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WO2010001299A2 - Capteur réfléchissant auto-mélangeur - Google Patents

Capteur réfléchissant auto-mélangeur Download PDF

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Publication number
WO2010001299A2
WO2010001299A2 PCT/IB2009/052684 IB2009052684W WO2010001299A2 WO 2010001299 A2 WO2010001299 A2 WO 2010001299A2 IB 2009052684 W IB2009052684 W IB 2009052684W WO 2010001299 A2 WO2010001299 A2 WO 2010001299A2
Authority
WO
WIPO (PCT)
Prior art keywords
laser
self
mixing
detecting
absolute value
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2009/052684
Other languages
English (en)
Other versions
WO2010001299A3 (fr
Inventor
Meng HAN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
Original Assignee
Philips Intellectual Property and Standards GmbH
Koninklijke Philips Electronics NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Philips Intellectual Property and Standards GmbH, Koninklijke Philips Electronics NV filed Critical Philips Intellectual Property and Standards GmbH
Publication of WO2010001299A2 publication Critical patent/WO2010001299A2/fr
Publication of WO2010001299A3 publication Critical patent/WO2010001299A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/0304—Detection arrangements using opto-electronic means
    • G06F3/0317—Detection arrangements using opto-electronic means in co-operation with a patterned surface, e.g. absolute position or relative movement detection for an optical mouse or pen positioned with respect to a coded surface
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/266—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light by interferometric means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/28—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with deflection of beams of light, e.g. for direct optical indication
    • G01D5/30—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with deflection of beams of light, e.g. for direct optical indication the beams of light being detected by photocells
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
    • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
    • G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
    • G01P3/486—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals delivered by photo-electric detectors
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/0304—Detection arrangements using opto-electronic means
    • G06F3/0312—Detection arrangements using opto-electronic means for tracking the rotation of a spherical or circular member, e.g. optical rotary encoders used in mice or trackballs using a tracking ball or in mouse scroll wheels

