Abstract: A method for determining an optical constant of a material includes: acquiring ellipsometric parameters; obtaining a optical constant of the material corresponding to the ellipsometric parameters by a machine learning model; the machine learning model including a mapping relationship between the ellipsometric parameters and the material optical constant of the material corresponding to the ellipsometric parameters. The method uses the machine learning model to implement an automatic fitting of ellipsometric parameters. In the method, the optical constant of the material is calculated by a machine learning model, which no longer depends on the experiences of the experimenters, thereby reducing requirements for the operator, accelerating the fitting of the data curve when calculating the optical constants of the material and improving the operation efficiency.

Abstract: An image forming apparatus includes first and second light emitting units, a light receiving unit for receiving light of the first light emitting unit when it is reflected, and receiving light of the second light emitting unit when it is not reflected, to output a signal of a predetermined level, and a control unit for starting light emission of the first light emitting unit before a front end of a paper sheet reaches an area, stopping light emission of the first light emitting unit while starting light emission of the second light emitting unit before a rear end of the paper sheet passes the area, and detecting a length of the paper sheet based on time after the output signal becomes a predetermined level during light emission of the first light emitting unit until the output signal becomes the predetermined level during light emission of the second light emitting unit.

Abstract: A printing apparatus includes a media bin and a sensor, directed toward the media bin, having a first emitter and a receiver. The printing apparatus further includes a second emitter to emit photons toward the optical sensor, and a controller. The controller determines presence of a print media on the media bin based on a count of photons received from a source other than the first emitter, including the second emitter.

Abstract: A paper sheet recognition apparatus can generate a subtracted reflective light image without increasing detection time. To that end, the operations of sensors are controlled in a plurality of phases. The phases include a phase (reflected infrared light 1) in which a first light emission unit emits light, a second light emission unit emits no light, and an optical sensor detects reflective light. In another phase, (reflected infrared light 2) the first light emission unit emits no light, the second light emission unit emits light, and the optical sensor detects reflective light. In at least one of these phases, a light emission unit emits light, and an optical sensor detects transmissive light.

Abstract: A method for measuring a position of a target surface provided with portions for position determination thereon, wherein a diffuse reflectance of the target surface is 0.1% or less, and a diffuse reflectance of the portions for position determination is 5% or more, and wherein the target surface is configured such that a tangential plane at any point on the target surface where each of the portions for position determination is installed forms an arbitrary angle between 15 degrees and 75 degrees inclusive with a certain direction, the method including the steps of illuminating the target surface with parallel light in the certain direction; determining positions of border lines of the plural portions for position determination from an image of the target surface; and determining the position of the target surface from the positions of the border lines of the plural portions for position determination.

Abstract: The element according to the present invention has a first plane (201) and a second plane (203) forming a prescribed angle with the first plane. The second plane is provided with at least three portions for position determination (101A 101B, 101C, 101D) arranged on the second plane sufficiently spaced apart from each other, allowing the identification of the second plane. Each portion for position determination is formed in a convex shape with respect to the second plane. A tangential plane (TL) to the surface of each portion for position determination at a point on a border line between the second plane and the surface forms a single plane and tangential planes of the portions for position determination are parallel to one another.

Abstract: A method of inspecting a wire contact includes determining, at a processor, a striation metric of a particular image of the wire contact. The particular image depicts an inspection hole in the wire contact. The method also includes comparing the striation metric to a wire-in-hole detection threshold and determining that a threshold number of visible wire strands are oriented along a particular axis in the inspection hole if the striation metric satisfies the wire-in-hole detection threshold.

Abstract: A camera lens cleaning system includes a camera, a cleaning device, a processing unit, and an executing unit configured to move the color testing disk and the cleaning device. The camera is used to capture a plurality of different color images of a color testing disk located below the camera. The processing unit is used to process every adjacent two different color images to obtain a difference color value; thereby the processing unit compares the different color value with a reference color value to determine whether dirt is located on a camera lens of the camera. When the dirt is located on the camera lens, the executing unit is configured to move the cleaning device to clean the camera lens. The disclosure further offers a camera lens cleaning method.

Abstract: A method for checking the soiling of the windows of a measuring apparatus for checking sheet material, includes having at least two sensor rows oriented transversally to the transport direction of the sheet material. Each of the sensor rows detects the light emanating from the sheet material in a certain spectral channel. For checking the soiling of the window the sensor rows detect the light at several detection times at which no sheet material is present in the capture area of the sensor rows. At least two of the spectral channels are combined with each other and the temporal variation of the intensities of the combined spectral channel is evaluated for the purpose of the soiling check. A small temporal variation of the intensity of the combined spectral channel is employed as an indicator for the presence of a soiling of the window.

