Abstract: A detector array for use in a laser imaging apparatus, comprises a plurality of housings disposed in an arc around an opening in which an object to be scanned is disposed, each housing including an open front end, a rear end and a longitudinal axis; and a detector disposed within each housing at a distance from the front end, thereby to restrict the field of view of each detector. The housings are adapted to be orbited around the object about an orbit axis. Each detector is adapted to simultaneously detect light exiting from the object within the respective field of view of each detector. A method for collecting light exiting from a object being scanned with a light source is also disclosed.

Abstract: An apparatus for the detection of surface flaws in material having a surface which is partially reflective includes at least one light source arranged to direct incident light on a surface of an at least partially reflective material, and a light detector disposed above the surface of the material. The light detector and the at least one light source are arranged relative to each other such that, in the absence of a surface flaw in the material, substantially no light from the at least one light source is detected by the light detector and, in the presence of a surface flaw in the material, light from the at least one light source is reflected off of the flaw and into the detector.

Abstract: An image sensor package cover with an opaque epoxy silk-screened into it. This epoxy is patterned to the appropriate size, for a particular sensor, to form an integral light shield on the cover, while simultaneously covering to the package. This masks the internal light reflections as well as the prior art methods of using a separate light shield, but eliminates a separate component and the costly labor required to assemble such a product. Such a configuration can be applied to a linear or area type image sensor.

Abstract: Many applications of radiant energy transducer systems call for specific performance characteristics over desired fields of view or footprints on identified surfaces. Constructive occlusion utilizes a mask sized and positioned to occlude an active optical area, such as an aperture of a diffusely reflective cavity, so as to provide a tailored performance characteristic. Use of principles of constructive occlusion alone or in combination with several other techniques enable tailoring of the illumination distribution or the sensitivity profile of a radiant energy transducer system to meet the demands of specific applications. One mechanism used to further tailor performance involves a non-diffuse reflective shoulder along a peripheral section of the mask and cavity type system. Another technique involves using a retro-reflective surface, for example along a portion of the periphery of the system, to limit the angular field of view and to redirect light back into the system for emission within the desired field.

Abstract: A stray light baffle for reducing an amount of stray light incident on a detector may comprise a main body portion and a mounting pad portion. The mounting pad portion is affixed to a mounting surface with a light curable adhesive. The stray light baffle substantially blocks stray light and substantially transmits curing light. The mounting surface is located adjacent the detector so that the main body portion of the stray light baffle is interposed between the detector and a source of stray light when the stray light baffle is mounted to the mounting surface.

Abstract: An optical reader is suitable for reading 2-dimensional indicia. The optical reading device, that may include a bar code reader, comprises a guide whose length along the optical reader optical axis is such that when that guide contacts the part or equipment surrounding the indicia to be read, that indicia is within the optical reader depth of field. The reader comprises a housing having therein a source of illumination and optics for producing a diverging beam for illuminating indica. A spacing element transparent guide is removably attached to the housing, and does not block indicia. The line of contact of the guide with the data carrier is substantially fully visible to the operator, who can thus confirm that the guide is in proper operating position relative to the indica prior to initiating a reading operation. A reading operation can be initiated by pressing on the guide to actuate a switch, or on a manual trigger.

Abstract: In an optical rotary encoder, a stationary plate having a zone plate and a rotary slit plate having slits are interposed between a light source and a light receiving element. A suitable radius of the innermost circle of the zone plate is selected so that the zone platess provide a sufficient convergence of light for reduction of silt interval (hence for improvement of the detection precision) with a distance between the stationary plate and the rotary slit plate maintained at a value permitting the fabrication of the encoder.

Abstract: A radiant energy transducer system includes a base. The base has a diffusely reflective surface and an optical area defining a horizon district with respect to the transducer system. A mask occludes a portion of the optical area so as to present a substantially constant portion of the optical area over a range of angles above the horizon district. An electromagnetic transducer converts between radiation associated with the optical area and corresponding signals. Examples of the transducing systems provide emission of radiant energy with a tailored intensity distribution over an area illuminated by the system. Other examples of the transducing systems detect radiant energy, and the position of the mask relative to the optical area of the detector system serves to tailor the sensitivity of the detector over a field of view. The emitters and detectors can be used together, for example in a system for tracking the position of an object.