Definitions

  • the invention generally relates to the field of optoelectronic detection of movement-related parameters. More specifically, the invention relates to measurement of movement-related parameters by means of self-mixing sensors.
  • VCSEL vertical cavity surface emitting lasers
  • An efficient optical reflective sensor must be sensitive to weakly reflected light, even in the presence of high ambient light.
  • Current reflective sensors employ sophisticated light-modulation circuits to suppress influences of high ambient light.
  • the invention relates to a self-mixing reflective sensor, preferably VCSEL-based, which does not require a separate photodetector nor complicated signal- processing circuitry.
  • a self-mixing reflective sensor according to the invention is particularly suitable for detection of weak or diffuse reflected surfaces in high ambient light environments.
  • Laser self-mixing occurs if an external reflecting surface is arranged within the optical path of a laser so that an external cavity is obtained. Tuning of the external cavity results in a readjustment of the laser equilibrium conditions and thus in detectable changes in the laser output power. These changes, typically in the form of undulations or oscillations, are repetitive as a function of displacement of the external reflecting surface over a distance of half a laser wavelength. The undulation frequency is proportional to the velocity of the external reflector.
  • the measurement principle according to the invention is based on a detection of the self-mixing oscillation amplitude rather than the oscillation frequency of the self-mixing signal.
  • a laser self-mixing reflective sensor comprising
  • -a laser diode with a laser cavity -a detector for detecting the laser intensity
  • -circuitry for detecting self-mixing oscillations in the laser intensity due to laser light reflected back into the laser cavity the circuitry being connected to the detector for detecting the laser intensity
  • the corresponding method of detecting a displacement-related parameter by means of this self-mixing sensor comprises the steps of:
  • the self-mixing reflective sensor is a self-aligned interferometric device which is a general advantage over known sensors because the measurement accuracy is nearly independent of the alignment of the laser with respect to the movable surface. Furthermore, a power supply maintaining the injection current to the laser diode at a constant level may be advantageously employed so as to stabilize the emission wavelength.
  • the displacement-related parameter may be the displacement of the surface, an angle of rotation corresponding to the rotating displacement of the surface of a rotatable element or the velocity, i.e. the displacement per unit of time.
  • a coherent reflective sensor according to the invention can thus precisely measure displacement- related parameters such as the angular speed and displacement of rotating gears or wheels.
  • the beam is directed in one embodiment onto the top surface of the gear teeth, so that the intensity of the laser beam reflected back along the incident laser beam varies between an incidence of the laser beam onto the teeth and into gaps between the teeth of the gear wheel.
  • This effect can be strongly enhanced if the divergent beam of the laser diode is focused on the tips of the teeth, preferably with an integrated lens. If the focal depth is shorter than the height of the teeth, there will be a strong increase of the intensity of the reflected light if a tip of a gear wheel tooth passes through the laser beam. This strong increase can be easily detected by evaluating the absolute value of the amplitude or a related parameter such as the RMS-value or the envelope of the oscillating signal.
  • the movable surface may have a periodically varying reflectivity, so that the portion of the laser beam reflected back periodically switches its intensity due to reflection from structures having a lower and higher reflectance.
  • the surface whose movement or displacement is to be determined may be equipped with a structured film having alternating zones of different reflectance.
  • the detector circuitry for detecting a signal proportional to the absolute value of the oscillation amplitude can be designed in a simple and straightforward manner.
  • An envelope detector circuit may be set up by simply connecting a half-wave or full-wave rectifier element to a low-pass filter.
  • a self-mixing optical gear/wheel sensor according to the invention offers the unique advantage of a simple structure, a high resolution, and large tolerances to temperature and position variations.
  • the self-mixing reflective sensor according to the invention offers a greater sensitivity than conventional incoherent reflective sensors because incoherent high ambient light does not contribute to the self- mixing signals at all. Reflected light of 10 of intensity relative to the incident laser beam can be readily detected with a signal-to-noise ratio beyond 20 dB.
  • the focus size of laser diodes, particularly of single-mode VCSELs is typically much less than 1 mm, so that a high spatial resolution can be achieved.
  • the laser self- mixing reflective sensor may further comprise a threshold detector circuit connected to the detector circuitry for detecting a signal proportional to the absolute value of the oscillation amplitude, so that the threshold detector circuit outputs a signal which changes in level if the absolute value of the self-mixing oscillation or a parameter proportional thereto exceeds a predetermined threshold.
  • the signal proportional to the absolute value of the oscillation amplitude of the self-mixing oscillations is compared with a threshold level, and a signal with a first and a second signal level is generated.
