Abstract: An apparatus (100) and method (200) that detects the position of media (116) in a media path is disclosed. The apparatus may include a media transport (110) configured to transport media and an optical transmitter (140) coupled to the media transport, where the optical transmitter can be configured to transmit light (122). The apparatus may also include a concave reflector (130) coupled to the media transport and optically coupled to the optical transmitter, where the concave reflector can be configured to reflect light from the optical transmitter. The apparatus may further include an optical receiver (140) coupled to the media transport, the optical receiver configured to receive light (132) from the optical transmitter reflected off the concave reflector. The apparatus may additionally include a controller (160) configured to determine a position of the media based on the received light from the optical transmitter reflected off the concave reflector.

Abstract: A method and apparatus for aligning and positioning a surface such that the optical and/or cylinder axis of the surface is precisely aligned with a fixture for the purpose of assembly or further mechanical operations such as machining and polishing. According to another aspect of the invention, a lens apex is located and precisely positioned a constant distance from a reference point. In order to implement the above, a method and apparatus is disclosed for optically aligning and positioning surfaces using a precision laser displacement measurement device, an X-Y-Z micron stage, and a microprocessor (or computer) capable of performing curvature analysis.

Abstract: Method and apparatus (1a) for optical detection of the position of large-area printed products (10). The apparatus (1a) has conveyance means (2a) for movement of the printed products (10) along a conveyor path (4) past at least one contrasting light source (30), and at least one optical sensor (16). The conveyance means (2, 2a), the contrasting light source (30) and optical sensor (16) are arranged such that the printed products (10) can be conveyed between the contrasting light source (30) and the optical sensor (16).

Abstract: Methods are disclosed wherein the structural health of a civil structure, such as, but not limited to, a bridge or the like is measured by electronic distance measurement from a plurality of stable locations to a plurality of cardinal points on the structure in a methodical manner. By measuring the coordinates of the cardinal points, the dynamic and long-term static behavior of the structure provide an indication of the health of the structure. Analysis includes; comparison to a Finite Element Model (FEM), comparison to historical data, linearity, hysteresis, symmetry, creep, damping coefficient, and harmonic terms.

Abstract: The invention relates to a focusing and positioning ancillary device for a particle-optical scanning microscope, a particle-optical scanning microscope including a corresponding positioning aid, and a method for focusing and positioning an object in a particle-optical scanning microscope. The focusing and positioning ancillary device includes an illuminating device, a camera, a display and a control unit. The illuminating device produces a collimated or focused light beam at an angle to the particle-optical beam axis which intersects the particle-optical beam axis at a predetermined position. The camera is sensitive to the wavelength of the light beam and records an image of the object, which is positioned on the object table, at a second angle to the particle-optical beam axis. The control unit produces an image captured by the camera on the display together with a marking which indicates the position of the particle-optical beam axis in the image.

Abstract: A method for gesture recognition in an optical system using a touchless slider is shown. The touchless slider has first and second reference points positioned along an axis in an optical system. The method includes obtaining a plurality of first and second reflectance values by measuring an amplitude of light reflected from an object relative to the first and second reference points, respectively, wherein each first and second reflectance value corresponds to a different point in time. The plurality of first and second reflectance values are compared to identify a plurality of ratio values between the first and second reflectance values, wherein each of the plurality of ratio values corresponds to one of the points in time. At least one of a position and a direction of movement of the object relative to the first and second reference points is determined based on the identified plurality of ratio values.

Abstract: The invention relates to a measuring head system (1) for a coordinate measuring machine, having a scanning element (6), which has a part provided for contacting a measured object as a contacting part (5), which can be moved in relation to a fixed measuring head base (2) in a lateral x direction (20) and a lateral y direction (21), such that an object to be measured can be mechanically scanned using the scanning element (6). An optical sensor (10), having a sensor line (11) which can be read out and comprises a plurality of array sensor elements, is fixed on the measuring head base (2). Furthermore, means are provided, which are particularly disposed spatially fixed to the contacting part (5), generate a projection—as a function of displacements of the contacting part (5) in relation to the measuring head base (2)—on the sensor line (11) using at least one radiation source (15). In addition, an analysis unit is provided.