Abstract: An optical reader is suitable for reading 2-dimensional indicia. The optical reading device, that may include a bar code reader, comprises a lens assembly and a guide detachably mounted on a front portion of the housing for establishing a distance between the lens assembly and an equipment target that is displaced a predetermined distance from a mark target wherein the optical reader further comprises an attaching member for supporting the lens assembly on the guide to form a detachable lens-guide assembly.

Abstract: An illumination system is provided having one or more light sources, opaque baffles, and mirrors for illuminating indicia on a substrate, such as a semiconductor wafer, for viewing by a camera aligned parallel with or at an angle to the substrate. The light sources include light emitting diodes (LEDs) for illuminating soft marks and broad spectrum incandescent lamps for illuminating hard marks. Dark field and light field illuminators are provided for enhanced reading of light indicia on a dark background and dark indicia on a light background, respectively. A light control unit allows for manual or automated control of light source selection and light intensity. Opposing mirrors extending along the optical paths of the light sources, reflect light emitted from the light sources into the camera field of view, thereby increasing the illumination efficiency and permitting the use of fewer light sources.

Abstract: A line-focus system with a bulb in a bulb enclosure assembly, where the bulb has a lamp label attached to it in such a manner as to create an occluding aperture for directing light from the bulb toward the scan line in the line-focus system. The lamp label is shaped in such a manner that the light intensity across the photosensor line array in the line-focus system is relatively uniform. The lamp label is furthermore of an opaque, non-reflecting nature so as to prevent any stray light from being reflected into the line-focus system.

Abstract: A short focal length image sensor is formed with an array of photosensor sites and a lenslet array. The lenslet array is comprised of a number of abutting lenslets corresponding in number to the number of photosensor sites. Each lenslet has its optical axis decentered as a function of its radial position in the lenslet array so that each lenslet views a different segment of a total field of view. A field limiting baffle, comprised of one or more separated aperture plates, is included with the center of the apertures in each aperture plate being positioned to lie along the optical axis of a respective lenslet.

Abstract: A system for preventing the escape of electromagnetic emissions includes a metallic electromagnetic shield. The electromagnetic shield is placed substantially around an electronic subsystem. The metallic electromagnetic shield has an aperture opening to allow light reflected from an image to be incident upon a photosensor of the electronic subsystem. An aperture electromagnetic shield is placed over the aperture opening to allow light to pass therethrough and to reduce or eliminate electromagnetic emissions from escaping through the aperture opening.

Abstract: A device is disclosed for determining the position of a body to be positioned with respect to a reference body. The body to be positioned carries a graduation with optical detectors. The coordinates of a projection center are trigonometrically calculated from the projection angles formed between the projection center and at least three light marks projected onto the graduation, as well as from the distance between the light marks. The projection center is formed by the common intersection point between the optical axes or by the common intersection line between the optical planes of at least three diverging and/or converging projectors arranged on the reference body and which emit light beams or light planes. The light marks projected onto the graduation are detected by the optical detectors.

Abstract: A light sensor comprises two light sensitive areas that are shaped to physically compensate for the decrease in light intensity resulting from movement of a movable object in which an aperture is formed. Movement of the aperture causes the light passing through the aperture to have a decreased circumscribed angle that results in a decrease of light intensity impinging on a light sensitive component. In order to avoid the nonlinearity that can result from the decrease in light intensity as a function of the physical position of a movable object being sensed, the light sensitive areas are tapered by selecting the width of the light sensitive area as a function of the distance from a reference line. The light sensitive areas are tapered by arranging the edges of the areas so that the minimum width of each of two light sensitive areas are abutting each other at the reference line and the edges of both light sensitive areas are tapered outward away from each other at positions farther from the reference line.

Abstract: A louver is mounted adjacent a sensor in a housing of a laser scanning head of a system for electro-optically reading bar code symbols. The louver includes a plurality of mutually parallel, permanently-open slots. The slats are inclined to allow more light from far-out symbols to reach the sensor as compared to close-in symbols.

Abstract: In a system for electro-optically reading coded indicia, such as bar code symbols, a light sensor in a scanning head generates higher amplitude electrical signals for symbols closer to the head, and lower amplitude electrical signals for symbols further from the head. To decrease this amplitude variation, and thereby increase the depth of the field of the system, various optical elements such as a lens, a louver, a filter and a shade, are proposed.

