An encoder includes rotatable plate including first and second patterns, light emission unit, and light receiving unit. The first pattern includes first and second unit regions. The first unit regions guide the light from light emission unit to the light receiving unit. The second unit regions are configured not to guide light from the light emission unit to the light receiving unit. The second pattern includes first and second unit regions. The first unit regions of the second pattern guide light from light emission unit to the light receiving unit. The second unit regions of the second pattern are configured not to guide light from the light emission unit to the light receiving unit. The first and second unit regions of the first pattern are reverse to the first and second unit regions of the second pattern in a direction perpendicular to a rotation direction of the rotatable plate.

An encoder includes rotatable plate including first and second patterns, light emission unit, and light receiving unit. The first pattern includes first and second unit regions. The first unit regions guide the light from light emission unit to the light receiving unit. The second unit regions are configured not to guide light from the light emission unit to the light receiving unit. The second pattern includes first and second unit regions. The first unit regions of the second pattern guide light from light emission unit to the light receiving unit. The second unit regions of the second pattern are configured not to guide light from the light emission unit to the light receiving unit. The first and second unit regions of the first pattern are reverse to the first and second unit regions of the second pattern in a direction perpendicular to a rotation direction of the rotatable plate.

A system and method for monitoring rotation of a nut or bolt. The system comprises an indicator for mounting to the nut or bolt and which is configured to rotate with the nut or bolt. The system further comprises a detector configured to detect a rotational position of the indicator, and a transmitter (242) configured to transmit data indicative of the detected rotational position of the indicator.The method comprises mounting an indicator to the nut or bolt such that the indicator rotates therewith, detecting, by a detector, a rotational position of the indicator - (442), and transmitting, by a transmitter, data indicative of the rotational position of the indicator.

The present application discloses implementations that relate to devices and techniques for sensing position, force, and torque. Devices described herein may include a light emitter, photodetectors, and a curved reflector. The light emitter may project light onto the curved reflector, which may reflect portions of that projected light onto one or more of the photodetectors. Based on the illuminances measured at the photodetectors, the position of the curved reflector may be determined. In some implementations, the curved reflector and the light emitter may be elastically coupled via one or more spring elements; in these implementations, a force vector representing a magnitude and direction of a force applied against the curved reflector may be determined based on the position of the curved reflector.

There is provided a system for determining multiple baselines for detecting events in a conduit. The system comprises an optical fiber interrogator for interrogating optical fiber; and one or more processors communicative with the optical fiber interrogator and memory having stored thereon computer program code configured, when executed by the one or more processors, to cause the one or more processors to perform a method. The method comprises, for each of multiple channels of the conduit, each channel comprising a portion of the conduit: obtaining phase data for the channel, the phase data being obtained by causing the optical fiber interrogator to interrogate optical fiber positioned alongside the conduit; and determining one or more baselines from the phase data. As a result, events in the conduit may be detected with fewer false positives.

A measurement device for a linear stage includes a two-dimensional grating and a measurement unit respectively disposed on first and second moving stages of the linear stage. The measurement unit includes a light source, a two-dimensional sensor and a processor. The light source emits incident light to the two-dimensional grating so that the incident light is reflected thereby to result in reflection light. The two-dimensional sensor receives the reflection light and converts the same to a reflection signal. The processor receives the reflection signal and determines accordingly a first rotational angle, and first and second displacement components of a displacement of the first moving stage.

A light-emitting unit includes: a light source; and a reflector having reflection faces of first and second partial paraboloids, the first and second partial paraboloids being spaced from each other in an optical axis direction of the light source, the first and second partial paraboloids having a focal point on the light source, wherein: the second partial paraboloid is between the light source and the first partial paraboloid in the optical axis direction; the second partial paraboloid has a coefficient different from that of the first partial paraboloid; and the second partial paraboloid is positioned on a reflection direction side of a light from the light source reflected by the first partial paraboloid, with respect to a plane that is obtained on a presumption that the first partial paraboloid is extended to the light source side in accordance with the coefficient of the first partial paraboloid.

An electronic device is described. The electronic device may include a housing, a rotatable crown, and a self-mixing interferometry (SMI) sensor positioned within the housing. The rotatable crown may include an array of retroreflective surface features that reflect incident light back to a light source. Each retroreflective surface feature of the array of retroreflective surface features may be formed as a corner-cube with three perpendicular faces. The SMI sensor or associated processing electronics may compare originally emitted light with reflected light to identify a movement or distance of the rotatable crown with respect to the SMI sensor.

An optical detecting device includes a reflecting element, a main body, a light source and a plurality of photosensitive elements. The reflecting element has a reflecting surface. The main body has an installing, surface. The installing surface at least partially faces to the reflecting surface. The main body is configured to move along, a moving direction relative to the reflecting element. The moving direction is substantially parallel with the reflecting surface. The light source is disposed on the installing surface and is configured to emit a light ray towards the reflecting surface. The photosensitive elements are disposed on the installing surface. Sides of the photosensitive elements close to the light source surround the light source to form a light source region. The light source is at least partially located in the light source region.

A rotational position sensor assembly for detecting the selected rotational position of a rotatable selector is provided including a reference member positioned about an axis; a proximity sensor disposed on the reference member; a rotatable selector defining an inner surface, the rotatable selector mounted about the reference member and rotatable about the axis, the inner surface and the proximity sensor defining a gap there between, wherein the gap varies with respect to the rotational position of the rotatable selector, the proximity sensor generating a signal proportional to the size of the gap; and a processor and a non-transitory computer readable storage medium, the computer readable storage medium including instructions executable by the processor to receive the signal proportional to the size of the gap from the proximity sensor; and correlate the signal with a rotational position of the rotatable selector.