Abstract: A method for calibrating alignment of an end effector with respect to a chuck in a plasma processing system is disclosed. The method includes providing a first light beam from the end effector to said chuck, moving the end effector along a predefined calibration path such that the first light beam traverses a surface of the chuck, receiving a set of reflected light signals being generated at least when the surface reflects the first light beam during the moving, and analyzing the set of reflected light signals to identify three or more discontinuities, generated when the first light beam encounters an edge of the chuck. The method also includes determining three or more coordinate data points representing three or more points on the edge of the chuck, and determining a center of the chuck based on the three or more coordinate data points.

Abstract: A system for measuring properties of a thin film coated glass having a light source, a spectrometer, at least one pair of probes, a first optical fiber switch and a second optical fiber switch. The pair of probes includes a first probe located on one side of a glass sheet and a second probe located on the opposite side of the glass sheet, directly across from the first probe. The first and second optical fiber switches are adapted to couple either probe to the light source and/or the spectrometer. Because the design of the system is optically symmetrical, calibration may be performed without the use of a reference material such as a tile or mirror. Each of the first and second probes has a first leg and a second leg that are separated from each other by a distance n so that angled reflections may be detected.

Abstract: A system for measuring properties of a thin film coated glass having a light source, a spectrometer, at least one pair of probes, a first optical fiber switch and a second optical fiber switch. The pair of probes includes a first probe located on one side of a glass sheet and a second probe located on the opposite side of the glass sheet, directly across from the first probe. The first and second optical fiber switches are adapted to couple either probe to the light source and/or the spectrometer. Because the design of the system is optically symmetrical, calibration may be performed without the use of a reference material such as a tile or mirror.

Abstract: A method for producing a photosensitive integrated circuit including producing circuit control transistors, producing, above the control transistors, and between at least one upper electrode and at least one lower electrode, at least one photodiode, by amorphous silicon layers into which photons from incident electromagnetic radiation are absorbed, producing at least one passivation layer, between the lower electrode and the control transistors, and producing, between the control transistors and the external surface of the integrated circuit, a reflective layer capable of reflecting photons not absorbed by the amorphous silicon layers.

Abstract: An apparatus includes: a body including a port into which a medium is insertable; a light source that is provided in the body and illuminates when an image is read for the medium that has been inserted into the port; a guide and output unit that is optically connected to the light source, guides light emitted from the light source, and outputs the guided light into the port; a receiver that detects the output light; and a determiner that determines whether the medium has been inserted into the port based on a result of the detection. The light source also illuminates when the determiner makes the determination. A region in the port through which the light output from the light guide and output unit passes exists from one end to the other end of the port in a width direction being a longitudinal direction of the port.

Abstract: A paper sheet processing apparatus capable of preventing authentication accuracy from degrading even when a state change occurs due to attachment of water or the like. The paper sheet processing apparatus includes: a light receiving unit which receives transmitted and reflected lights from the paper sheet radiated by light emitting parts; a converter which converts the transmitted and reflected lights received by the light receiving part per pixel into data including color information having brightness; a RAM which stores transmitted and reflected light images received by the light receiving unit; an authenticity judgment processing part which determines the authenticity of the paper sheet based on the images stored in the RAM; and a determining part which excludes, based on a comparison result between brightness of the transmitted and reflected images in the predetermined area.

Abstract: A multifunction detector for detecting energy reflected from the surface, the detector comprising: a focal plane array in communication with the optical receiving path; and an optical receiving path; a read-only integrated circuit in communication with the optical receiving path, integrated with a focal plane array; and a processor programmed to operate the focal plane array and read-out integrated circuit in a first mode to process signals in a first frequency band, and in a second mode to process signals in a second, wider frequency band.

Abstract: A running yarn line inspection method inspects yarn lines running in parallel in the same surface. The running yarn line inspection method is provided with a first illumination means and a line sensor for imaging the yarn lines on the side of the first surface of the running surface of the yarn lines and a second illumination means on the side of the second surface, and comprises a data processing means which processes data obtained by the line sensor and a recording means which records data processed by the data processing means with time.