Abstract: Position detecting system for a body which changes position, comprising a series of markings made at a mutual distance from one another in a scanner unit, which is movable with respect to the series of markings, for scanning the markings, the series of markings or the scanner unit being connected to the body, the markings being made in various groups of a predetermined number of adjacent markings in the series, the markings per group always being made in a sequence such that the sequence belongs to only one group.

Abstract: The assessment of clearance conditions in an operating turbine structure has provide difficult to achieve. The invention provides apparatus which enables the clearance between seal fins on rotating blades and adjacent fixed structure, to be observed during rotation, and comprises refracting prisms (30, 32) on the fixed structure arranged so as to straddle sealing fin (14) on the blades. The stage of blades on their associated disc are moved towards the fixed structure and light which is refracted through the prisms is obscured by the fins. In one embodiment, the ratio of obscured to unobscured light is utilised to generate electrical signals, which are then manipulated so as to indicate the magnitude of the clearance.

Abstract: An apparatus for illumination and imaging of a surface includes an apparatus for illuminating the surface, an apparatus for obtaining an image of the illuminated surface and providing an output signal representative of the obtained image, and an apparatus for limiting the exposure time of the image-obtaining apparatus to a selected fast exposure time less than the video frame rate of the image-obtaining apparatus. The image-obtaining apparatus may be a CCD-based camera. The CCD-based camera and the illumination apparatus may be mounted in a shroud having an opaque side wall. A first polarizing film may be provided intermediate the illumination apparatus and the surface, and a second polarizing film, having a polarization orientation orthogonal to that of the first polarizing film, may be provided intermediate the surface and the image-obtaining apparatus.

Abstract: A thin-film semiconductor pinhole component with monolithically integrated position-sensing photodetectors is herein referred to as a Position Sensitive Pinhole (PSP). Another embodiment is also discussed where a PSP is integrated onto a platform with controllable motion and is herein referred to as a Movable Position Sensitive Pinhole (MPSP). A third embodiment describes the MPSP with capacitive, electrostatic actuation incorporated into the device to achieve controlled motion, herein referred to as a Capacitively Actuated Movable Position Sensitive Pinhole (CAMPSP). Each of those embodiments of the present invention are discussed, as are their method of manufacture and use in a laser environment as a spatial filter.

Abstract: An optical memory stores data in an optical data layer capable of selecting altering light such as by changeable transmissivity. Data is organized into a plurality of regions or patches (called pages) in which each page contains a field of data spots storing binary data as the presence or absence of a hole. The data is illuminated by controllable light sources and an array of single element diffractive imaging lenslets, one for each data page, projects the image onto a common array of light sensors. By selective illumination of each data page, one of the single element lenslets images the selected data page of holes onto the light sensors. By selecting a hole size and using a certain range of restricted acceptance angle grooves on the diffractive elements, the data image is optimized for a single diffractive element lens.

Abstract: An optical position detecting unit comprising: a light-receiving device including a pixel array to form a light-receiving region and for outputting signals with respect to light detected by respective pixels in the pixel array; a pattern member disposed in the front of the light-receiving region of the light-receiving device and having a pattern having a characteristic that an image of the pattern projected onto the light-receiving region by an incident light beam determines the direction of incidence of the light beam univocally; and a signal processing device for extracting information with respect to the direction of incidence of the light beam on the basis of the signals outputted from the respective pixels in the pixel array. The pattern preferably has M-sequence characteristic.

Abstract: In an optical position sensor capable of detecting a direction of incidence of light and intensity, this invention contemplates to make the sensor compact by reducing the number of pixels constituting light reception sensors and reducing the light reception area. To accomplish this object, a detection element portion 10 comprises a glass substrate 22, a light shading film 24 formed on a surface of the glass substrate 22 and having mutually criss-crossing slits 24a, 24b and a light reception portion 26 fixed to the back of the glass substrate 22. Unidimensional photo-diode arrays 26X, 26Y for receiving the slit beams passing through the slits 24a, 24b respectively, and a signal processing circuit 28 for scanning the photo-diode arrays 26X, 26Y and taking out light reception signals are disposed in the light reception portion 26.

Abstract: A color image reading apparatus comprises a plurality of line sensors which are a plurality of one-dimensional sensor arrays disposed on a single substrate, a projection optical system for projecting an image of a subject on the sensors, a blazed diffraction grating disposed in an optical path between the projection optical system and the sensors to separate light from the subject into a plurality of color lights, and a wavelength selection device disposed in an optical path between the subject and the sensors to permit only a beam of light within a specific wavelength range to pass therethrough.

