Abstract: A polaroid encoder system for detecting movement is disclosed. The system includes a movable polarizing code element. A detector module detects an amplitude based on how much illumination passes through one portion of the movable polarizing code element. A quadrant of the movable polarizing code element is determined based on how much illumination passes through another portion of the movable polarizing code element. The angular position of the movable polarizing code element can then be determined by using amplitude and the quadrant information.

Abstract: In an encoder which is equipped with two detectors arranged on both sides of a rotating shaft in order to eliminate an eccentricity error, the mounting of the detectors is facilitated by making provisions so as to not cause a problem in the calculating of an average even if the detectors happen to be so mounted that the difference between the angular values calculated from the outputs of the respective detectors becomes equal to 180°. In an initialization process after power on, the difference ?? between the angular values ?1 and ?2 calculated from the signals output from the respective detectors is stored as an initial value. Position data ? is output by taking an average between ?3 and ?2, where ?3 is a value obtained by correcting ?1 by the initial difference ??.

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: In one embodiment of the present invention, a rotary encoding switch is disclosed such as used in the function setting for relays or similar. In one embodiment, a particularly secure function setting for relays or similar may be achieved by means of a rotary encoding switch with a number of switch stages with separations between the switch stages which are not constant.

Abstract: An angle-calculation apparatus for three-phase optical encoder receives three-phase sinusoidal signals 120 degree phase from the optical encoder and obtains angle information for a motor rotor. The angle-calculation apparatus includes an A/D converter, a digital signal processor (DSP), a phase digitalizer and a digital counter. The A/D converter converts three-phase analog signals of the optical encoder into three-phase digital signals. The phase digitalizer converts the three-phase analog signals into digital phase signals. The digital counter generates a counting value based on the digital phase signals. The DSP performs an inverse trigonometric function calculation on a relatively linear region of the three-phase digital signals to obtain the angle information. The DSP obtains the rotation turn number and rotation direction of the motor rotor according to the counting value.

Abstract: An optical static and dynamic torque sensor provides a measurement of torque, torque angle, shaft speed or shaft direction by optically detecting the overlapped position of spatially arranged apertures on discs attached to input and output ends of a flexure as torque is applied to the flexure.

Abstract: A position control system configured to control the position of a movable object, includes: a position measurement system configured to determine a position of a sensor or sensor target on the movable object, a comparator configured to provide an error signal by comparing a set-point position and a position feed-back signal based on the measured position, a controller to provide a control signal based on the error signal, a feed-forward device to provide a feed-forward signal on the basis of a first signal related to the desired position, and one or more actuators configured to act on the movable object based on the control signal and the feed-forward signal, wherein the position control system further includes a compliance compensation device providing a compliance compensation signal, wherein the compliance compensation signal is subtracted from a measured position of the position measurement system to obtain the feed-back position signal.

Abstract: A manufacturing method for a code wheel for a rotary encoder is provided. The code wheel includes, in a central portion, a hole into which a rotary shaft of a rotary member is fitted and a code portion including a radial code pattern in a circumferential edge portion. The manufacturing method is configured to include the steps of forming the code portion and a reference circle in a plate so that the reference circle has a radius larger than a radius of the hole by a tolerance of deviation between a center position of the code portion and a center position of the hole and has a same center as that of the code portion; and forming the hole in the plate in which the code portion and the reference circle are formed, so as to be contained in the reference circle.

Abstract: An optical assembly comprises at least one optical element movable in at least two degrees of freedom and at least one actuator for adjusting the least one optical element; at least one sensor for sensing the position of the at least one element in at least two degrees of freedom and is characterized in that the at least one sensor is located at least substantially diagonally opposite to the least one actuator.

Abstract: An incremental encoder, which comprises a light source, a code wheel, a first photo-sensitive unit, a second photo-sensitive unit, a first inverse-phase photo-sensitive unit and a comparison circuit, is disclosed. The light source provides a detecting light. The code wheel comprises many diaphanous holes. The detecting light is sieved into a light pulse signal by the diaphanous holes when the code wheel is rotating. The first photo-sensitive unit, the second photo-sensitive unit and the first inverse-phase photo-sensitive unit generates the first electronic signal, the second electronic signal and the first inverse-phase electronic signal respectively based on the light pulse signal. The comparison circuit generates a voltage signal by composing the first electronic signal and the first inverse-phase electronic signal, generates a first digital signal based on the voltage signal and the first electronic signal, and generates a second digital signal based on the voltage signal and the second electronic signal.