Abstract: Image sequences are accessed, the sequences each taken, from a different perspective, of a portion of a radiation region defined by projected electromagnetic radiation. The image sequences each include a projection image taken during an emitting period in which the projected electromagnetic radiation is emitted, the projection image being of ambient electromagnetic radiation and of an object within the portion being illuminated with the projected electromagnetic radiation, and an ambient image taken during an extinguishing period in which the projected electromagnetic radiation is extinguished, the ambient image being of the ambient electromagnetic radiation. A position of the object using the projection images and the ambient images is determined, an application is controlled based on the determined position.

Abstract: A measurement system for measuring a degree of moisture stratification in a flat sheet product, such as paper, board or other materials. The system uses a combination of a reflection gauge and a transmission gauge to provide output signals indicative of surface moisture of a first side and of moisture in the body of the flat sheet product. The output signals are processed by a controller or computer to provide a measurement of the moisture stratification. An additional reflection gauge and an additional transmission gauge can also be used to provide additional output signals indicative of surface moisture of a second side of the flat sheet product and of moisture in the body. Narrow band radiation is used with modulation to distinguish from ambient radiation as well as radiation incident on the opposite side.

Abstract: A method to sense pH of a fluid and an optical pH sensor. The method includes the steps of supplying at least a portion of an optical source through an input fiber. The optical source is passed through a sensor head having a sapphire window to a fluid. Optical power reflected from the fluid is collected in a plurality of output fibers in the sensor head. The reflected optical power in the output fibers in the sensor head is thereafter converted to an electrical signal which is used to determine the pH of the fluid.

Abstract: To determine authenticity of a solid body simply and precisely, a reference area of a paper sheet which is genuine is optically read from two different directions, and the image is registered as a reference image. A check area of a paper sheet subjected to the authenticity determination, including the reference area and having a size larger than the reference area, is read from two different directions with a scanner, and data on a partial area having the same size as the reference area are extracted from each set of check data collected by the reading. For a set consisting of the reference image and the check image optically read from the same direction, the value of the correlation with the reference image is repetitively calculated by the normalized correlation method while the partial area is shifted within the check area. The maximum correlation value and the normalized score of the maximum correlation value are compared with respective thresholds to determine the authenticity of the paper sheet.

Abstract: A system and method for determining a brightness factor associated with a window shade fabric is disclosed. The brightness factor incorporates the openness factor of the fabric, visible light reflectance of the fabric and visible light transmission of the fabric. The brightness factor helps to determine the optimum window shade fabric for a particular room, building or other location. The brightness factor information may be used to select the correct fabric based on desired interior function, light level, the relative surface brightness, and/or any other desired interior characteristic. The fabric selection may affect the building envelope by, for example, facilitating the optimization of daylighting, reduction of artificial electric lighting needs, and minimization of glare conditions.

Abstract: An optical sensing device for detecting plural optical features of valuable papers is provided that comprises first and second photocoupers 5 and 6 or 9 and 10 positioned in the vicinity of and on the opposite sides of a passageway 13 for guiding the valuable paper 64. Each of first and second photocouplers 5 and 6 or 9 and 10 has a light emitting element 20, 22, 30, 32 for emitting a light, and a light receiving element 21, 23, 31, 33 for selectively receiving the light from the light emitting element 20 so that each light receiving element 21, 23, 31, 33 can receive lights reflected on and penetrating the valuable paper 64 for detection of multiple optical features from the valuable paper 64.

Abstract: An optical sensing device for detecting plural optical features of valuable papers is provided that comprises first and second photocouplers 5 and 6 or 9 and 10 positioned in the vicinity of and on the opposite sides of a passageway 13 for guiding the valuable paper 64. Each of first and second photocouplers 5 and 6 or 9 and 10 has a light emitting element 20, 22, 30, 32 for emitting a light, and a light receiving element 21, 23, 31, 33 for selectively receiving the light from the light emitting element 20 so that each light receiving element 21, 23, 31, 33 can receive lights reflected on and penetrating the valuable paper 64 for detection of multiple optical features from the valuable paper 64.

Abstract: A multifunction detector for detecting energy reflected from the surface, the detector comprising: a focal plane array in communication with the optical receiving path; and an optical receiving path; a read-only integrated circuit in communication with the optical receiving path, integrated with a focal plane array; and a processor programmed to operate the focal plane array and read-out integrated circuit in a first mode to process signals in a first frequency band, and in a second mode to process signals in a second, wider frequency band.