Abstract: An apparatus includes a light source for emitting a light beam, a light beam expander for expanding the light beam in a predetermined direction, and radiating the expanded light beam onto an object to be inspected, a scanning device for moving the object to be inspected relative to the light beam to be radiated onto the object to be inspected, and a photodetector for photoelectrically converting scattered light generated from a defect (including foreign matter) on the object to be inspected, and inspects the defect on the basis of a photoelectric conversion signal obtained from the photodetector. A light-shielding plate having a plurality of edges for limiting the light beam expanded by the light beam expander at the two end portions, in the expansion direction, of the light beam is arranged, and at least one of the plurality of edges is formed to be transverse to the relative scanning direction (Y direction).

Abstract: An illumination system is provided having one or more light sources, opaque baffles, and mirrors for illuminating indicia on a substrate, such as a semiconductor wafer, for viewing by a camera aligned parallel with or at an angle to the substrate. The light sources include light emitting diodes (LEDs) for illuminating soft marks and broad spectrum incandescent lamps for illuminating hard marks. Dark field and light field illuminators are provided for enhanced reading of light indicia on a dark background and dark indicia on a light background, respectively. A light control unit allows for manual or automated control of light source selection and light intensity.

Abstract: An optical mouse comprises an illumination system for converging light emitted from a light emitting element to a light pattern of a mouse pad, an image forming system for forming an image of the light pattern on the side of a light receiving element and an aspherical lens having a positive refractive index and formed with an aspherical surface in at least one surface thereof. The aspherical surface is used for the illumination system and/or the image forming system. In a preferred form, the aspherical lens is a single lens made of a synthetic resin for constituting the image forming system and satisfying the following optical conditions:2<.vertline..beta..vertline.<150.2<r.sub.1 .multidot.(n-1)/f-3<K.sub.2 <00.012<NA<0.18where .beta.=a magnificationr.sub.1 : a radius of curvature of a surface of the lens on the mouse pad side;n: the refractive index of lens material in wave length: 950 nm);f: a focal distanceK.sub.2 : a cone coefficient; andNA: the number of apertures.

Abstract: A video clock signal generator comprises: means for supplying a light beam; a mask having opposite ends spaced by a predetermined distance; a vibration scanner for reflecting the light beam and forming a light spot vibrating on the mask beyond the opposite ends thereof; a detector for generating an output signal representing optical information from the mask; a counter for counting a time required for the light spot to cross the opposite ends of the mask based on the output signal of the detector; and a control unit for controlling an amplitude of the scanner mirror in accordance with the time counted by the counter.

Abstract: A pollution/smoke detector apparatus is disclosed having a sample chamber of two part molded plastic construction having a pair of matching interlocking pairs including a series of interfitting baffles forming a series of irises spaced along the chamber, the apparatus including at one end a light receptor and a light absorber at the other end, and an air sample area between the subject of a flash light emitted from a light source module having a novel reflector element. The overall construction is easily assembled and disassembled for maintenance and yet provides effective and efficient operation.

Abstract: A measurement system for fiber sensors includes a broadband light source 11 providing continuous light which is launched into a fiber 20 having a plurality (or string) of Bragg grating sensors 24, 28, 34. Each sensor has a predetermined central reflection wavelength which shifts as a function of applied strain. Reflected light 40 from the sensors 24, 28, 34 are fed to a plurality of optical bandbass filters 50, 64, 78, each having a monotonic region in a passband corresponding to one of the sensors. Each monotonic region transmits the reflected wavelength from a corresponding sensor. Light 52, 66, 80 is passed from the filters 50, 64, 78 to optical detectors 54, 68, 82 each providing an electrical signal having a magnitude related to transmission of the filter at the reflection wavelength of the sensor. Optional demodulators 58, 72, 86 are connected to each of the detectors 54, 68, 82 if the light source 10 is modulated.

Abstract: A method and apparatus are disclosed which allow for the detection of an object (14) by the generation of a radiated beam (18) and a subsequent reflection by the object (14) of a portion (20) thereof. The detection of particulate object material (16) due to a reflection of a portion (22) of the generated beam (18) is minimized.

Abstract: An image reading apparatus is provided with a scanning optical system movable to scan an original, the scanning optical system having a slit for passing therethrough part of light from the original, a sensor for reading the light passed through the slit, and detecting means for detecting the relative positional relationship between the slit and the sensor. The detection by the detecting means is effected at a plurality of detecting positions in the direction of movement of the scanning optical system.

