Abstract: An optical imaging system includes a first lens having a positive refractive power, an image-side surface of the first lens being concave, a second lens, a third lens, an image-side surface of the third lens being concave, a fourth lens, a fifth lens, an image-side surface of the fifth lens being concave, and a sixth lens having a positive refractive power and having an inflection point formed on an image-side surface, wherein an F number of the optical imaging system is lower than 2.2.

Abstract: Provided is a zoom lens that may achieve satisfactory optical performance from a wide angle position to a telephoto position and may be miniaturized. The zoom lens includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent group including a plurality of lens groups and having a positive refractive power, wherein the first lens group, the second lens group, and the subsequent group are sequentially arranged from an object side. Since an image plane lens group located closest to an image plane side has a zooming function, a total length of the zoom lens may be reduced.

Abstract: The optical imaging lens includes five lens elements from an object side to an image side. The optical imaging lens shows better optical characteristics through controlling the convex or concave shape of the surfaces of the lens elements to allow the thicknesses of the second and third lens elements and air gaps between the five lens elements along the optical axis satisfying the relations 1.715?AAG/(AG45)?7.593 and 2.124?ALT/(T2+T3)?3.937, where AAG is the sum of all four air gaps from the first to the fifth lens element along the optical axis, AG45 is an air gap between the fourth and fifth lens elements along the optical axis, ALT is the sum of thicknesses of the first to fifth lens elements along the optical axis, and T2 and T3 are the respective thickness of the second and third lens elements along the optical axis.

Abstract: An optical imaging lens includes first, second, third, fourth and fifth lens elements arranged sequentially from an object side to an image side along an optical axis. The image-side surface of the first lens element comprises a convex portion in a vicinity of its periphery. The third lens element has negative power. The object-side surface of the fifth lens element comprises a concave portion in a vicinity of its periphery. The optical imaging lens as a whole has only the five lens elements having refractive power.

Abstract: Provided are an optical lens assembly and an electronic device. The optical lens assembly includes a first lens having a negative refractive power, a second lens having a positive refractive power, a third lens having a negative refractive power, and a last lens having a negative refractive power. The first lens, the second lens, the third lens, and the last lens may be sequentially arranged from an object side to an image side of an optical axis, the object side facing an object for image capture and the image side facing an image plane of an image sensor.

Abstract: An optical lens assembly includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, all of which are arranged in sequence from an object side to an image side along an optical axis. The first lens is with positive refractive power and includes a convex surface facing the object side. The second lens is with refractive power. The third lens is with refractive power and includes a concave surface facing the object side. The fourth lens is with positive refractive power. The fifth lens is with positive refractive power. The sixth lens is with positive refractive power. The optical lens assembly satisfies 10?f4/f?25, wherein f4 is an effective focal length of the fourth lens and f is an effective focal length of the optical lens assembly.

Abstract: An imaging lens includes an aperture stop; a first lens having positive refractive power; a second lens having negative refractive power; a third lens; a fourth lens; a fifth lens having negative refractive power; and a sixth lens, arranged in this order from an object side to an image plane side. A surface of the first lens on the image plane side has a positive curvature radius. A surface of the third lens on the image plane side has a positive curvature radius. A surface of the fifth lens on the object side and a surface of the fifth lens on the image plane side have inflection points and are aspheric. A surface of the sixth lens on the object side has a positive curvature radius. The first to the third lenses have specific thicknesses so that specific conditional expressions are satisfied.

Abstract: An imaging lens (PL) has an image surface (I) curved to have a concave surface facing an object and consists of, in order from the object along an optical axis (Ax): a front group (Ga) including four lenses (L1 to L4); and a back group (Gb) including a single lens (L5). The following conditional expression is satisfied. 0.25<Dab/TL<0.50 0.30<La/TL<0.55 where, Dab denotes a distance between the front group (Ga) and the back group (Gb) on the optical axis, La denotes a length of the front group (Ga) on the optical axis, and TL denotes a total length of the imaging lens (PL) (a distance between a vertex of a lens surface closest to the object and an axial image point corresponding to an infinite distant object).