Abstract: A paper sheets feature detector 20, through which a banknote 21 is carried and passed is provided with a carrying-in sensor part 22, a transmissive and reflective line light sensor 23, a magnetic sensor 24, a thickness sensor 27, and a carrying-out sensor part 28. When a watermark part of the banknote 21 is measured by the line light sensor 23, a watermark pattern is detected by a light transmissive sensor, and that pattern is not detected by a light reflective sensor, the banknote 21 is determined to be a true banknote. Watermark braille is similarly processed. When the thread is detected by the light transmissive sensor and the thread is not detected by the light reflective sensor, the banknote 21 is determined to be a true banknote.

Abstract: In an apparatus for processing banknotes or other sheet-like objects, the banknotes are conveyed along a transport path, thereby passing sensor means. A transmission and a reflection image of the banknote are captured by illuminating the banknotes and measuring the transmittive and reflective light intensity of light with a high resolution. Based on these images, a validation of the banknotes is carried out. After the validation, a double feed detection is performed by evaluating the transmission and the reflection intensities for a predefined set of test spots with a two-dimensional evaluation. If it is decided on double feed, the banknotes are rejected. Otherwise the banknotes are accepted and further processed. Because of the additional dimension in the evaluation compared with known double detection methods, the invention enables a more robust double note detection also in cases with different degrees of soiling of the banknotes.

Abstract: A defect inspection apparatus includes an illumination optical system which sets a transmission illumination region and a reflection illumination region on an inspection target surface of a mask, first and second imaging units having first and second visual fields which are set on the inspection target surface, an imaging optical system that provides images, which are present on the first and second visual fields, on the first and second imaging units, a defect detection unit which detects a defect of the mask on the basis of the images provided on the first and second imaging units, and a control unit which controls a positional relationship between setting positions of the transmission illumination region and the reflection illumination region and setting positions of the first and second visual fields.

Abstract: When using a CCD sensor as a photo-detector in a device for inspecting foreign matters and defects, it has a problem of causing electric noise while converting the signal charge, produced inside by photoelectric conversion, into voltage and reading it. Therefore, the weak detected signal obtained by detecting reflected and scattered light from small foreign matters and defects is buried in the electric noise, which has been an obstacle in detecting small foreign matters and defects. In order to solve the above problem, according to the present invention, an electron multiplying CCD sensor is used as a photo-detector. The electron multiplying CCD sensor is capable of enlarging signals brought about by inputted light relatively to the electric noise by multiplying the electrons produced through photoelectric conversion and reading them. Accordingly, compared to a conventional CCD sensor, it can detect weaker light and, therefore, smaller foreign matters and defects.

Abstract: A multi-sheet feed detection system comprises a photosensor configured to receive light emitted in a non-visible spectrum by a transmitter through at least one sheet, and a detection module configured to detect a multi-sheet feed condition based on an amount of non-visible light received by the photosensor.

Abstract: A tube-like reflector insert for a sensor is located in a rigid, light-absorbing sleeve that is closed on one side, and forms a two-part reflector body with the sleeve. A nut is glued onto the open side of the sleeve to enclose the reflector insert. The intravasal part of the sensor is guided in a protective tube having connector threads glued on on both sides. This protective tube is screwed onto the Y connector piece and the reflector sleeve with the nuts. The tip of the sensor is inserted with slight play into the sensor cavity of the reflector insert. The play ensures that sterilization gas can reach all of the intravasal surfaces. The reflector is attached to the sensor via a screw connection outside of the intravasal region, which ensures that the intravasal sensor part is not exposed to clamping stress. Free access for sterilization gas is possible at all intravasal surfaces of the sensor.

Abstract: A Fabry-Perot resonator apparatus and method for observing low reflectivity surfaces provides functional improvements for optical inspection and measurement systems, optical storage and retrieval systems as well as other optical systems when the a surface of interest in the resonator path has a lower than ideal reflectivity. The Fabry-Perot resonator is designed with an angle of incidence on the surface of interest deviating from normal incidence, effectively raising the reflectivity. Resonance is supported either by one or more reflectors oriented at angles with respect to the surface of interest, or by a focusing system that alters the directive angle of optical path(s) within the resonator such that the angle of incidence at an intersection of the optical path with the surface of interest is an angle other than normal. A normal incidence is maintained at the reflector(s), so that resonance is supported between the surface of interest and the reflector(s).