Abstract: A quadrant detector arrangement (10) includes a quadrant detector (12) having a photosensitive surface (28) and a plurality of light channels (14) extending therethrough. Light from a light source (16) is collimated by a collimating optical element (18) and projected through the light channels (14) toward a workpiece (36) such that light reflected from the workpiece (36) impinges upon the photosensitive surface (28).

Abstract: The present invention refer to an optical device and data collecting system, more specifically to a system for collecting and analyzing the response of optical sensors, which use may be extended to a large number of devices and equipments with the purpose of analyzing objects in accordance with light reflected or generated thereby. The invention distinguishes from the prior art by having an extremely simple configuration which allows for the determination of specific features such as size, shape, color and speed among others, thus replacing conventional systems which, besides being expensive and complex, do not provide for a large assortment of information and are susceptible to errors and changes in view of environmental conditions.

Abstract: A fiber optic sensor includes a generally cylindrical housing including a fiber optic transmitter in one end connected to a source of light, a sensor within the housing attached to the cylindrical wall of the housing exposed to the transmitted light and responsive to a sensed condition such as acoustic pressure waves to modulate the light, and a fiber optic receiver for receiving the modulated light and supplying it to an external circuit. The sensor may be a thin film fastened to the wall or it may include a diffraction pattern on a reflective inside surface of the wall which will produce a modulated light output with movement of the wall. The thin film may be fastened to the wall directly or suspended by means of Euler struts. The thin film may include a reflective spot and/or a moire pattern for modulating the light.

Abstract: An improved method of collecting quasi-elastic light scattering (also known as QELS) data and time-average intensity simultaneously is disclosed, as is a novel apparatus therefor. The apparatus utilizes a novel optical element having a pair of diametrically aligned slits on a masking disc that eliminates the need of index matching fluids that are currently required to eliminate flare from the sample cell walls at the cell-sample and the cell-air interfaces. The novel optical element allows improved angular resolution and on-axis resolution for the fluctuation data obtained.

Abstract: In an image sensor, a light receptor has a shield film formed substantially centrally in a light receiving area on each of a plurality of light receiving devices, except those disposed at opposite ends of each sensor IC, for adjusting the quantity of light received by each light emitting device. The result is that fluctuation of sensitivity and resolution failure, which might occur during the production of sensor ICs to be used as the light receptor, can be eliminated.

Abstract: A high resolution optical microscope consists of an irradiation spot beam-forming mask which is disposed in a dark or a bright field, whereby a diameter of each of a plurality of irradiation spot beams onto an object to be measured is made smaller than a size of the object, beyond Rayleigh's resolution limit. In the irradiation spot beam-forming mask, a phase array is regularly disposed in a two-dimensional direction so that neighboring portions of each of the irradiation spot beams are optically phase-shifted from one another at 180.degree.. Thus, a wide observation surface and a prompt measurement can be performed with a high resolution of 0.1 .mu.m or less, far beyond Rayleigh's resolution limit.

Abstract: Double banks of LED's, opaque baffles, and a camera having a field of view are disclosed for reading laser-etched character strings and other indicia on semiconductor wafers and other substrates. The LED's of the banks may be integrally or separably lensed, and masks may be provided proximate the banks and in the nearfield of the LED's.

Abstract: A symbol/character discrimination apparatus having a dark-field light source for applying light beams at a predetermined angle of incidence to the surface of a sample on which symbols and/or characters are formed in an indentation pattern, a CCD camera for detecting reflected light beams from the sample surface, and a condensing lens for illumination, diaphragm, and objective optical lens for detection, arranged between the CCD camera and the sample and having a common optical axis. The condensing lens is located between the light source and the sample to condense the light beams from the light source on the surface of the sample and guides the reflected light beams from the sample to the diaphragm. The diaphragm intercepts regularly reflected light beams among the reflected light beams and guides some of the irregularly reflected light beams to the objective optical lens for detection. The objective optical lens guides some of the irregularly reflected light beams to the CCD camera.

Abstract: A device for detecting the inclination of a surface to be examined is disclosed. The device includes an optical arrangement for directing a radiation beam to the surface to be examined, an arrangement for receiving a reflected beam from the surface to be examined and for outputting a signal corresponding to the inclination of the surface to be examined, and a device for changing the size of the beam on the surface to be examined or the size of the beam at a position which is substantially optically conjugate with the surface to be examined.