  • the circuit generates the first signal level if the signal proportional to the absolute value of the oscillation amplitude is lower than the threshold, and generates the second signal level if the signal proportional to the absolute value of the oscillation amplitude is higher than the threshold.
  • a VCSEL preferably a single-mode VCSEL is used as the diode laser. This laser allows a very compact design of the sensor, particularly if the VCSEL includes a vertically integrated photodiode as a detector for the laser intensity.
  • an edge emitting laser diode may also be used.
  • the laser diode may comprise an integrated photodiode.
  • This photodiode may advantageously be used as a detector for detecting the laser intensity. It is further possible to detect the laser intensity via the driving current through the laser diode.
  • detecting the laser intensity by means of a monitoring photodiode is preferred, particularly due to the high sensitivity of this arrangement.
  • an external photodiode may be used as well.
  • the measurement of a displacement-related parameter such as a displacement or movement of the surface is particularly accurate and straightforward if a movable surface arranged within the optical path of the laser beam is used, which has a periodically varying reflectance for a reflection back along the direction of incidence of the laser beam.
  • the varying reflectance may be due to a variation of the texture and to the shape and local spatial position of the surface with respect to the incident laser beam. Due to the laterally varying structure of the movable surface, the intensity of the light reflected back into the laser cavity varies accordingly. This causes a variation of the strength, i.e. the absolute value of the amplitude of the self-mixing oscillations. An increase of the intensity of the light reflected back thus causes a burst in the oscillating signal.
  • typical digitalized photocurrent signals comprise bursts of short pulses and long intervals between pulse bursts which correspond to high and low reflective zones of the remote surface, respectively.
  • the speckle-related amplitude variation superpositioned on the self-mixing oscillations causes an additional random amplitude modulation. If the speckle effect is strong, the bursts in this case are series of oscillation pulses having random lengths.
  • the bursts can be detected with a detector circuit so as to determine the displacement-related parameter.
  • the circuitry for this detector can be held simple, involving e.g. the above-mentioned threshold detector.
  • the number of bursts directly corresponds to the displacement of the surface at the point of incidence of the laser beam.
  • the duration between bursts e.g. the duration between the onsets of the bursts corresponds to the velocity of the surface at the point of incidence.
  • the number of bursts or the period of consecutive bursts may be determined, respectively.
  • a simple counter circuit counting the number of bursts may thus be included.
  • self-mixing reflective sensors are suitable for remote detection of weak or diffuse reflective surfaces in high ambient light environments.
  • the sensors are valuable for detecting weak or diffuse reflective surfaces in high ambient light environments.
  • Gear or wheel rotation detectors based on self-mixing reflective sensors can be widely used in industrial and technical applications such as automotive sensors. Typical applications include gear sensors for automatic transmission, wheel speed sensors for anti-lock brake systems (ABS), steering wheel sensors for electronic stability programs (ESP) and sensors for global vehicle chassis control, e.g. in the form of a ball joint angle sensor or wishbone position sensor, and headlamp leveling.
  • ABS anti-lock brake systems
  • ESP electronic stability programs
  • the self-mixing reflective sensor or a multitude of such sensors may also be used in a lane departure warning system in vehicles by detecting e.g. road markings.
  • self-mixing reflective sensors can be made with much simpler circuits such as envelope or RMS detectors.
  • self-mixing gear/wheel sensors In contrast to widely used transductive sensors (Hall effect sensors, GMR sensors, capacitive sensors), self-mixing gear/wheel sensors also offer unique advantages of compact size (chip level integration), low cost (integrated photodiode, optical encoder), improved resolution (sub-mm focus size), greater sensitivity (typical signal-to- noise ratio beyond 20 dB), low power consumption (typically in the milliwatt range), and broad dynamic range, because the inventive sensor works well at both low and high angular speeds and has large tolerances to temperature and position variations as the sensor is substantially insensitive to air gap and temperature variations.
  • Fig. 1 shows a schematic setup of a self-mixing reflective sensor
  • Fig. 2 shows a self-mixing reflective sensor set up as a gear rotation sensor
  • Fig. 3 shows a self-mixing reflective sensor set up as a wheel rotation sensor.
  • Fig. 1 shows a schematic setup of a self-mixing reflective sensor 1 according to the invention.
  • the sensor 1 is based on the principle of generating a laser beam within the laser cavity of a laser diode and measuring the laser intensity by means of a photo detector during movement of the surface of a movable element which is placed within the optical path of the laser beam.
  • the surface is furnished with a laterally varying structure which causes a laterally varying reflection back along the direction of incidence of the laser beam.
  • the movement of the reflecting surface causes self-mixing oscillations in the laser intensity due to laser light reflected back from the surface into the laser cavity.
  • the oscillations are extracted by using appropriate circuitry connected to the detector for detecting the laser intensity.
  • a signal proportional to the absolute value of the oscillation amplitude of the self-mixing oscillations is determined and a displacement- related parameter is calculated therefrom.