Abstract: An optical lens includes a first lens group with negative refractive power, a second lens group with positive refractive power, and an aperture stop disposed between the first lens group and the second lens group. A number of lenses with refractive power of the first lens group is smaller than three, and a number of lenses with refractive power of the second lens group is smaller than five. The second lens group has a lens with a diffractive optical surface, and the lens with a diffractive optical surface satisfies the condition: 0<|(?d*V)/?r|<2, where ?d denotes refractive power of the diffractive optical surface, ?r denotes refractive power of the lens, and V denotes an Abbe number of the lens with a diffractive optical surface.

Abstract: A telephoto lens includes, from an object-side to an image-side: a first lens having a positive refractive power, wherein an object-side surface of the first lens is convex, an image-side surface of the first lens is convex; a second lens having a refractive power; a third lens having a refractive power, wherein the third lens includes plastic material, each of an object-side and an image-side surface of the third lens is aspheric; a fourth lens having a refractive power, wherein an object-side surface of the fourth lens is convex, the fourth lens includes plastic material, and each of the object-side and image-side surfaces of the fourth lens is aspheric; wherein, the telephoto lens satisfies: 0.7<TTL/f<0.95, and |f4/f|?1.2; where TTL is distance from the first lens' object-side surface to an imaging plane; f is effective focal length of the telephoto lens, and f4 is effective focal length of the fourth lens.

Abstract: An optical lens accessory used in conjunction with a terminal device equipped with two camera devices is provided, the optical lens accessory includes: an optical device including two fisheye lenses arranged in a back-to-back configuration, where directions of the two respective viewing angles associated with the two fisheye lenses are opposite to each other, and where viewing angle of each of the fisheye lenses is greater than 180° to allow each of the two fisheye lenses to independently frame a view in the respective direction of the respective viewing angle, to let the framed lights into the two camera devices; a housing device positioned outside the optical device, where the housing device is configured to support the optical device, and to isolate the framed lights from external stray light; and a fixture device configured to attach the optical lens accessory to the terminal device.

Abstract: An optical lens includes a first lens group and a second lens group. The first lens group includes a first lens, a second lens, and a third lens arranged in sequence from a magnified side towards a reduced side. Refractive powers of the first lens, the second lens, and the third lens are negative, negative and positive respectively. The third lens is a glass lens. The second lens group is disposed between the first lens group and the reduced side. The second lens group includes a fourth lens, a fifth lens, and a sixth lens arranged in sequence from the magnified side towards the reduced side. Refractive powers of the fourth lens, the fifth lens, and the sixth lens are positive, negative and positive respectively. The first lens, the second lens, the fourth lens, the fifth lens and the sixth lens are plastic lenses.

Abstract: A mid-infrared objective lens assembly (10) includes a plurality of spaced apart, refractive lens elements (20) that operate in the mid-infrared spectral range, the plurality of lens elements (20) including an aplanatic first lens element (26) that is closest to an object (14) to be observed. The first lens element (26) has a forward surface (36) that faces the object (14) and a rearward surface (38) that faces away from the object (14). The forward surface (36) can have a radius of curvature that is negative.

Abstract: An ophthalmic surgical microscope includes a beam coupler positioned along an optical path of the surgical microscope between a first eyepiece and magnifying/focusing optics, the beam coupler operable to direct the OCT imaging beam along a first portion of the optical path of the surgical microscope between the beam coupler and a patient's eye (an OCT image being generated based on a reflected portion of the OCT imaging beam). The surgical microscope additionally includes a real-time data projection unit operable to project the OCT image generated by the OCT system and a beam splitter positioned along the optical path of the surgical microscope between a second eyepiece and the magnifying/focusing optics. The beam splitter is operable to direct the projected OCT image along a second portion of the optical path of the surgical microscope between the beam splitter and the second eyepiece such that the projected OCT image is viewable through the second eyepiece.

Abstract: A zoom lens includes, in order from object-side, a fixed positive first group including three-or-more lenses, a negative second group including a unit moving toward image-side during zooming toward telephoto-end, a positive third group including a unit moving toward object-side during zooming from wide-end to telephoto-end, a negative fourth group moving during zooming and focusing, and a rear group. Focal lengths of the first group and the zoom lens at wide-end, a movement amount of a unit moving by largest amount during zooming toward telephoto-end in the second group, a largest value of position change between wide-end and telephoto-end of units moving toward an object side during zooming from wide-end to telephoto-end, refractive index for d-line of a positive lens closest to image-side in the first group, and average refractive index for d-line of positive lenses of the first group other than the positive lens are appropriately set.