Abstract: A position-determining apparatus, such as measuring or surveying instruments, is disclosed. In at least one embodiment, the present invention relates to a tilt sensor for a measuring instrument including a movable housing that is controllably rotatable around a rotational axis, wherein the rotational axis may be positioned so that it deviates from a true vertical axis being parallel with a gravitational axis. In at least one embodiment, the tilt sensor includes a gravity sensitive gradient indicating element arranged such that a surface of the element is positioned orthogonally to the true vertical axis during movements of the measuring instrument, wherein the gravity sensitive gradient indicating element is arranged in connection to the non-rotating base; and a detecting device adapted to produce at least one detecting signal and to receive at least one response signal, wherein a deviation between the rotational axis and the true vertical axis is detectable using the at least one response signal.

Abstract: An optical sensor (600) for detecting the movement of an object relative to the position of the optical sensor (600), using self-mixing interference, is described. The optical sensor (600) comprises a laser (100), a detector (200) and a filter device (500). The filter device (500) suppresses measurement signals generated by means of the detector (200) when movements of the object at a velocity below a defined threshold value cause the measurement signals. The optical sensor (600) may be used in a switch in order to enable selective switching depending on the velocity of the movement of the object.

Abstract: A method is disclosed whereby a laser-based spherical coordinate measurement system is dynamically calibrated. A mechanical oscillator, such as, but not limited to, a Foucault pendulum is used to generate periodic motions which can be fitted to Fourier series models. The residuals between the experimental measurements and the model can provide information which can be used to calibrate the instrument. The calibration information is used to augment the ASME B89.4.19-2006 standard to improve sensitivity to cyclic errors and include the servo systems.

Abstract: The present invention relates to an arrangement for measuring relative movement. The measuring arrangement comprises a light source (110, 210) for emitting a light beam, a moving element (120, 220) having a reflective surface (121, 221) adapted to reflect a first wavefront portion of the light beam, and a reference element (130, 230) having a reflective surface (131, 231) adapted to reflect a second wavefront portion of the light beam. The arrangement further comprises detecting means (140, 240) for detecting changes in a spatial interference pattern produced by the light reflected from the moving element and the reference element, and processing means (150, 160, 250, 260) for calculating the relative movement between the moving element and the reference element from the phase change in the detected spatial interference pattern. The invention also relates to a method for measuring relative movement.

Abstract: The disclosure relates to a system and a method for light beam interrogation of an optical biosensor and for monitoring a biological event on the biosensor for use, for example, in microplate image analysis. The system and method correct pointing-errors that can be encountered, for example, in scanning label-independent-detection biosensor applications.

Abstract: Aerosol and hydrosol particle detection systems without knowledge of a location and velocity of a particle passing through a volume of space, are less efficient than if knowledge of the particle location is known. An embodiment of a particle position detection system capable of determining an exact location of a particle in a fluid stream is discussed. The detection system may employ a patterned illuminating beam, such that once a particle passes through the patterned illuminating beam, a light scattering is produced. The light scattering defines a temporal profile that contains measurement information indicative of an exact particle location. However, knowledge of the exact particle location has several advantages. These advantages include correction of systematic particle measurement errors due to variability of the particle position within the sample volume, targeting of particles based on position, capture of particles based on position, reduced system energy consumption and reduced system complexity.

Abstract: A device for measuring positions of structures (3) on a substrate (2) is disclosed, wherein the device is enclosed by a climatic chamber (30). An illumination and imaging means (6, 14) is also arranged in the climatic chamber (30). At least one loading station (32) for substrates is formed on an outer wall (30a) of the climatic chamber (30), wherein at least one transport means (34, 40) for transporting the substrates is provided within the climatic chamber (30). A means (36) for orienting the substrates (2) with respect to a coordinate system of the coordinate measuring machine (1) is provided, wherein the transport means (34, 40) deposits the substrates (2) on the means (36) for orienting.

Abstract: A reticle has a mask substrate, a test pattern established on the mask substrate having an asymmetrical diffraction grating so as to generate positive first order diffracting light and negative first order diffracting light in different diffraction efficiencies, and a device pattern adjacent to the test pattern established on the mask substrate.

Abstract: In a beam irradiation device, laser light emitted from a laser light source is entered into a mirror. An actuator pivotally moves the mirror into which laser light is entered, whereby a targeted area is scanned with the laser light. Servo light emitted from a semiconductor laser is entered into a hologram element. The hologram element is pivotally moved with the pivotal movement of the mirror. A diffraction pattern is formed on an exit surface of the hologram element. A photodetector receives servo light transmitted through the hologram element to output a signal depending on a light receiving position of the servo light. The scan width of servo light on the photodetector is increased by a diffraction function of the hologram element.