Abstract: The linearity of a photoresistive device at varying levels of radiant signal is improved by masking the sensitive area of the photoresistive device so that only a portion of the sensitive area is illuminated. The masking prevents exposure of the entire surface area of the cell, which increases the dynamic range, allowing a more linear, small signal sensitivity over wide variations in brightness.

Abstract: A photodetector, for use as a scanning light beam detector in an optical scanner, has a light-detecting element having a light-detecting surface for detecting a scanning light beam. The photodetector has a slit film which has a light-transmissive section for allowing light to be applied to the light-detecting surface and a light-blocking section for blocking light from the light-detecting surface. The slit film is disposed directly on the light-detecting surface. The slit film is evaporated or printed directly on the light-detecting surface. Therefore, the scanning light beam is applied to a desired light-incident area of the light-detecting surface which is positioned and dimensioned with high accuracy. The slit film needs no complex procedure for fine positional adjustment as it is fixedly positioned with respect to the light-detecting element.

Abstract: The solid-state imaging device is applicable to a high sensitivity color camera although its structure is as simple as that of a monochromatic camera, and comprises a semiconductor chip in which a large number of pixels are arranged in a matrix form on one surface of a semiconductor substrate, and an optical grating body for separating an incident light into rays of light to allow them to be incident to the pixel trains in one direction on the chip. The optical grating body includes optical gratings arranged at a pitch corresponding to two or three pixels of a pixel train in a direction perpendicular to the above-mentioned one direction, having a fixed inclination relative to the substrate surface, and juxtaposed provided in the above-mentioned one direction, and a supporting surface for supporting the gratings so that they have the above-mentioned fixed inclination.

Abstract: A process and a device for measuring, through a holographic technique, the deviation of the light rays of a laser beam by more or less transparent objects. The angular deviations (a) of light rays that have passed through the object are measured by an angular measuring instrument (2) located behind an optical system traversed by the light emanating from the object or a hologram formed from the object. The optical system comprises for example one or several lenses (l1, l2), the holographic images forming in the object focal plane of the system, and a diaphragm (D3) located in its image focal plane. The measuring can also be carried out, for example, by turning over the obtained hologram of the transparent object and examining it through a diaphragm. The present invention has application, for example, in the study of flames, of liquid or gaseous flows with strong density variations, of turbulent gaseous mixtures in the combustion chambers of engines, etc.

Abstract: A landslide detecting apparatus which is laid under the ground include: a light source; a lens device for converting a beam of light from the light source into a parallel pencil of rays; a condensing lens device; a light detecting device; and a shading mechanism adapted to partly or entirely intercept the pencil of rays in response to external pressures applied thereto. Any change in the earth's crust in a direction to cause a landslide causes the shading mechanism to operate in correspondence with the magnitude of the change so as to partly intercept the parallel pencil of rays and cause a change in the quantity of light detected, making it possible to obtain a quantitative knowledge of the change in the earth's crust.

Abstract: A color image reading apparatus comprises a plurality of line sensors, an optical system for forming an image of a subject, a blazed diffraction grating inserted in light path between the optical system and the sensors, and a slit inserted in light path between the subject and the optical system. The blazed diffraction grating separates light beams from the subject into plurality color lights and directs them to their corresponding sensor arrays. The slit has an aperture, the size of which in the array direction of the sensors is longer than that in the direction perpendicular to the array direction of the sensors. By construction of the apparatus according to the present invention, noise light can be prevented so as to read high accuracy digital color image.

Abstract: The spectrometer permits transmission and emission measurements to be made selectively and accurately without extinguishing the internal radiation source. It includes a device that blocks the divergent source-beam radiation that would otherwise corrupt the emission signal received by the detector.

Abstract: A photographic scanner has a light source for illuminating a photographic original to be scanned and a sensor for detecting light which has passed through the original. The sensor has a single row of sensing cells, and the original is scanned by moving the sensor and the original relative to one another in a direction perpendicular to the row. An objective serves to focus light from the original on the sensing cells. Between the objective and the sensor is a protective glass sheet which overlies the sensor. A mask is interposed between the protective sheet and the sensor and has a slit in register with the row of sensing cells. The mask reduces the amount of scattered light reaching the sensing cells.