A device includes an electronic display, a cover through which the electronic display projects an image, and an array of SMI sensors. The array of SMI sensors is positioned on a same side of the cover as the electronic display. Each SMI sensor is configured to emit electromagnetic radiation toward a respective portion of: an interior surface of the cover, or a surface of a component of the device attached to the cover; and generate a respective SMI output including information indicative of vibration of the respective portion of the cover or the component. The device also includes circuitry configured to characterize a vibratory waveform impinging on the device. The vibratory waveform is characterized using at least two of the SMI outputs.

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.

A device includes an electronic display, a cover through which the electronic display projects an image, and an array of SMI sensors. The array of SMI sensors is positioned on a same side of the cover as the electronic display. Each SMI sensor is configured to emit electromagnetic radiation toward a respective portion of: an interior surface of the cover, or a surface of a component of the device attached to the cover; and generate a respective SMI output including information indicative of vibration of the respective portion of the cover or the component. The device also includes circuitry configured to characterize a vibratory waveform impinging on the device. The vibratory waveform is characterized using at least two of the SMI outputs.

An electronic device including an SMI sensor may be operated to predict interference in an SMI signal caused by speckle provided by the SMI sensor and operate the SMI sensor based on predicted interference in the SMI signal caused by speckle. Predicting interference in the SMI signal caused by speckle and operating the SMI sensor accordingly may allow for accurate measurement of physical phenomena using the SMI sensor with reduced power consumption.

A wearable device includes a band and a set of one or more SMI sensors. The band has a band interior opposite a band exterior, and is operable to attach the wearable device to a user. The band defines a cavity, and a portion of the band interior separates the cavity from the user. The set of one or more SMI sensors are disposed in the cavity. The set of one or more SMI sensors are configured to emit electromagnetic radiation toward the portion of the band interior and generate a set of one or more SMI signals including information indicative of movement of the portion of the band interior.

Disclosed herein are self-mixing interferometry (SMI) sensors, such as may include vertical cavity surface emitting laser (VCSEL) diodes and resonance cavity photodetectors (RCPDs). Structures for the VCSEL diodes and RCPDs are disclosed. In some embodiments, a VCSEL diode and an RCPD are laterally adjacent and formed from a common set of semiconductor layers epitaxially formed on a common substrate. In some embodiments, a first and a second VCSEL diode are laterally adjacent and formed from a common set of semiconductor layers epitaxially formed on a common substrate, and an RCPD is formed on the second VCSEL diode. In some embodiments, a VCSEL diode may include two quantum well layers, with a tunnel junction layer between them. In some embodiments, an RCPD may be vertically integrated with a VCSEL diode.

Disclosed herein are electronic devices, and methods for their operation, that identify user inputs based on interaction of an object with input surfaces separate from the electronic devices. The electronic devices may include one or more self-mixing interferometry sensors that scan a field of view containing the input surface with a light beam, such as a laser beam emitted laser diode. Self-mixing of the emitted light with reflections can generate a self-mixing interferometry signal. Analysis of the self-mixing interferometry signal can allow for identification of an object, such as a user's finger, in the field of view. Deformation of the finger can be detected with the self-mixing interferometry sensor, and a user input identified therefrom.

The invention describes a laser sensor module (100) for particle density detection. The laser sensor module (100) comprising at least one first laser (110), at least one first detector (120) and at least one electrical driver (130). The first laser (110) is adapted to emit first laser light in reaction to signals provided by the at least one electrical driver (130). The at least one first detector (120) is adapted to detect a first self-mixing interference signal of an optical wave within a first laser cavity of the first laser (110). The first self-mixing interference signal 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 laser sensor module (100) is adapted to reduce multiple counts of the particle. The invention further describes a related method and computer program product.

Aspects of the present disclosure describe Rayleigh fading mitigation via short pulse coherent distributed acoustic sensing with multi-location beating-term combination. In illustrative configurations, systems, methods, and structures according to the present disclosure employ a two stage modulation arrangement providing short interrogator pulses resulting in a greater number of sensing data points and reduced effective sectional length. The increased number of data points are used to mitigate Rayleigh fading via a spatial combining process, multi-location-beating combining (MLBC) which uses weighted complex-valued DAS beating results from neighboring locations and aligns phase signals of each of the locations, before combining them to produce a final DAS phase measurement. Since Rayleigh scattering is a random statistic, the MLBC process allows capture of different statics from neighboring locations with correlated vibration/acoustic signal. The combined DAS results minimize a total Rayleigh fade, in both dynamic fading and static fading scenarios.

Disclosed herein are wearable devices, their configurations, and methods of operation that use self-mixing interferometry signals of a self-mixing interferometry sensor to recognize user inputs. The user inputs may include voiced commands or silent gesture commands. The devices may be wearable on the user's head, with the self-mixing interferometry sensor configured to direct a beam of light toward a location on the user's head. Skin deformations or vibrations at the location may be caused by the user's speech or the user's silent gestures and recognized using the self-mixing interferometry signal. The self-mixing interferometry signals may be used for bioauthentication and/or audio conditioning of received sound or voice inputs to a microphone.