Abstract: A positioning method and a positioning system based on light intensity are provided. The positioning system comprises a lighting system, a sense feedback device and a positioning module. The lighting system comprises at least three point light sources and sequentially adjusts luminance of these point light sources to light up a target. The sense feedback device is disposed on the target and used to collect light intensity information of the light projected on the target by the lighting system. The positioning module calculates a distance between the target and each of the point light sources based on the light intensity information and calculates a positioning location of the target based on the locations of the point light sources and the distances between the target and the point light sources.

Abstract: The invention provides for surface mapping of in-vivo imaging subjects using a single camera and a moveable stage on which a subject animal for in-vivo imaging is placed. Images are taken and the stage is moved by known amounts along the optical axis, and the heights of individual features on the subject are determined through analysis of focus, given the known stage displacement. Alternatively, height of sub-regions of the subject are determined through analysis of focus. A mesh or other surface can be constructed from individual features, to provide a surface map of the subject. Accuracy of 0.5 mm or better can be attained for mice and similarly sized subjects.

Abstract: The invention relates to a sideways drift correction device for a mobile production machine comprising a removal of material and a tool for processing the removed material, having a sensor component and an evaluation component. The sensor component detects the structure of at least one part of the underground surface relative to which the production machine moves. The evaluation component determines the relative motion direction of a reference point on the production machine relative to the subsoil from the time-variable information of the underground surface, and derives steering correction information therefrom.

Abstract: A self-normalizing contour surface drilling apparatus drills holes into contour surfaces with the drill bit of the apparatus oriented normally to the contour surface. The apparatus first determines a location of a hole to be drilled and the orientation of the drill bit relative to the surface at the hole location, and adjusts the position of the drill bit so that the drill bit is positioned normally to the hole location. The apparatus then drills the hole at the location, and then repeats the process seeking out the next location for a drilled hole.

Abstract: An optical encoder includes a scale, and a detecting head which is disposed facing the scale. The scale is provided with a grating which has a predetermined optical pattern with respect to a direction of relative movement, and the detecting head is provided with a light emitting section which irradiates predetermined light to the scale, and a light detecting section which detects a movement of a pattern of light distribution formed on a light receiving surface of a photodetector, by light reflected by the grating upon being irradiated to the scale from the light emitting section. A light transmitting member is disposed on a surface of the light emitting section and the photodetector of the detecting head, toward the scale, and a light propagation controlling pattern for controlling propagation of light is disposed on a surface of the light transmitting member, facing the scale.

Abstract: A system for testing a distortion of a liquid crystal display (LCD) device can test the LCD device within a chamber in a state of being assembled perpendicular to the ground, whereby whether any distortion occurs in an internal component can be fast detected even in severe conditions of high temperature and high humidity and under an actual installation environment of a user.

Abstract: The invention relates to a light barrier for the detection of an object (2) which interrupts a beam of light (5) of the light barrier, having a sensor (4) with at least one light transmitter (4-1) for the transmission of a light beam (5) in the direction of a reflector (10); at least one light receiver (4-2) for the reception of a reflected portion of the light beam; and an evaluation unit (4-3) for the evaluation of the reflected light beam detected by the light receiver (4-2), To provide an improved light barrier which delivers an exact position determination of the object in the conveying device with a small installation and adjustment effort, it is proposed that the reflector (10) is made as a cylindrical reflector column (10) which has a plurality of retroreflecting elements (17) aligned toward the outer surface, with the diameter of the reflector column (10) being considerably smaller than the extent of the light beam (5) perpendicular to the cylinder axis so that an optically effective detection beam o

Abstract: In a work system which measures 3D information of a target object by a light-section method, high measurement precision is realized. The invention includes a robot arm, a hand position detection member which is arranged at the distal end portion of the robot arm, a slit laser projector which irradiates slit light, a camera which is fixed at a position independent of the robot arm, and senses an image of the target object, and a computer which calculates a light-section plane of the slit light based on a light-section line formed on the hand position detection member which is included in image data of the target object obtained by image sensing by the camera, and calculates the position and orientation of the target object based on the calculated light-section plane and the light-section line formed on the target object.

