An optical proximity sensor includes an optical path extender that extends an optical path length of the optical proximity sensor without a corresponding extension of a geometric path length of the optical proximity sensor. The optical path extender may be a high-refractive index material positioned along the optical path through the optical proximity sensor. The optical path extender may include one or more redirection features configured to change a direction of the light traveling within the optical proximity sensor. The optical path extender may include a photonic component configured to simulate an extension of the geometric path within an optical proximity sensor by applying a momentum-dependent transfer function to the light traveling through it.

A portable electronic device is operable in a particulate matter concentration mode where the portable electronic device uses a self-mixing interferometry sensor to emit a beam of coherent light from an optical resonant cavity, receive a reflection or backscatter of the beam into the optical resonant cavity, produce a self-mixing signal resulting from a reflection or backscatter of the beam of coherent light, and determine a particle velocity and/or particulate matter concentration using the self-mixing signal. The portable electronic device is also operable in an absolute distance mode where the portable electronic device determines whether or not an absolute distance determined using the self-mixing signal is outside or within a particulate sensing volume associated with the beam of coherent light. If not, the portable electronic device may determine a contamination and/or obstruction is present that may result in inaccurate particle velocity and/or particulate matter concentration determination.

An earbud includes a housing, a speaker mounted within the housing, a processor mounted within the housing, a user input surface on the housing, and a set of self-mixing interferometry (SMI) sensors mounted within the housing. The set of SMI sensors includes a first SMI sensor configured to emit a first beam of light, and a second SMI sensor configured to emit a second beam of light. The second beam of light passes through the user input surface about an axis that is non-perpendicular to the user input surface. The processor is configured to adjust a parameter of the speaker at least partly in response to a first SMI output of the first SMI sensor and a second SMI output of the second SMI sensor.

A sensor system includes a self-mixing interferometry sensor; a drive circuit configured to apply a modulated drive signal to an input of the self-mixing interferometry sensor; a mixer circuit configured to mix a modulated output of the self-mixing interferometry sensor with a local oscillator signal that is orthogonal to the modulated drive signal over a period of time; an integrator circuit configured to integrate an output of the mixer circuit over the period of time; and a processor configured to determine, using an output of the integrator circuit, at least one of a round-trip propagation time of electromagnetic radiation emitted by the self-mixing interferometry sensor and reflected back into the self-mixing interferometry sensor by an object or medium, or a velocity of the object or medium.

A method and system to implement the method of measuring a change in an optical path length using differential laser self-mixing interferometry. The method includes obtaining a reference SMI signal (Sr) and a main measurement SMI signal (Sm) of a laser (LD) and determining the relative change in the optical path length between the (LD) and a target (T) in a range between 0 and λ/2, by comparing the relative positions along time of fringes or transitions of the (Sm) and (Sr). The (Sr) and the (Sm) are obtained at different moments once backscattered laser light (br) is generated from the reflection on said target (T) of a reference and a main measurement laser light beam emitted by the laser (LD) and while being modulated according to a specific modulation pattern that maintained while both the (Sr) and the (Sm) are acquired and has re-entered its laser cavity.

A method for checking vital parameters. A quantitative determination of distance and/or thickness of components of the eye is performed on the basis of data of a laser feedback interferometry measurement of a human eye. A change of at least one vital parameter is ascertained in the ascertainment of a change over time of a determined distance and/or of a determined thickness of a component of the eye. The components of the eye comprising at least a cornea and/or an iris and/or a pupil and/or a lens and/or a vitreous body and/or a retina. The vital parameter comprising an eye pressure and/or a high blood pressure and/or an arteriosclerosis and/or a metabolism and/or an abnormality of the retina in terms of color or topography and/or a blood clot. A device for checking vital parameters is also described.

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.

An eye accommodation distance determining device is provided. The eye accommodation distance determining device includes an interferometer configured to generate a plurality of frequency modulated laser beams in different directions and to generate a plurality of interferometric signals using laser beams reflected from eye reflecting surfaces, a signal processer configured to generate a signal spectrum using each of said plurality of interferometric signals, a distance determiner configured to determine distances to the eye reflecting surfaces for each of said plurality of frequency modulated laser beams, a point coordinates determiner configured to determine coordinates of points on each of the eye reflecting surfaces for each of the laser beams, a reconstructor configured to generate an eye inner structure model based on the determined coordinates of points, and an eye accommodation distance determiner configured to determine, based on said eye inner structure model, an eye accommodation distance.

A sensor system includes a self-mixing interferometry sensor; a drive circuit configured to apply a modulated drive signal to an input of the self-mixing interferometry sensor; a mixer circuit configured to mix a modulated output of the self-mixing interferometry sensor with a local oscillator signal that is orthogonal to the modulated drive signal over a period of time; an integrator circuit configured to integrate an output of the mixer circuit over the period of time; and a processor configured to determine, using an output of the integrator circuit, at least one of a round-trip propagation time of electromagnetic radiation emitted by the self-mixing interferometry sensor and reflected back into the self-mixing interferometry sensor by an object or medium, or a velocity of the object or medium.

An electro-optical system has a laser drive electronic circuit, a laser light source and an optical interferometer, forming a closed loop. The laser drive electronic circuit is arranged to receive a reference frequency as input, and a beat frequency as feedback. The laser drive electronic circuit generates a drive output based on a phase difference between the reference frequency and the beat frequency. The optical interferometer, coupled to the laser light, generates optical energy at the beat frequency.