Abstract: A rotary encoder includes a shaft which serves as a rotation axis, a disc supporting plate fixed to the shaft, an encoder disc having a center hole, a first side face, and a second side face opposing the first side face, an elastic member contacting and pressing the second side face of the encoder disc, and a retaining member retaining the second side face of the encoder disc via the elastic member. The first side face is contacted with a surface of the disc supporting plate. The shaft is inserted into the hole. A belt conveyance apparatus includes an endless belt, a roller configured to rotate the endless belt, including a shaft and the rotary encoder. The rotary encoder is provided on the shaft of the roller. An electrophotographic image forming apparatus includes an image forming unit and the belt conveyance apparatus.

Abstract: The present disclosure provides an apparatus and method for the measurement of the width and radial spacing of commutator segments with respect to span. The apparatus utilizes a microprocessor and computer to record and calculate data from both a rotary encoder wheel held in contact with the commutator surface as it turns, and a fiber optic sensor that recognizes commutator segment boundaries. The commutator is rotated for one revolution plus one span to improve convenience and accuracy of the measurements. Output is provided in the form of graphs and charts that show the variation in the different spans around the commutator, and information is also provided as to each bar and insulator.

Abstract: A reflective optical encoder for a gear train. The reflective optical encoder includes a gear train with a plurality of gears. Each of the gears is operably coupled to at least one other gear of the plurality of gears. A reflective code pattern is accessible on a surface of at least one of the gears. A reflective optical sensor detects light reflected by the reflective code pattern. Position logic coupled to the optical sensor determines a rotational parameter of the gear train based on the light reflected by the reflective code pattern. Additionally, the position logic may determine rotational parameter of a pinion coupled to the gear train based on the rotational parameter of the gear train.

Abstract: A high-precision absolute type encoder apparatus includes a controller electrically connected to an incremental type encoder and generating a control signal to the incremental type encoder, a comparator electrically connected to outputs of the incremental type encoder and generating first pulse signals, a latch unit electrically connected to outputs of the comparator and generating second pulse signals by latching the generating first pulse signals. When power failure occurs, the controller generates the control signal as successive pulses with predetermined period to drive the latch unit and the incremental type encoder. Therefore, the controller knows angular information of the incremental type encoder by counting the second pulse signals. The absolute angular information can be obtained by combining the angular information and an initial position after power failure.

Abstract: A method for determining the position of one of two components in relative motion with respect to each other, using optical means, comprises: directing at least one light beam emitted by a light source attached to one component towards a diffractive support attached to the second component, calculated and manufactured for generating an optical signal indicative of the positioning of said support, the optical signal being produced by the diffractive support in transmission and/or in reflection; detecting and reading at least one optical code formed by said signal, which corresponds to a unique position of the diffractive support relatively to the beam; and assigning a position to each detected optical code.

Abstract: A position-measuring device for measuring linear and/or angular positions includes at least two measuring standards on which at least one code track is applied, and includes a scanning unit for scanning the code tracks. The measuring standards are positioned with respect to each other such that at least one code track of a first measuring standard and at least one code track of a second measuring standard at least partially overlap and the position information of at least one of the code tracks is scannable by the scanning unit in the region of overlap.

Abstract: An optical encoder includes a coding element having a track with a track pattern that comprises multiple optically distinguishable sections. The optical encoder compares photodetector outputs with transition-specific thresholds that correspond to transitions between the optically distinguishable sections of the track. The comparisons are used to determine when the transition between two optically distinguishable sections of the track has passed the photodetector. Knowledge of the transition between two optically distinguishable sections is then translated into digital position information.

Abstract: An encoder device includes first through fourth photodiodes each having a rhombus shape and a length of X1 in an X direction, the photodiodes being disposed adjacent to each other in the X direction such that a line passing through a pair of opposing vertices of the rhombus shape of each of the photodiodes is parallel to an X axis; a slit member that includes light transmitting sections and light shielding sections alternately arranged, and is movable in the X direction, each of the light transmitting and shielding sections having a length of 2×X1 in the X direction; and a logic circuit that generates first and second detection signals from output signals of the photodiodes that have received lights passing through the light transmitting sections, a phase of the second detection signal being shifted by a ¼ period of the first detection signal relative to the first detection signal.