Abstract: A high-accuracy optical aberration correction system and method. Z-heights determined by an auto-focus tool, which would otherwise vary depending on the orientation angle of surface features or edges in the focus region of interest, and on the location of the focus region of interest in the field of view, are corrected based on a novel error calibration method. Error calibration data includes a set of Z-corrections for a range of different feature orientation angles (e.g., 180 degrees), for multiple locations in the field of view. Error calibration data may be interpolated to correspond to the location of the current focus region of interest. During auto-focus measurements, a Z-correction may be adapted for a current measurement by weighting orientation-dependent error calibration data based on a histogram of the gradient (edge) directions present in the current focus region of interest.

Abstract: A localization system includes: n+1 number of luminescent devices, where n is an integer greater than or equal to one; and a position measurement device moving in each direction of n number of axes, wherein the luminescent device includes a luminescent unit, the luminescent unit emitting a light for measurement having an intensity that varies at a predetermined time cycle, the luminescent unit also emitting a light for identification including an information representing a position of the luminescent device, the luminescent unit emitting the light for measurement and the light for identification in synchrony with a phase of those emitted by another luminescent device; and the position measurement device includes a light reception unit, a position obtaining unit, a phase computation unit, a standard luminescent device selection unit, a phase difference computation unit, and a position computation unit.

Abstract: A disclosed substrate position detection apparatus includes an imaging portion configured to take an image of a substrate subject to a position detection; a panel member provided between the imaging portion and the substrate and including a first opening that ensures a field of view for the imaging portion with respect to the substrate, the panel member having a light scattering property; a first illuminating portion configured to illuminate the panel member; and a processing portion capable of determining a position of the substrate in accordance with the image taken through the first opening by the imaging portion.

Abstract: The optical device for determining position and orientation of an object comprising a fixed part comprises a laser beam projector with sequential scan and a projection centre (O), defining the centre of a reference frame (R) in space. The projector emits, in a zone comprising at least four sensors fixed to the said object, the four sensors having a known disposition on the object. The instants at which each of the sensors provides an electrical pulse determine the angular directions of the said sensors in the reference frame, the four straight lines passing through the origin and through each of the sensors intercepting an image plane of the fixed part at four projected points. The positions in the image plane of the mappings of the four points determine a geometric shape making it possible to calculate the position and the orientation of the object in space.

Abstract: Systems and methods for detecting an obstruction in a detector surface fields are provided. In one respect, a set of lines may be projected over substantially a half of the detection area and may subsequently imaged and evaluated. Other embodiments may include a second set of lines that may be projected over substantially a second half of the detection area and may subsequently imaged and evaluated. The images may be evaluated to determine if there are breaks (e.g., an obstruction) in the projected set of lines. Based on the evaluation, the detector may provide dynamic feedback signals to a processor, which may adjust the position of the detector or provide a signal indicating an obstruction.

Abstract: A method and apparatus for tracking target objects includes a network of unidirectional sensors which correspond to nodes on the network. The sensors identify the presence of a target object, determine a first criteria for the relationship of the target object to the sensors and send a message to sensors neighboring the sensor. The message includes a unique identification of the target object and the first criteria. The sensors are ranked to determine which of the sensors should head a cluster of sensors for tracking the target object. Clusters are propagated and fragmented as the target object moves through a field of sensors.

Abstract: A method of processing semiconductor chips includes measuring locations of semiconductor dies placed on a carrier with a scanner to generate die location information, and communicating the die location information to a photolithographic stepper. The method includes aligning the photolithographic stepper with the carrier only one time, and exposing at least one of the dies on the carrier with the photolithographic stepper based on the die location information generated by the scanner.

Abstract: A device for determining the position of an object that is movable along at least one displacement direction, the or each displacement direction having assigned to it one length measuring device for measuring the position of the object along the respective spatial direction, includes: at least one scale extending along a displacement direction of the object to be measured as a first component of the respective length measuring device; a scanning head for scanning the scale as a second component of the respective length measuring device such that a change in the position of the scale with respect to the scanning head along the associated displacement direction of the object to be measured is measurable, one of the two components of the respective length measuring device being moved together with the object to be measured along the respective displacement direction when the latter is moved; and a device for determining the distance of the component of the respective length measuring device, which is movable tog

Abstract: An apparatus and a method that can be used for qualitative or quantitative determination of the three-dimensional location of two bodies relative to one another which can be used, for example, to determine the mutual position of two bodies according to angular or translational coordinates. Furthermore, the apparatus and method can be used in a measurement robot or in a coordinate measurement device. The device composed of a device for emitting a light beam which is fanned in several planes and at least three, preferably four or more, optoelectronic line sensors or linear sensors for determination of the incidence points of the light beam which has been flared in several planes on the line sensors or an upstream target surface.