Abstract: Provided is a zoom lens, including, in order from object side: a positive first unit; a negative second unit; a positive third unit; a negative fourth unit; and a positive fifth unit, in which: intervals between adjacent units are changed during zooming; the first unit is not moved in an optical axis direction for zooming, and the second, third, and fourth units are moved in the optical axis direction during zooming; the fourth unit is moved in the optical axis direction during focusing; the third unit includes, in order from the object side, a positive first subunit, and a positive second subunit, and the second subunit is moved during image stabilization in a direction having a component in a direction orthogonal to the optical axis; and focal lengths of the first, third, fourth unit, and the zoom lens at a wide angle end are appropriately set.

Abstract: Provided is a rear converter optical system which is detachably mounted on an image side of a main lens system to increase a focal length of the main lens system, in which an effective diameter ?im of an imaging area of the main lens system, an effective diameter ?cr of a lens surface closest to the image side of the rear converter optical system, a lateral magnification ?c of the rear converter optical system in the case where the rear converter optical system is mounted on the main lens system, a backfocus skc in the case where the rear converter optical system is mounted on the main lens system are appropriately set.

Abstract: Provided is a zoom lens, including, in order from object side: a positive first unit; a negative second unit; a third unit having a positive or positive refractive power; and a rear group including at least one unit, in which: the first unit is not moved for zooming, and intervals between adjacent units are changed during zooming; the first unit includes three lenses, and the second unit includes three lenses; at least two lens surfaces, among lens surfaces of lenses included in the second unit except for a lens arranged closest to the object side, have aspherical shapes; and focal lengths of the zoom lens at a wide angle end and at a telephoto end, movement amounts of the second and third units during zooming from the wide angle end to the telephoto end are appropriately set.

Abstract: An optical relay system includes four or more reflective optical elements oriented in a tilted configuration. Each of the four or more reflective optical elements is tilted about one of four or more tilt axes. Further, the four or more tilt axes are oriented to correct for aberrations induced by the tilted configuration.

Abstract: An optical system for an LED wash luminaire employing an lens with a first Fresnel functional surface and a second functional surface comprised of a plurality of out of focus microlenses in bands of different focal lengths in combination with specially shaped reflector(s) to achieve a more even light distribution on a surface area with a wide range of distances from the luminaire.

Abstract: [Object] To provide a medical observation device, a lens driving control device, a lens driving control method, a program, and a video microscope device. [Solution] A medical observation device including: an evaluation value calculation unit configured to calculate a focus evaluation value indicating a focus state of a lens for each of two or more lenses; and a movement control unit configured to specify a lens movement parameter that is common to the two or more lenses on the basis of the focus evaluation value.

Abstract: An observation apparatus includes an imaging unit that includes an imaging section and an illumination section, a driving mechanism that moves the imaging unit, a position control section, a vessel position acquisition section, an illumination control section, an imaging control section that causes the imaging section to image a sample. The illumination section includes a plurality of emitting sections configured to emit illumination light and illuminates the sample. The position control section and the vessel position acquisition section acquire position information on the imaging unit and the sample, respectively. The illumination control section selects which of the emitting sections emits illumination light and causes the selected emitting section to emit main illumination light based on the position information on the sample and the imaging unit.

Abstract: A surgical microscope has an upper face provided with a light beam outlet. An assistant scope is mounted on the light beam outlet, and is rotatable in a horizontal plane so as to direct in any direction in the plane.

Abstract: A method of generating 3D information of a sample using an optical microscope includes: varying the distance between the sample and an objective lens of the optical microscope at predetermined steps, capturing an image at each predetermined step. In one example, the method further includes: determining a characteristic of each pixel in each captured image; determining, for each captured image, the greatest characteristic across all pixels in the captured image; and comparing the greatest characteristic for each captured image to determine if a surface of the sample is present at each step. In another example, the method further includes: determining a characteristic of each pixel in each captured image; determining, for each captured image, a count of pixels that have a characteristic value within a first range; and determining if a surface of the sample is present at each step based on the count of pixels for each captured image.