  • a simple envelope and/or RMS detector circuitry is employed to quantify the absolute modulation amplitude of the photocurrent. This value is correlated with the local reflectivity of the surface at the point of incidence of the laser beam.
  • a single-mode VCSEL 3 is used as a laser diode.
  • the beam 9 of the VCSEL 3 is focused on the surface of a moving element 11.
  • the surface of this element 11 has a periodically varying reflectance for a reflection back along the direction of incidence of the laser beam. Specifically, regions 13 having a higher reflectance and regions 15 having a relatively lower reflectance alternate along the direction 12 of movement, indicated by an arrow. Due to this varying reflectance, the beam reflected back into the laser cavity has a higher intensity if the laser beam is incident on a region 13 as compared to an incidence on a region 15 of the surface.
  • the typical optical power of a VCSEL for reflective sensing applications is preferably kept below 1 mW.
  • the VCSEL injection current is kept at a constant level.
  • the VCSEL 3 comprises a vertically integrated photodiode 5 which is used as a photodetector.
  • the electric signal of the photodiode 5 is fed to a circuit 17 for detecting self-mixing oscillations in the laser intensity.
  • the electric signal is shown as a diagram within circuit 17. Due to interference of the generated beam with the reflected beam having a time-dependent phase shift caused by the movement of the surface of element 11, the laser intensity and hence the electric signal of photodiode 5 oscillates with a period 22 and amplitude 23 around a median value 18. Furthermore, the oscillating signal is superpositioned by a random oscillation caused by the speckle effect.
  • the laser beam hits regions 13 having a higher reflectance, whereas a region 15 having a relatively lower reflectance is scanned during the intermediate time interval 25.
  • the absolute value of the oscillation amplitude is proportional to the intensity of the reflected beam, the oscillation amplitude is higher in time intervals 24 and 26. Accordingly, bursts of the oscillation signal are observed if the laser beam sweeps across regions 13. As shown in the diagram, these bursts may have the shape of a random series of pulses due to the superposition of the speckle effect.
  • the signal is further evaluated by an envelope detector circuit 19 as detector circuitry for detecting a signal proportional to the absolute value of the oscillation amplitude.
  • the envelope signal 28 shown as a diagram within envelope detector circuit 19 reflects the course of the absolute amplitude values.
  • a RMS detector circuit may be used alternatively because the RMS signal corresponds to the absolute value of the self-mixing amplitude.
  • the sensor 1 comprises a threshold detector circuit 21 connected to the envelope detector circuit 19.
  • the threshold detector circuit 21 such as an analog-to-digital converter or comparator, compares the envelope signal with a threshold level shown as solid line 30 in the diagram of the envelope signal 28.
  • a signal 32 is output, which changes between two levels 34, 35 if the envelope signal 28 exceeds threshold 30. Accordingly, due to the superpositioned speckle effect, the threshold detector circuit 21 outputs bursts in the form of a series of switching pulses, while the beam 9 sweeps across regions 13 and the output remains at a constant level during a sweep across regions 15.
  • the output of threshold detector circuit 21 is further evaluated by a circuit 37.
  • the velocity of the surface can be determined by determining the period or frequency of the bursts.
  • the displacement of the surface within this time interval can be easily calculated.
  • Fig. 2 shows an application of the self-mixing reflective sensor 1 as a gear-wheel rotation sensor.
  • a coherent self-mixing reflective sensor 1 is used to measure the angular speed and/or displacement of a gear wheel 40 rotating about its axis 41.
  • the VCSEL beam 9 is focused on the tips of the gear teeth 42, which introduces significant modulations to the VCSEL photocurrent, similarly as shown in Fig. 1.
  • the VCSEL beam focal depth is preferably designed to be much shorter than the height of the gear teeth. Since the optical feedback strength drops rapidly as the remote surface moves out of focus, the VCSEL photocurrent modulation due to reflection of the base of the gear tooth become insignificant. Bursts of the self-mixing oscillation are thus detected, each burst corresponding to a tooth passing through the laser beam 9.
  • the lens 9 has a longer focal depth than the height of the teeth, the reflection back along the incident beam will vary considerably, because the light is deflected away from the direction of incidence at the sloped side walls of the teeth.
  • the photocurrent signal is evaluated analogously as described with reference to Fig. 1, using circuitry 44 comprising an envelope detector or RMS detector circuit and a comparator or ADC circuit.
  • This sensor may be used, for example, as a sensor in an automatic transmission system.
  • Fig. 3 shows a self-mixing reflective wheel sensor according to the invention.
  • the surface of a rotatable element such as a shaft or wheel 45 is optically encoded with alternating bright and dark areas 13, 15.
  • the reflectivity of the different areas is correlated with the modulation amplitude of the VCSEL photocurrent.
  • the rotation velocity and/or rotation angle can thus be detected to correspond to the circumferential velocity and displacement of the optically encoded surface, respectively.
  • the optically encoded surface may be provided simply by attaching a structured film 46 to the shaft or wheel 45.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Optical Transform (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