Abstract: A fingerprint matching apparatus includes a fingerprint distortion detection unit for detecting whether or not a correlation object intentionally distorts the finger put on the fingerprint reading face by, for example, applying excessively large force to the finger, or dragging or rolling the finger. With this configuration, it is possible to prevent a distorted fingerprint image from flowing into the fingerprint matching apparatus and therefore the probability of accurate fingerprint correlation can be increased.

Abstract: An optical sensor device for local analysis of a combustion process in a combustor of a thermal power plant, in particular a gas turbine plant, includes at least one wavelength selective optical element exposed directly or indirectly to hot combustion gases being produced by said combustion process, the optical element including an array of nano- and/or microcrystalline fibres which are created by shear flow crystallization.

Abstract: A method of, and a device for, locating a piece with respect to a tool, utilize a measuring device for measuring a feeding speed, a driving direction and a feeding amount of the piece. The piece bears against two abutment rollers and is driven by a driving roller that is operated by a controllable motor operatively coupled to a machine numerical control apparatus. An output of the measuring device and an output of the controllable motor are both coupled to the machine numerical control apparatus.

Abstract: A system, apparatus, method, and computer program product for evaluating an object disposed on an upper surface of an object holder. At least one first frame representing a captured portion of the object is acquired, while the object holder is positioned at each of a plurality of locations. At least one second frame representing a captured portion of at least one other surface of the object holder besides the upper surface is acquired, while the object holder is positioned at each of the plurality of locations. At least one spatial characteristic associated with the captured portion of the object is determined, based on at least one of the acquired frames. A three-dimensional representation of the object can be formed based on the first frames and at least one spatial characteristic.

Abstract: A touch screen system and prismatic film includes a retroreflective substrate having a plurality of retroreflective elements having triangular cube corners. A metallized layer is disposed over at least a portion of the retroreflective elements. In one embodiment, the prismatic film includes two colored substrates mounted over the retroreflective elements. In another embodiment, a single substrate is mounted over the retroreflective elements. It is often desired that a color of the substrate(s) be chosen that is highly transparent in the infrared spectrum, but is also non-transparent in the visible light spectrum, giving the prismatic film a dark appearance. The prismatic film includes a plurality of retroreflective elements having triangular cube corners with a cant in a range between about 4 degrees in a face more parallel direction to 18 degrees in an edge more parallel direction and a cube depth between about 0.002 and 0.008 inches or with a cant of about 5.

Abstract: A system and method for tool enhancements are provided which allow users to utilize video tools in a controlled manner. The video tools balance a minimal amount of cursor positioning and “mouse clicks” against a level of video tool “customization” control desired by a user when applying the video tools. Tool construction methods using multiple mouse clicks are provided as an alternative to using drag-and-draw and one-click tools. Multi-click-plus tools give more specific information and provide a precise way to rapidly create customized tools.

Abstract: The present invention relates to a method for calibrating a grating of an encoder measurement system between two adjacent calibrated locations, the method includes moving one of a sensor object including an encoder-type sensor and a grating along the other one of the sensor object and the grating with a speed, wherein the speed is selected such that disturbances in the grating substantially extending over a distance smaller than a distance between the two calibrated locations can not or only partly be followed by the one of the sensor object and the grating, and measuring during the moving the position of the sensor object with respect to the grating at a plurality of locations between the two calibrated locations.

Abstract: Methods and devices for calculating the position of a movable device are disclosed. The device may include multiple optical detectors (ODs) and the movable device may include light sources. Optics may be above the ODs. A controller may calculate the position of the light source based on data from the ODs and properties of the optics. The device may be a game console, and the light source may be a game controller. The roles of the OD and light sources may be interchanged. The rotation of the movable device may be determined using multiple light sources and/or multiple ODs on the movable device. The movable device may calculate its position and transmit it to a console. The light sources may be modulated by time or frequency to distinguish between the light sources. There may be two or more movable devices. There may be two or more consoles.