Abstract: An apparatus for compressive sensing may include a filter array, a detector, and a reconstruction engine. The filter array may be configured to generate a first illumination pattern in response to a first wavelength of light and a second illumination pattern in response to a second wavelength of light. The first illumination pattern and the second illumination pattern may be projected onto an object. The detector may be configured to determine a first intensity of a first light emitted by the object in response to the first illumination pattern and a second intensity of a second light emitted by the object in response to the second illumination pattern. The reconstruction engine may be configured to generate an image of the object based at least on the first intensity, the first illumination pattern, the second intensity, and the second illumination pattern.

Abstract: A beam-scanning optical design is described for achieving up to kHz frame-rate optical imaging on multiple simultaneous data acquisition channels. In one embodiment, two fast-scan resonant mirrors direct the optical beam on a circuitous trajectory through the field of view, with the trajectory repeat-time given by the least common multiplier of the mirror periods. Dicing the raw time-domain data into sub-trajectories combined with model-based image reconstruction (MBIR) 3D in-painting algorithms allows for effective frame-rates much higher than the repeat time of the Lissajous trajectory. Because sub-trajectory and full-trajectory imaging are different methods of analyzing the same data, both high-frame rate images with relatively low resolution and low frame rate images with high resolution are simultaneously acquired.

Abstract: A microscope includes: a main body having: a base portion; a pillar portion vertically disposed on part of an outer edge portion of the base portion; and an arm portion extending from an end of the pillar portion to face the base portion, an opposite end of the pillar portion connecting to the base portion; an objective lens support portion provided on one side of the arm portion facing the base portion and configured to hold an objective lens that is detachable from the objective lens support portion; an observation portion provided on an opposite side of the arm portion and configured to hold an eyepiece that is detachable from the observation portion; and an optical unit configured to hold an optical element. The arm portion includes a holding portion configured to hold the optical unit at a position intersecting with an optical axis of the objective lens.

Abstract: Disclosed are a method and apparatus for tiling light sheet selective plane illumination microscopy (TLS-SPIM) with real-time light sheet optimization. The method and apparatus image multi-cellular specimens in 3D, with an improved 3D imaging ability of SPIM in resolving complex structures and optimizes SPIM live imaging performance by using a real-time adjustable tiling light sheet and creating a flexible compromise between spatial and temporal resolution. A 3D live imaging ability is provided of the TLS-SPIM by real-time imaging cellular and sub-cellular behaviors.

Abstract: A microscope apparatus includes: a light source configured to emit illumination light to illuminate a specimen; a dimming input unit configured to set and input a light amount of the light source in a predetermined dimming range; a switching unit configured to switch a first instruction value instructing the light amount of the light source to a second instruction value larger than the first instruction value when a switching signal to switch the light amount of the light source is input; and a control unit configured to control a light amount of the illumination light emitted from the light source according to the first instruction value set and input by the dimming input unit or the second instruction value obtained by switching by the switching unit.

Abstract: A microscope includes a stage on which a specimen is configured to be placed, an epi-illumination optical system having a fluorescence illumination light source configured to irradiate the specimen with excitation light of a predetermined wavelength, a transmitted-light illumination optical system, and a light shielding member. The transmitted-light illumination optical system includes a transmitted-light illumination light source having a white LED, and a condenser having a condenser lens configured to collect light emitted from the transmitted-light illumination light source onto the specimen and configured to move in a direction orthogonal to an illumination optical path so as to be insertable onto and removable from the illumination optical path.

Abstract: A specimen observation apparatus includes: a light source; an illumination optical system; a stage; an imaging optical system; and a reflection member disposed at a position opposed to the imaging optical system across the stage. The illumination optical system is disposed so as to apply illumination light from the light source to a specimen. The imaging optical system is disposed at a position at which the illumination light that is transmitted through the specimen and thereafter reflected by the reflection member to be transmitted through the specimen again enters, and is configured to form an optical image of the specimen. The optical image is formed in a state in which a position of the specimen and a focus position of the imaging optical system are different from each other.

Abstract: Disclosed is a monocular microscope for producing a 3D image of a target having fine size. The monocular microscope includes a first imaging lens assembly; a half mirror (H) reflecting some of beams passing through the first imaging lens assembly, and transmitting remaining thereof; a first camera including a third imaging lens assembly forming an image by using the beams reflected by the half mirror (H); and a second camera including an additional third imaging lens assembly forming an image by using the beams transmitted through the half mirror (H). The monocular microscope can produce the 3D image of the target that is very close to the monocular microscope.

