) and at least one evaluator (140). The first laser (110) is adapted to emit first laser light in reaction to signals provided by the at least one driver (130). The at least one first detector (120) is adapted to determine a first self-mixing interference signal (30) of an optical wave within a first laser cavity of the first laser (110). The first self-mixing interference signal (30) is caused by first reflected laser light reentering the first laser cavity, the first reflected laser light being reflected by a particle receiving at least a part of the first laser light. The evaluator (140) is adapted to determine a size of the particle by determining a first relative distance between the particle and the first laser (110) by means of the first self-mixing interference signal (30) and by determining a first amplitude information by means of the first self-mixing interference signal (30). The invention is further related to a corresponding method of determining a particle size.

An optical proximity sensor includes a first vertical cavity surface-emitting laser configured for self-mixing interferometry to determine distance to and/or velocity of an object. The optical proximity sensor also includes a second vertical cavity surface-emitting laser configured for self-mixing interferometry to determine whether any variation in a fixed distance has occurred. The optical proximity sensor leverages output from the second vertical cavity surface-emitting laser to calibrate output from the second vertical cavity surface-emitting laser to eliminate and/or mitigate environmental effects, such as temperature changes.

A method of measuring a particle density of particles includes emitting, by a laser, a laser beam directed to a mirror, redirecting the laser beam by the mirror with a predetermined periodic movement, and focusing the laser beam to a detection volume by an optical imaging device. The method further includes determining a self mixing interference signal of an optical wave within a laser cavity if the self mixing interference signal is generated by laser light of the laser beam reflected by at least one of the particles and suppressing a false self mixing interference signal for particle detection if the self mixing interference signal is caused by a disturbance in an optical path of the laser beam. The false self mixing signal caused by the disturbance in the optical path of the laser beam is suppressed in a defined range of angles of the mirror during the periodic movement.

The present invention relates to a coherent frequency modulated continuous wave (FMCW) lidar system, and more particularly, to a coherent FMCW lidar system including: a lidar sensor unit configured to generate an amplified laser by interfering a first FMCW laser, which is reference light, and a second FMCW laser, which is transmitted over sea and reflected, in a coherent scheme, and detect a marine object information signal from the amplified laser; a control unit (200) configured to process the marine object information signal received from the lidar sensor unit (100) into an image; and a housing unit (10) configured to house the lidar sensor unit (100) and the control unit (200).

A particle sensor that includes a first laser Doppler sensor and at least a second laser Doppler sensor, as well as a control unit that is configured to carry out self-interference measurements with the first laser Doppler sensor and simultaneously with at least the second laser Doppler sensor.

A laser sensor module for detecting a particle density of particles, which includes: a laser; a detector; and a mirror. The laser is arranged to emit a laser beam to the mirror. A movement of the mirror is arranged to redirect the laser beam. The laser beam is displaced with respect to a rotation axis of the mirror such that a focus region of the laser beam is moving with a velocity having components normal and parallel to the optical axis of the redirected laser beam such that an angle between the parallel and the normal velocity component is at least a threshold angle of 2. The detector is arranged to determine a self mixing interference signal of an optical wave within a laser cavity of the laser, the self mixing interference signal being generated by laser light of the laser beam reflected by at least one of the particles.

A self-mixing interferometry sensor module, comprising a light emitter (LE), a detector unit (DU) and an optical element (OE), wherein the light emitter (LE) is operable to emit coherent electromagnetic radiation towards an external object (ET) to be placed outside the sensor module and undergo self-mixing interference, SMI, caused by reflections of the emitted electromagnetic radiation from the external object back inside the sensor module. The detector unit (DU) is operable to generate output signals indicative of an optical power output of the light emitter (LE) due to the SMI. The optical element (OE) is aligned with respect to the light emitter (LE) such that a first fraction of electromagnetic radiation is directed towards the external target (ET) or the light emitter (LE) and a second fraction of electromagnetic radiation is directed towards the detector unit (DU). An optical power ratio determined by the first and second fractions meets a pre-determined value.

A range finding device includes a light-emitting unit including light-emitting regions; an optical element to guide light emitted from the light-emitting unit; a light-receiving unit including light receiving regions to receive light reflected from an object; and circuitry to control light emission amount of the light-emitting regions; measure an amount of light received at the light receiving regions; measure a distance to the object by measuring a time difference between a start time when the light is emitted from the light-emitting unit and a time when the light reflected from the object is received by the light receiving regions; cause the light-emitting regions to emit the same light amount as a preliminary light emission stage; control the light emission amount of the light-emitting regions for a main light emission stage based on the amount of light measured at the preliminary light emission stage; and measure the distance to the object.