Abstract: In non-limiting, illustrative embodiments, methods, systems, and manufacturing facilities are provided for locating components of a structure. Locations of features of components of a structure are simultaneously determined. Relative positions of the components are determined in a coordinate system of the structure.

Abstract: A system for generating position information includes a reflector, an image collection system, and a processor. The image collection system is configured to collect at least two sets of image data, where one set of image data includes a stronger indication of the reflector than the other set of image data. The two sets of image data can be collected in many different ways and may include using a retroreflector as the reflector. The two sets of image data are used to generate position information related to the reflector. In particular, position information related to the reflector is generated by taking the difference between the two set of image data. Because one set of image data includes a stronger indication of the reflector than the other set of image data, the difference between the two sets of image data gives a definitive indication of the reflector's position.

Abstract: An apparatus for measuring distances includes a lens module, a light sensor, and a calculation module. The lens module is used for imaging an object to be measured. The lens module has a focal plane which is non-vertical to the light axis thereof. The light sensor is used for receiving the image of the object through the lens module, and generating a corresponding signal accordingly. The calculation module is used for calculating the distance of the object based on a high frequency part of the signal. A relative method for measuring distances is provided as well.

Abstract: A light pipe for an optical navigation system. The light pipe includes a collection surface, a collimation surface, and a reflective surface. The collection surface is to accept incident light into the light pipe from a light source. The collimation surface is to collimate the light and to direct the collimated light to a navigation plane for detection by a navigation sensor. The reflective surface is between the collection surface and the collimation surface and is to reflect the light along a reflective path as the light travels within the light pipe from the collection surface to the collimation surface. The reflective surface has a curved geometry oriented substantially along the path of travel of the light through the light pipe. The curved geometry of the reflective path facilitates convergence of the light with respect to a first axis.

Abstract: The present invention relates to a hologram viewing arrangement, to an alignment device, to a display device, to a device for aligning first and second members and to a device for aligning an optical beam with a desired target. A hologram viewing arrangement comprising a pixellated phase mask substrate (20) and a pixellated hologram display substrate (40), wherein the hologram display substrate is arranged to store data representing at least two distinct images (3a-3d), the arrangement being such that disposing the phase mask in a first position with respect to the display substrate enables one of the at least two images to be visible and disposing the phase mask in a second position with respect to the display substrate enables another of the at least two images to be visible.

Abstract: A method for manufacturing a hydro dynamic bearing device is provided for the finishing treatment of lubricating oil after lubricating the hydro dynamic bearing device. The hydro dynamic bearing is constructed of an axial member housed in a housing, a radial bearing part for supporting the axial member in a non-contact manner in a radial direction by a hydro dynamic pressure action of the lubricating oil generated in a radial bearing clearance, and a sealing part arranged in an opening part of the housing, and the method has the step of measuring the oil-level height of the lubricating oil in the housing by a laser detector.

Abstract: An alignment method is used in implementation of electric characteristic inspection of an object to be inspected via electric contact between the object disposed on a movable mounting table and probes. The alignment method includes detecting tip positions of the probes by using the tip position detecting device, detecting the tip positions of the probes, previously detected by the tip position detecting device, by using the second imaging unit, transferring needle marks of the probes onto a soft member provided at the tip position detecting device by allowing the probes to come into contact with the soft member, detecting the needle marks of the probes formed on the soft member by using the first imaging unit, and detecting inspection electrodes of the object corresponding to the probes by using the first imaging unit.

Abstract: The present invention provides a position detection apparatus including a first obtaining unit configured to obtain imaging characteristics of an imaging optical system for a plurality of light beams, having different wavelength with each other, of the light having the wavelength width, a second obtaining unit configured to obtain optical images of a target object for the plurality of light beams, a restoration unit configured to restore optical images of the target object for the plurality of light beams by correcting, deterioration in the obtained optical images of the target object attributed to the imaging optical system, based on the obtained imaging characteristics of the imaging optical system, and a generation unit configured to generate an optical image of the target object for light including the plurality of light beams by synthesizing the restored optical images of the target object for the plurality of light beams.

Abstract: Multidirectional retroreflectors and methods of reflecting light beams from multiple directions are provided. The multidirectional retroreflectors utilize a four-mirror retroreflector with a common virtual reflection point.