Abstract: A method of generating 3D information includes: varying the distance between the sample and an objective lens of the optical microscope at pre-determined steps, capturing an image at each pre-determined step; determining a characteristic value of each pixel in each captured image; determining, for each captured image, the greatest characteristic value across all pixels in the captured image; comparing the greatest characteristic value for each captured image to determine if a surface of the sample is present at each pre-determined step; determining a first captured image that is focused on a first surface of the sample based on the characteristic value of each pixel in each captured image; determining a second captured image that is focused on a second surface of the sample based on the characteristic value of each pixel in each captured image; and determining a first distance between the first surface and the second surface.

Abstract: A method of generating 3D information including: varying the distance between the sample and an objective lens of the optical microscope at pre-determined steps; capturing an image at each pre-determined step; determining a characteristic value of each pixel in each captured image; determining, for each captured image, the greatest characteristic value across a first portion of pixels in the captured image; comparing the greatest characteristic value for each captured image to determine if a surface of the sample is present at each pre-determined step; determining a first captured image that is focused on an apex of a bump of the sample; determining a second captured image that is focused on a first surface of the sample based on the characteristic value of each pixel in each captured image; and determining a first distance between the apex of the bump and the first surface.

Abstract: A stereo image pickup unit includes a first image pickup device configured to receive a first optical image formed by a first objective optical system, a second image pickup device configured to receive a second optical image formed by a second objective optical system, a single centering glass that is disposed on optical paths of the respective first and second optical images and to which light receiving surfaces of the respective first and second image pickup devices are positioned and fixed through bonding, and a holding frame that holds the first and second image pickup devices through the centering glass.

Abstract: Near-to-eye systems and head-mounted displays and more particularly but not exclusively to an optimized freeform wedge-shaped prism design having free-form surfaces efficiently mathematically represented and configured to provide both high resolution and a large exit pupil heretofore unachieved.

Abstract: A shutter assembly includes a first shutter blade having a first toothed arm extending therefrom and a first light transmitting aperture therein, and a second shutter blade positioned adjacent and parallel to the first shutter blade. The second shutter blade has a second toothed arm extending therefrom and a second light transmitting aperture therein. The first and second shutter blades are supported to allow parallel linear motion. A motor gear is disposed between, and meshed with, the first and second toothed arms such that rotation of the gear causes the first and second shutter blades to move linearly in opposite directions between an open position in which the first and second light transmitting apertures are in an overlapping relationship with respect to one another, and a closed position in which the first and second light transmitting apertures are in a non-overlapping relationship with respect to one another.

Abstract: An optical scanner comprises a light source and an MEMS mirror. The light source emits a light beam. The MEMS mirror has a reflecting surface for reflecting the light beam coming from the light source. The light source is configured in such a manner that the optical axis of the light beam vertically irradiates the reflecting surface of the MEMS mirror at a specific position.

Abstract: One embodiment provides an imaging lens comprising at least a first lens to a fourth lens which have refractive power and are disposed in order from an object-side to an image formation-side, wherein a protection lens is disposed on the front surface of a first surface of the first lens, the first surface being in the direction of the object-side, wherein the protection lens has a thickness of 1.2 millimeters or less and an effective size of 22 millimeters or more; the diameter thereof in the direction of the object-side is greater than the diameter thereof in the direction of the image formation-side; and the protection lens is disposed within 3 millimeters from the first lens.

Abstract: Various embodiments are directed to an apparatus and methods of forming and/or using an apparatus comprising a plurality of device components. An example method includes geometrically optimizing a periodic or aperiodic device comprising a plurality of device components by optimizing a topology, for each device component, from a starting point to have particular optical properties for a particular optical response. Each device component includes a plurality of geometric structures. The optimization includes selecting the starting point for a continuous profile to have the particular optical properties for the particular optical response, iteratively converging the continuous profile to a discrete profile, and, while iteratively converging to the discrete profile, adjusting edges between boundaries of the device components by accounting for fabrication constraints.

Abstract: An ambient light blocker that may include an array of spatial filters of microscopic width and microscopic length; and transparent elements that are surrounded by the spatial filters of the array and are of microscopic width.