Abstract: A paper sheets feature detector 20, through which a banknote 21 is carried and passed is provided with a carrying-in sensor part 22, a transmissive and reflective line light sensor 23, a magnetic sensor 24, a thickness sensor 27, and a carrying-out sensor part 28. When a watermark part of the banknote 21 is measured by the line light sensor 23, a watermark pattern is detected by a light transmissive sensor, and that pattern is not detected by a light reflective sensor, the banknote 21 is determined to be a true banknote. Watermark braille is similarly processed. When the thread is detected by the light transmissive sensor and the thread is not detected by the light reflective sensor, the banknote 21 is determined to be a true banknote.

Abstract: A system and a method for detecting defects in a light-management film are provided. The system includes a first light source configured to emit light onto a first side of the film in a first predetermined region of the film. The system further includes a second light source configured to emit light onto a second side of the film in the first predetermined region of the film. The system further includes a first camera configured to receive a first portion of light reflected from the first predetermined region of film from the first light source and a second portion of the light propagating through the film from the second light source. Finally, the system includes a signal-processing device operably coupled to the first camera configured to detect a defect in the first predetermined region of the film based on at least one of the first and second portions of light.

Abstract: A method of one embodiment of the invention is disclosed that detects approachment of an edge of a media sheet by detecting light reflected by the media sheet. Upon detecting the approachment of the edge of the media sheet, the method detects the location of the edge by detecting light transmitted through the media sheet.

Abstract: A value of infrared energy reflected from a metallic substrate with a polished surface is determined. The value of the infrared energy reflected, or conversely absorbed, is correlated to a quality of polish. According to an aspect of the invention, one embodiment of the invention utilizes an infrared spectrometer to determine the infrared absorbance of a polished metallic substrate. An infrared beam is reflected off the metallic substrate. The infrared energy of the reflected beam is compared with a pre-determined value of infrared energy reflected off a reference polish surface.

Abstract: An apparatus and method for web inspection utilize simultaneous capturing of reflected and transmitted light images for real-time merging of same. The reflected light and transmitted light image capturing systems are registered with each other in terms of the down-web and cross-web field being imaged. To allow for the simultaneous acquisition of reflected and transmitted light images, the imaged portion of the web is an unsupported span, and the web is tensioned to prevent sagging. The reflected light and transmitted light image capturing systems each include multiple cameras registered with each other in terms of down-web and cross-web imaging field, and the cameras for the transmitted light image capturing are aligned directly with the light source, which outputs light that is incident on the web at an angle.

Abstract: A system of classifying incoming media entering an inkjet printing mechanism identifies transparency media without requiring any special manufacturer markings. The media is first optically scanned using a blue-violet light at an initial intensity to obtain both diffuse and specular reflectance data. If useable, the data is compared with known values to classify the media so an optimum print mode tailored for the particular media is used. The early transparency detection system avoids time-consuming further steps trying to classify the media as photo media, plain paper, and the like, and facilitates fast printing of transparencies, which can be critical in the business environment when making last minute changes for a presentation. A printing mechanism constructed to implement this method is also provided.

Abstract: A sensing mechanism for an image-forming device of one embodiment of the invention is disclosed that includes a first light source, a second light source, a detector, and a controller. The first light source is positioned incident to a first side of media, whereas the second light source is positioned incident to a second side of media opposite of the first side of the media. The detector is positioned incident to the second side of the media to detect first light transmitted through the media as output by the first light source, and to detect second light reflected off the media as output by the second light source. The controller is to detect at least one characteristic of the media based on a ratio of the first light to the second light.

Abstract: A method and an apparatus for automatic inspection of flatly positioned pieces of cloth with a view to detecting impurities or other irregularities in pieces of cloth. The pieces of cloth are transported past a camera (10) that is, in cooperation with a digital storage unit, configured for producing a digital image of each piece of cloth or portions of each piece of cloth; and wherein the apparatus comprises one or more light emitters (11) with a view to illuminating at least that part of a piece of cloth that is within the field of vision of the camera (10). Each piece of cloth is conveyed from a receiver conveyor (12) to a delivery conveyor (13), the field of vision of the camera (1) being configured to have at least an open area (14) between these two conveyors (12, 13), whereby the digital image is recorded during the passage of a piece of cloth from the receiver conveyor (12) to the delivery conveyor (13).

Abstract: In a process of manufacturing a semiconductor device, after a gate oxide film is formed, the thickness of the gate oxide film is measured by measuring an exposure period defined from a time at which the oxide film is formed to a time at which the thickness of the oxide film is measured. In addition, if necessary, the measurement of the oxide film is corrected to determine the real thickness based on the exposure period. Accordingly, the thickness of the gate oxide film can be measured accurately.