Abstract: Rotary encoder apparatus is described that comprises an encoder scale or ring and an encoder scale reader. The encoder scale includes an incremental scale and one or more reference marks. The encoder scale reader comprises at least a first readhead and a second readhead that each produce a reference mark signal when passed over a reference mark of the encoder scale. The apparatus also comprises a reference position setter for determining, as the encoder scale reader is rotated relative to the encoder scale, at least one angularly repeatable reference position of the encoder scale relative to the encoder scale reader using a first reference mark signal produced by the first readhead and second reference mark signal subsequently produced by the second readhead.

Abstract: Disclosed is a rotary device that rotatably and movably supports a rotary body, thereby reducing the number of parts, as compared to the related art. A rotary body (and a code member that is supported such that it can be rotated together with the rotary body) is supported so as to be movable in an X1-X2 direction independently from a fixed base and a fixed board. A photo interrupter is fixed to the surface of the fixed base. The interrupter is arranged such that the direction of a straight line linking the center of a light emitting portion in the width direction and the center of a light receiving portion in the width direction is orthogonal to the direction in which the rotary body is moved, and when the rotary body is positioned at the center of the movement direction, the straight line passes through a rotation center.

Abstract: An optical encoder includes an incoherent light source; a first grating, which is an amplitude grating having a first grating period, for spatial amplitude modulation of the incoherent light from the light source; a second grating, which is a phase grating having a second grating period, for spatial phase modulation of light from the first grating; a third grating, which is an amplitude grating having a third grating period, for spatial amplitude modulation of light from the second grating; and a light detecting element for detecting light from the third grating. The encoder detects relative displacement between the respective gratings. The optical transfer function from the light source to the light detecting element is enhanced, and the efficiency in utilizing light is improved.

Abstract: An optical encoder includes a code strip having a first side, a second side, a first track comprising indicia thereon, and a second track comprising indicia thereon. The code strip is moveable along a displacement path with respect to the optical encoder. A light source positioned on the first side of the code strip directs light toward the code strip. A first detector element is positioned on the second side of the code strip and is generally aligned with the first track of the code strip. A second detector element is positioned on the second side of the code strip and is generally aligned with the second track of the code strip. The second detector element is also positioned so that the second detector element is located a spaced distance along the displacement path from the first detector element.

Abstract: An optical encoder includes a coding element having a track with multiple transparent sections, a light source positioned to output light to the track, and a photodetector array, positioned to detect light that passes through the transparent sections of the track. The photodetectors of the photodetector array have larger width dimensions than the width dimensions of the transparent sections of the track. Resolution of the optical encoder may be adjusted by changing the resolution of the coding element.

Abstract: In a photoelectric encoder (incremental encoder and absolute encoder) having a detector that is displaceable relative to a scale having a predetermined pattern (incremental pattern and pseudorandom pattern) formed thereon, the detection range, to be simultaneously detected, of the pattern is divided in at least the detection direction, and a plurality of light-receiving systems are provided to detect each of the respective detection areas, whereby measurement of a wide detection range is enabled by using a small-sized and simple optical system and light-receiving system.

Abstract: An angle-measuring instrument including a cap defining an opening and a base body that is covered by the cap. A printed circuit board positioned on the base body and on which an electrical coupling element is fixed in place. A spacer that aids in positioning the cap in such a way relative to the printed circuit board so that the opening is aligned with respect to the electrical coupling element.

Abstract: A measuring instrument, in particular for transmission measurement with transparent substrates, comprises a measuring head with a light emitting element for emitting a light beam and a light receiver element for recording an incident light beam, and a retro-reflector for reflection of the emitted light beam. The measuring instrument allows transmission measurements to be carried out on transparent substrates with only one reflection measuring head. The measuring instrument also allows reflection measurements to be carried out, for example on non-transparent substrates or by tilting the measuring head and covering the retro-reflector. The measuring instrument only requires one measuring head and can therefore be produced more cost-effectively. It does not require calibration, as the retro-reflector also reflects the light in the original direction in the case of oblique incidence and in the event of positional changes caused by process or operational factors (vibrations etc.).