Abstract: Systems, devices, and methods for laser projectors with variable luminance that are well-suited for use in a wearable heads-up display (“WHUD”) are described. Such laser projectors include a laser light source(s) and a scan mirror(s) to generate an image in the field of view of a user, and a liquid crystal element between the light source(s) and the scan mirror(s) to adjust the luminance of the image. The liquid crystal element is on an optical path between the laser light source(s) and the scan mirror and is communicatively coupled to a controller that modulates an opacity of the liquid crystal element. The opacity of the liquid crystal element determines the luminance of the image and may be altered in response to different factors, such as ambient light. Particular applications of the laser projector systems, devices, and methods in a wearable heads-up display are described.

Abstract: One embodiment of the invention provides a head up display (HUD) apparatus for a vehicle, comprising a display surface, and a light source including one or more narrow band emitters for directing light towards the display surface and forming an image. At least part of the display surface is selectively more reflective at wavelengths corresponding to wavelengths of light emitted by the one or more narrow band emitters for a given angle of incidence relative to other wavelengths in the visible part of the spectrum at the same angle of incidence.

Abstract: [Problem] Provided is a see-through layered body which allows obtaining a projection type image display transparent screen with a wide viewing angle, and excellent image clarity and transparency. [Solving means] A see-through layered body according to the present invention comprises an intermediate resin film, two transparent substrates holding the intermediate resin film, wherein the intermediate resin film comprises a resin and from 0.0001 to 15% by mass of microparticles, having an average diameter of from 1 nm to 100 ?m, and the center plane average roughness SRa of outermost surfaces on both sides of the layered body is from 0.05 to 5.5 nm.

Abstract: A head-up display projects an image on a transparent reflective member to allow an observer to visually recognize a virtual image. The head-up display includes a display device and a projection optical system. The projection optical system includes a refractive optical system and a concave mirror. The display device displays the image. The projection optical system projects the image displayed on the display device to a visual point of an observer. The refractive optical system includes at least one optical element. The concave mirror has a concave reflection surface. The refractive optical system is positioned on an optical path between the display device and the concave mirror. In the refractive optical system, an incident surface of a lens element having negative power into which light of the image displayed on the display device is incident is concave.

Abstract: A panel opening/closing device includes: a support which supports a panel and is turnable about a first rotary shaft; a dial which is turnable about a second rotary shaft in accordance with an operation by a user; and a movable unit which undergoes horizontal movement and includes pins inserted into a groove of the dial and a groove of the support, respectively.

Abstract: A system for and method of projecting augmentation imagery in a head-mounted display is disclosed. A system for projecting light onto an eye includes a display to project light, a beam combiner, first and second optical systems between the display and the beam combiner along respective first and second optical paths. The first and second optical paths differ. The system also includes a switchable reflector that, in a reflective state, reflects light incident upon the reflector, and, in a non-reflective state, transmits light incident upon the reflector. The reflector is between the display and the first and second optical systems along the first and second optical paths and directs light along the first path, in the reflective state, or along the second path, in the non-reflective state, to reflect light from the beam combiner to the eye from different directions when in the different states.

Abstract: The embodiments provide a head up display device comprising: at least one light source for emitting light; a first optical member for changing the path of light emitted from the light source; an optical sheet for transferring light emitted from the first optical member to a second optical member described below; and the second optical member for changing the path of light transferred from the optical sheet, and including a first surface in the direction of the optical sheet and a second surface in the direction of an image panel described below, wherein the first surface and the second surface are both curved surfaces.

Abstract: The image display device according to the present invention has a display element for displaying an image, and an eyepiece optical system for leading image light from the display element to the pupil of an observer. The eyepiece optical system has a prism and a volume-phase-type holographic optical element, and the holographic optical element is in contact with the prism. The prism surface in contact with the holographic optical element comprises a conical surface, and the prism surface on which the image light from the display element is first incident comprises a conical surface.

Abstract: Augmented reality systems and methods for automatically repositioning a virtual object with respect to a destination object in a three-dimensional (3D) environment of a user are disclosed. The systems and methods can automatically attach the target virtual object to the destination object and re-orient the target virtual object based on the affordances of the virtual object or the destination object. The systems and methods can also track the movement of a user and detach the virtual object from the destination object when the user's movement passes a threshold condition.