Abstract: A light spectrum detecting apparatus according to the present invention comprises a photodetector (13) and a light transmitting plate (13b) covering a light receiving surface (13a) of the photodetector (13), and in the apparatus, a front surface S of the light transmitting plate 13b is inclined and, among incidents lights, any light once reflected by a back surface T of the light transmitting plate (13b) travels thereafter, with being totally reflected by the front surface S and the back surface T of the light transmitting plate (13b), to a side surface 13d of the light transmitting plate (13b). Any stray light can be prevented from entering the photodetector (13).

Abstract: A reading arrangement includes at least one linear detector arrangement which is arranged in parallel relationship above a reading plane and behind an optical imaging element and is oriented on to a reading region of the reading plane, lighting devices and an evaluation unit and serves for machine reading of an information strip with optically encoded information. The light which is scattered or diffracted out of the reading region in which the information strip to be read off by machine is disposed into the optical imaging element is so projected on to the photosensitive faces of the detector arrangement that an image of the reading region is formed. The detector arrangement produces two detector signals and from a comparison of the detector signals, the read information is determined and its authenticity verified.

Abstract: A method and system for performing swept-wavelength measurements within an optical system provides improved operation in resonator-enhanced optical measurement and data storage and retrieval systems. The system includes an illumination subsystem having a swept-wavelength mode, a detection subsystem, an interferometer or an optical resonator interposed in an optical path between the illumination subsystem and the detection subsystem and a time domain analysis subsystem. Multiple resonance points of the optical resonator are detected by the time-domain subsystem when the illumination subsystem is in the swept-wavelength mode in order to determine resonator or interferometer characteristic changes. The resulting information can be used directly as a measurement output, or cavity length information may also be used to adjust the operating wavelength of a constant wavelength mode of the illumination subsystem.

Abstract: The characteristics of a product such as fruit are determined by analysing light reflected from or transmitted through the product. A tracking means which in one embodiment has an oscillating mirror and in another a light switching means enables a product to be tracked during its movement. Radiation other than that in the visible spectrum may be used.

Abstract: Process and apparatus for determining properties of a traveling material web. The process includes simultaneously illuminating a plurality of measuring points on the material web with electromagnetic radiation, and imaging, through at least one optical device, the plurality of measuring points on one detection surface of at least one detector. The device includes at least one radiation source for illuminating a plurality of measuring points on the material web, at least one detector having a detection surface, and at least one optical device for imaging of the measuring points on the detection surface of the at least one detector.

Abstract: A system of classifying incoming media entering an inkjet printing mechanism identifies transparency media without requiring any special manufacturer markings. The media is first optically scanned using a blue-violet light at an initial intensity to obtain both diffuse and specular reflectance data. If useable, the data is compared with known values to classify the media so an optimum print mode tailored for the particular media is used. The early transparency detection system avoids time-consuming further steps trying to classify the media as photo media, plain paper, and the like, and facilitates fast printing of transparencies, which can be critical in the business environment when making last minute changes for a presentation. A printing mechanism constructed to implement this method is also provided.

Abstract: An optical measurement and inspection method and apparatus having enhanced path length detection uses a Fabry-Perot cavity to increase the phase detection sensitivity for light reflected from optical structures within a device under inspection. A partially reflective surface is inserted between an illumination subsystem and the device under inspection and the position of the partially reflective surface may be adjusted by a positioner to create the Fabry-Perot cavity between one or more surfaces within the device under inspection. The detection of phase changes is improved, providing improved sensitivity to optical path differences produced by structures within the device under inspection.

Abstract: A method of validating selected properties of media includes: providing a sensor having a monochromatic light source and a light detector, with the detector being positioned to receive only diffusely reflected light from the source; locating the media in the path of the sensor; activating the light source, and detecting light diffusely reflected from the media to provide an output from the detector containing data relating to the response of the media to the light source; moving the media with respect to the sensor so as to gather sample data from different areas of the media; processing the sample data to determine a selected characteristic of the media; and comparing the sample data against a reference database of data obtained from genuine media.

Abstract: An optical sensor includes a light-emitting element and first to third light-receiving elements. The light-emitting element is arranged on a first side of a transfer path along which a recording sheet is moved. The first light-receiving element is arranged on a second side of the transfer path which is opposite to the first side. The second and the third light-receiving elements are arranged on the first side of the transfer path in the vicinity of the light-emitting element.