Abstract: A mark detector to detect a plurality of marks which are arranged in a predetermined cycle on a moving member, such as a photo conductor belt, a transfer belt, a paper conveyance belt, a photo conductor drum, a transfer drum, etc. especially in an image forming apparatus, has an optical head including a light source to irradiate a light beam, a beam shaping device to shape the light beam, and a photo acceptor to accept light from the marks. Light beams on the marks from the light source have different positions shifted within a half mark cycle of each other on the marks. This increases accuracy and stability of controlling a motion of the moving member.

Abstract: In a signal transmission device as well as a method for transmission of signals between two elements moving relative to one another, in particular for transfer of measurement and/or control data between a rotating part and a stationary part of a computed tomography apparatus, a transmission device with an RF strip conductor is used on a first of the two elements, the RF strip conductor is composed of a dielectric layer with electro-optical properties between two strips made of an electrically-conductive material, into which the signals are fed. In the method and the associated device, local temporal changes of optical properties of the dielectric layer that are electrically induced in the dielectric layer by the signals proceeding along the strip conductor are scanned with a light beam of a scanning unit arranged on the second element, at least during a movement segment of the relative movement of the two elements.

Abstract: An optical encoder that includes an optical grating and a quadrature optical encoder sensor that move relative to each other. The optical grating includes a first encoder bar and a plurality of second encoder bars, wherein the first encoder bar is optically configured to change an amplitude of an output of the quadrature optical encoder sensor.

Abstract: A system for transferring power between components includes a first object having a light emitter operatively connected to a power source, and a second object having a light receiver operatively connected to a power storage unit. The light receiver receives light emitted from the light emitter and converts the received light into electricity that is stored in the power storage unit.

Abstract: An optical encoder. The optical encoder includes a coding element, an emitter, and a detector. The coding element has a track with a track pattern. The track pattern includes a plurality of optically distinguishable sections. The plurality of optically distinguishable sections includes a limit switch section. The emitter generates a light signal incident on the track of the coding element. The detector includes a limit switch photodetector positioned to detect the light signal from the emitter. The detector generates a limit switch output signal in response to the detected light signal above a limit switch threshold at the limit switch photodetector. Embodiments of this type of optical encoder implement limit switches into a single track on the coding element.

Abstract: An optical encoder includes an optical encoder pattern of alternating light elements and dark elements, and an optical unit, including an optical emitter providing light to the encoder pattern, and an optical sensor including a photo-detector receiving the light from the optical encoder pattern and in response thereto outputting a sinusoidal signal indicating relative movement between the optical sensor and the encoder pattern. In one embodiment, the photo-detector has a diamond shape, a modified-diamond shape, or an hourglass shape. In another embodiment, at least one of the light elements and the dark elements of the optical encoder pattern has a diamond shape, a modified-diamond shape, or an hourglass shape.

Abstract: When a convex lens 13 comes close to 0-th order transmitted light T0 with rotation of an optical scale 11, the 0-th order transmitted light T0 derived from a light beam L emitted from a light source 15 and transmitted through a diffraction grating 12 around is converged and incident on a reference position signal detection sensor 14. At that time, a large output is obtained from the reference position signal detection sensor 14. This signal constitutes a reference position signal. On the other hand, reflective diffracted light beams La, Lb having been reflected by the diffraction grating are detected by a diffraction light detection sensor 16 after interference, so that the speed and the angle etc. of the scale 11 are detected. In this way, the reference position signal and an incremental signal are detected at the same position on the optical scale.

Abstract: In two phases signals (A, B) outputted from a scale or a scale having a discontinuous portion provided in its incidental member to a light receiving portion, a region in which amplitudes of the two phases signals (A, B) are small corresponds to outputs when a reflecting portion lies in the scale in terms of rotation position, and a region in which amplitudes of the two phases signals (A, B) are large corresponds to outputs when a nonreflecting portion lies in the scale in terms of rotation position. An optical encoder for discriminating positions of a reflecting portion and a nonreflecting portion of a scale using a threshold value (L) to detect an absolute position based on a reason that when the signals (A, B) are arithmetically operated by an arithmetic operation processing circuit to obtain a sum of squares of the signals (A, B), change points in the amplitudes of the signals (A, B) are steeply obtained.