La présente invention concerne un capteur réfléchissant auto-mélangeur, de préférence à base de laser à cavité verticale émettant par la surface ou "VCSEL" (Vertical-Cavity Surface-Emitting Laser), qui ne nécessite pas la présence d'un photodétecteur distinct ni de circuits logiques de traitement du signal compliqués. Pour effectuer les mesures, l'invention procède par détection d'amplitude d'oscillation de l'auto-mélange plutôt que par détection de fréquence d'oscillation du signal d'auto-mélange.
PCT/IB2009/052684 2008-06-30 2009-06-23 Capteur réfléchissant auto-mélangeur Ceased WO2010001299A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP08104584.1 2008-06-30
EP08104584 2008-06-30

Publications (2)

Publication Number Publication Date
WO2010001299A2 true WO2010001299A2 (fr) 2010-01-07
WO2010001299A3 WO2010001299A3 (fr) 2010-10-07

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PCT/IB2009/052684 Ceased WO2010001299A2 (fr) 2008-06-30 2009-06-23 Capteur réfléchissant auto-mélangeur

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8926143B2 (en) 2013-03-13 2015-01-06 Corning Incorporated Light-diffusing elements
US9677873B2 (en) 2010-07-26 2017-06-13 Koninklijke Philips Electronics N.V. Apparatus, method and computer program for determining a distance to an object using a determined peak width of a self-mixing interference (SMI) signal
US10627961B2 (en) 2018-09-25 2020-04-21 Apple Inc. Waveguide-based interferometric multi-point/distributed force and touch sensors
US10824275B2 (en) 2018-09-25 2020-11-03 Apple Inc. Waveguide-based interferometric multi-point/distributed force and touch sensors
US11157113B2 (en) 2018-04-13 2021-10-26 Apple Inc. Self-mixing interference based sensors for characterizing touch input
CN114265077A (zh) * 2020-09-15 2022-04-01 通快光电器件有限公司 用于自混合干涉法的激光传感器模块
US11644800B2 (en) 2018-04-13 2023-05-09 Apple Inc. Coherent mixing interference based sensors for characterizing movement of a watch crown
US11674825B2 (en) 2021-09-21 2023-06-13 Apple Inc. Cylindrical retroreflector array for rotation tracking
US11740071B2 (en) 2018-12-21 2023-08-29 Apple Inc. Optical interferometry proximity sensor with temperature variation compensation
CN117665319A (zh) * 2024-01-31 2024-03-08 中国空气动力研究与发展中心超高速空气动力研究所 一种适用于强自发光自由飞模型的光电探测装置及方法
US12092996B2 (en) 2021-07-16 2024-09-17 Apple Inc. Laser-based rotation sensor for a crown of an electronic watch
US12105480B2 (en) 2018-06-25 2024-10-01 Apple Inc. Crown for an electronic watch
US12189347B2 (en) 2022-06-14 2025-01-07 Apple Inc. Rotation sensor for a crown of an electronic watch

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7268705B2 (en) * 2005-06-17 2007-09-11 Microsoft Corporation Input detection based on speckle-modulated laser self-mixing
US7543750B2 (en) * 2005-11-08 2009-06-09 Microsoft Corporation Laser velocimetric image scanning

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9677873B2 (en) 2010-07-26 2017-06-13 Koninklijke Philips Electronics N.V. Apparatus, method and computer program for determining a distance to an object using a determined peak width of a self-mixing interference (SMI) signal
US8926143B2 (en) 2013-03-13 2015-01-06 Corning Incorporated Light-diffusing elements
US11157113B2 (en) 2018-04-13 2021-10-26 Apple Inc. Self-mixing interference based sensors for characterizing touch input
US11644800B2 (en) 2018-04-13 2023-05-09 Apple Inc. Coherent mixing interference based sensors for characterizing movement of a watch crown
US12124224B2 (en) 2018-04-13 2024-10-22 Apple Inc. Sensors for characterizing movement of a watch crown
US12105480B2 (en) 2018-06-25 2024-10-01 Apple Inc. Crown for an electronic watch
US10627961B2 (en) 2018-09-25 2020-04-21 Apple Inc. Waveguide-based interferometric multi-point/distributed force and touch sensors
US10824275B2 (en) 2018-09-25 2020-11-03 Apple Inc. Waveguide-based interferometric multi-point/distributed force and touch sensors
US11392248B2 (en) 2018-09-25 2022-07-19 Apple Inc. Waveguide-based interferometric multi-point/distributed force and touch sensors
US11740071B2 (en) 2018-12-21 2023-08-29 Apple Inc. Optical interferometry proximity sensor with temperature variation compensation
CN114265077A (zh) * 2020-09-15 2022-04-01 通快光电器件有限公司 用于自混合干涉法的激光传感器模块
US12092996B2 (en) 2021-07-16 2024-09-17 Apple Inc. Laser-based rotation sensor for a crown of an electronic watch
US12104934B2 (en) 2021-09-21 2024-10-01 Apple Inc. Cylindrical retroreflector array for rotation tracking
US11674825B2 (en) 2021-09-21 2023-06-13 Apple Inc. Cylindrical retroreflector array for rotation tracking
US12189347B2 (en) 2022-06-14 2025-01-07 Apple Inc. Rotation sensor for a crown of an electronic watch
CN117665319B (zh) * 2024-01-31 2024-04-30 中国空气动力研究与发展中心超高速空气动力研究所 一种适用于强自发光自由飞模型的光电探测装置及方法
CN117665319A (zh) * 2024-01-31 2024-03-08 中国空气动力研究与发展中心超高速空气动力研究所 一种适用于强自发光自由飞模型的光电探测装置及方法

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