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 stereo type distance recognition apparatus and method are provided. The stereo type distance recognition apparatus may include a plurality of sensors to generate a plurality of infrared (IR) signals, a communication unit to transmit the generated IR signals to an object, and a processor to compute a distance from the object, based on signals reflected from the object by the IR signals.

A screen display control method and an electronic device are provided. The method is performed by an electronic device with a camera installed under a screen. The method includes: receiving a first input of a user; controlling, in response to the first input, the camera to be in an operating state, and controlling a target region of the screen to be in an off state, where the target region is a region determined according to a field of view of the camera and position information of the camera.

Provided is a monocular vision ranging method, including: calculating a first distance between a target and a monocular camera, based on a geometric relationship between the monocular camera and the target; calculating a second distance between the target and the monocular camera, based on a size ratio of the target to a reference target in a corresponding reference image; evaluating credibilities of the first distance and the second distance, and determining weight values assigned to the first distance and the second distance, respectively, in which, the higher the credibilities are, the higher the weight values are; and calculating a final distance between the target and the monocular camera, based on the first distance, the second distance, and the weight values respectively corresponding to the first distance and the second distance. The present application may realize better, more stable, and wider target detection.

The present disclosure is a method to measure the distance between the place where the first image is acquired and the target distance after comparing and analyzing the image acquired through vision sensor with the established database. The database stores images of each section and image information by using the vision sensor. The distance measuring method analyzes the characteristics of the images transmitted by a user and the characteristics of the objects on images, compares them with the database, selects the image most similar to the corresponding image from the database, and calculates the distance to the user.

A method determines the time required for a timed up and go test and for verifying an ascertained result. A distance measuring device is provided which continuously measures the distance from a subject located in front of a chair to the backrest of the chair and which forwards the distance to a control unit. The chair is positioned in particular at a specified distance to a wall, an obstacle, or a marking. The measured distance values recorded by the distance measuring device are continuously recorded. The subject is instructed to stand up from the chair, walk forwards, in particular towards the wall, the obstacle, or the marking, and then turn around, in particular in front of the wall, the obstacle, or in the region of the marking, and sit back down on the chair. The subject carries out these instructions to the best of their ability.

According to the present invention, a measured distance is corrected in accordance with change in the surrounding environment. A distance measurement system includes: a first light-receiving unit configured to irradiate an object with one part of a split light beam as assessment light, and receive light reflected by the object to detect a target assessment beat signal; a second light-receiving unit configured to guide the other part of the split light beam as reference light to a reference optical path serving as a distance reference, and receive the reference light that has passed through the reference optical path to detect a reference optical path assessment beat signal; a distance measurement unit configured to measure a distance to the object on the basis of the target assessment beat signal and the reference optical path assessment beat signal; a temperature sensor configured to assess a temperature in the periphery of the reference optical path; and a correction unit configured to correct the measured distance on the basis of the assessed temperature.

A calibration system is provided including an aperture layer, a lens layer, an optical filter, a pixel layer and a regulator. The aperture layer defines a calibration aperture. The lens layer includes a calibration lens substantially axially aligned with the calibration aperture. The optical filter is adjacent the lens layer opposite the aperture layer. The pixel layer is adjacent the optical filter opposite the lens layer and includes a calibration pixel substantially axially aligned with the calibration lens. The calibration pixel detects light power of an illumination source that outputs a band of wavelengths of light as a function of a parameter. The regulator modifies the parameter of the illumination source based on a light power detected by the calibration pixel.

A fiber optic sensing system for determining the position of an object requires a light source, an optical fiber, a fiber optic splitter, a fiber tip lens, an optical detector and signal processing circuitry. Light emitted by the light source is conveyed via optical fiber and the splitter to the lens and onto an object, such that at least a portion of the light is reflected by the object and conveyed via fiber and the splitter to the detector. Signal processing circuitry coupled to the detector determines the position of the object with respect to the lens based on a characteristic of the reflected light. The system is suitably employed with a hydraulic accumulator having a piston, the position of which varies with the volume of fluid in the accumulator, with the system arranged to determine the position of the piston, from which the volume can be calculated.

A chuck interface that includes a mirror; an inner surface that is shaped and sized to match a portion of a sidewall of a chuck; wherein the inner surface is mechanically coupled to the mirror; and at least one interfacing element for assisting in attaching the chuck to the mirror; and wherein a difference between a thermal expansion coefficient of the chuck and a thermal expansion coefficient of the mirror does not exceed 0.5 micron*Kelvin per Meter.