Abstract: An angle-measuring system comprising at least one transmitter provided with a number of complementary signal-generating elements disposed in pairs and creating a pattern of signals. The elements create a reference mark irregularly configured at least at one spot. A device for acquiring the signals and an evaluation unit are also part of the angle-measuring system. The device is provided with at least one first sensor and one second sensor.

Abstract: Optical encoders having one or more of a number of disclosed features are disclosed. The features of the optical encoder in accordance with the present invention include a symmetrical (for example, circular) emitter; baffle between the emitter and a detector; double-dome or single-dome encapsulant; multiple detector; and multiple (at least three) data channels.

Abstract: At least one exemplary embodiment is directed to an optical encoder which includes a first diffraction grating having a desired optical effective aperture ratio at an appropriate gap position so as to eliminate and/or reduce high-harmonic components from the light intensity distribution of interference fringes and reduce high-order spatial frequency components overlapped on a displacement signal of the interference fringes formed by the first diffraction grating.

Abstract: An optical encoder is disclosed, in particular, which has a light sensing element with light-sensing cells arranged in a matrix. The light sensing element repeatedly detects the same reflective light beam by different rows of light-sensing cells to increase the precision of feedback control. Furthermore, since the light sensing element synchronously and repeatedly receives the reflective light beam, the reliability of detected signals is increased.

Abstract: An Optical Projecting Encoder (“OPE”) having an emitter module for transmitting emitted optical radiation through a mask to a moving object, and a detector module for receiving reflected optical radiation from the moving object. The reflected optical radiation from the moving object may include a predetermined image cast by the mask and a surface texture image from the moving object. The OPE may include a transmissive layer covering both the emitter module and the detector module, where the transmissive layer covering the emitter module collimates the optical radiation from the emitter module, and the transmissive layer covering the detector module concentrates the optical radiation reflected from the moving object to the detector module. The detector module may include an optical navigation sensor that continuously acquires and compares predetermined images cast by the mask and surface texture images from the moving object.

Abstract: A device for retaining optical components includes a number of open orifices disposed next to one another in an arrangement. A raceway corresponding to the arrangement is provided, the raceway including a number of detents. A ball bearing follows the raceway and cooperates with the detents so that each of the detents is brought, in a respective following direction, into click-stop engagement with the ball bearing so as to hold the orifices in a selected position. Each of the detents has, in the respective following direction, a profile including a combination of an outer and an inner arc-shaped profile. The outer profile has less curvature than the inner profile and surrounds the inner profile.

Abstract: An absolute encoder employs multiple sub-encoders of different resolutions and a linking algorithm for combining the sub-encoder outputs to form an accurate, high-resolution position estimate. The sub-encoders can utilize edge modulation of a main grating track, sloped patterns of successively higher periods, and other types of scale patterns. The sub-encoders can also use a variety of detector types suitable for the patterns being used. In one linking approach, pairs of tracks are linked together successively by applying a phase shift to the coarser track and then combining it with the finer track such that the transitions of the coarse track estimates become aligned with those of the finer track, whereupon the values can be combined to form a linked position estimate. In another approach, beat tracks are calculated from physical tracks of similar period, and the beat tracks are used as the coarser tracks in the linking process.

Abstract: An optical encoder includes a cylindrical reflective scale, a point light source for irradiating the reflective scale, and light-receiving elements for receiving the light beams reflected by the reflective scale. The pitch of the reflective scale is set to an appropriate value such that the pitch of interference fringes formed by light beams that are reflected by the reflective scale is matched to the pitch of the light-receiving elements at a position with a desired gap.

Abstract: In a gantry for an x-ray computed tomography apparatus with a rotor and a stator and a device for measurement of the rotation angle as well as a method for measurement of the rotation angle, a disc is provided with markings that rotate relative to a detection device for detection of the markings. Electrical signals are generated by the detection device, and an evaluation device converts the signals into a measurement signal corresponding to the respective rotation angle. To increase the precision of the measurement, a low-pass filter is connected upstream of the evaluation device.

Abstract: An optical encoder, a system and a method for outputting a signal are provided. The optical encoder and the system have a shaft extending from an interior of a housing. A circuit board having a light emitting element and a light detector is connected to the housing. The light emitting element emits an amount of light within the interior of the housing. A light pipe transmits, deflects and/or directs the amount of light from the light emitting element toward the light detector. A rotor which is connected to the shaft rotates to change the amount of light received by the light detector. The shaft is connected to a sprocket which contacts a spring to produce a sound or vibration which indicates the shaft is rotating, twisting and/or turning. The circuit board outputs a signal via a cable based on the amount of light received by the light detector. The signal corresponds to a position and/or a location of the shaft.

Abstract: An optical encoder assembly and a method for measuring a rotation angle in which optical beams are spread over the circumference of a rotating optical disk by means of optical guides (OG). In the preferred embodiment the rotating optical disk has a pair of concentrically arranged circular patterns with alternating transparent and opaque sections. Each beam is input via optical fibers to one of a pair of concentrically disposed OGs with a cylindrical shape (COGs) respectively and propagated through the optical disk to be reflected by a mirror with two concentrically disposed circular patterns of reflective and non reflective sections, reentering the COG through the optical disk in a reverse direction. The COGs then guide the light beams back to an electronic interface that converts the optical signals into electronic signals producing position information.

Abstract: A position measuring system having a scale that includes an incremental graduation track, which extends in a measuring direction, the incremental graduation track having a periodic arrangement of graduation areas with different optical properties and a reference marking in a reference position, which has an aperiodic arrangement of graduation areas. A scanning unit including a light source and an opto-electronic detector arrangement having a reference pulse signal detection unit for generating a reference pulse signal. A periodic strip pattern results in a detection plane, which is amplitude-modulated in an area of the reference position, wherein the reference pulse signal detection unit includes several reference pulse signal detection elements, which create the reference pulse signal so that a periodic signal portion, as well as low-frequency signal portions are filtered out of the incremental graduation track to a large degree.

Abstract: An optical encoder is comprised of three component parts, which are an emission-side light-pervious resin 6 by which a light emitting chip 1 is sealed, a reception-side light-pervious resin 8 by which a light receiving chip 2 is sealed, and an outer casing 4 to which a lens 3 is integrated and in which the emission-side light-pervious resin 6 and the reception-side light-pervious resin 8 are housed. Thus, the optical encoder can be reduced in parts count, allowing the development cost to be reduced, as compared with the case where the lens 3 for collimating light derived from the light emitting chip 1 and the outer casing 4 are provided as independent component parts.

Abstract: A rotary optical position encoder for detecting angular position includes a light source, a monolithic scale disk including an optical scale pattern, a monolithic reticle substrate including sets of reticle aperture patterns between the light source and the scale disk, detection and conversion circuitry, and digital processing circuitry. The light source, scale disk, reticle substrate, and detection and conversion circuitry form a plurality of optical sub-encoders at angular positions about the rotational axis, each sub-encoder having an optical path extending from the light source to the detection and conversion circuitry via a respective set of reticle aperture patterns and the optical scale pattern. The digital processing circuitry is operative to combine digital position output values of the sub-encoders to generate an encoder position output value.

Abstract: A photoelectric encoder includes a light source of an illumination light beam. The encoder also includes a movable grating which has grating lines and which is displaceable in a direction intersecting the grating lines. An index grating serves as a reference for displacement of the movable grating. A light-receiver receives the illumination light beam via the movable grating and the index grating. A modulator periodically changes a light beam outgoing from the index grating. A displacement detector detects the displacement of the movable grating based on the illumination light beam received by the light-receiver. Accordingly, a signal representing the displacement of a movable body can be accurately generated even when fluctuation of the attitude of the grating occurs.

Abstract: A main scale of an optical displacement measuring apparatus has slits arranged on it at regular intervals, a part of which is a missing slit that does not allow light to pass through used for detecting the original point. An index scale has four sets of windows formed on it. The four windows are arranged with mutual phase differences of ¼ P, where P is the pitch of the arrangement of the slits. When a part of the missing slit overlaps with the index scale, no light reaches to photodiodes from the missing slit and only a partial light flux passes through a window, so that the light quantity decreases. An original point signal associated with the missing slit can be obtained by adding up the outputs of all the photodiodes.