Abstract: A docking adapter for reliably inserting and removing a memory storage device from a memory storage device bay includes a rack and a removable carrier. The rack has a pair of lateral rails for holding the carrier. The carrier slidably engages the rails to enable the carrier to slide into the rack. The carrier is adapted for holding a hard disk drive. The carrier has a face with cooling fans, a cantilever mounted on the face for engaging the rack and a cover with a cam. The cover is hinged to the face. The cover rotates from a closed position where the cover parallels the face to an open position where the cover opens, pressing the cam against the cantilever against the rack to smoothly extract the carrier from the rack.

Abstract: A color cathode ray tube comprises a vacuum vessel including a panel portion having a phosphor screen on its inner face, a neck portion and a funnel portion joining the neck portion and the panel portion. An inline electron gun is disposed inside of the neck portion and includes a main lens and cathode producing a center electron beam and two side electron beams. A deflection yoke for deflecting the electron beams and a pair of 2-pole ring magnets for adjusting electron beam trajectory are disposed around the neck portion. The 2-pole ring magnets have a magnetic flux density distribution at a circle which is concentric with the ring magnets, wherein the radius of the circle corresponds to the distance between adjacent electron beams at the main lens. The ratio of the amplitude of the flux density in the radial component compared to the amplitude of the flux density in the circumferential component is 0.86 to 1.38 on the circle.

Abstract: A cathode ray tube includes a phosphor screen and an electron gun. The electron gun includes an indirectly heated cathode structure and plural grid electrodes arranged in axially spaced relationship. The cathode structure includes a base metal having an electron emissive material coating and a heater for heating the base metal. The heater includes a major heating portion having a spirally wound heating wire and a pair of leg portions connected to opposite ends of the major heating portion. The major heating portion and an inner portion of each of the leg portions on a major-heating-portion side thereof are covered with an insulating coating, and the heater is welded to electrical conductors for applying a voltage thereto at an outer portion of each of the leg portions, the outer portion not being covered with the insulating coating.

Abstract: An apparatus is provided for estimating the service life of a battery. The apparatus includes a temperature measurement circuit that measures a temperature of an operating environment of the battery and outputs a signal representative of the temperature of the operating environment. A controller coupled to the temperature measurement circuit receives the temperature signal therefrom and estimates the service life of the battery based on the temperature signal. Preferably, the temperature measurement circuit outputs a signal representative of a temperature range in which the measured operating environment temperature resides and the controller estimates the service life of the battery based on the temperature range signal output by the temperature measurement circuit. A method and a computer program product also are provided for similarly estimating the service life of a battery.

Abstract: A battery charger monitors an open-circuit voltage across the battery and the rate of change of temperature of the battery to determine a time to terminate the process of charging the battery. Charging proceeds in four stages. In the first stage the open-circuit voltage of the battery is monitored until such voltage crosses a threshold value. In the second stage, the rate of change of battery temperature is monitored to determine a reference value, for example, a minimum of the monitored rate. In the third stage, the rate of change of battery temperature is again monitored to identify a time when such rate exceeds the reference value by a predetermined amount. In the fourth stage, power supplied to charge the battery is limited immediately after stage three or a predetermined time after stage three for example by reducing the charging current to a trickle-charge level or by reducing the voltage by about 100 mV.

Abstract: A method and apparatus for compensating, consistent with variations in cooling conditions, protection and limit functions of a generator. Limits of the capability curve of the generator, including the overexcited region, underexcited region and region limited by stator current heating, are modified in response to changes in coolant pressure or temperature depending on the type of generator being compensated. Feedback signals and setpoints being provided to fixed protection and limit functions are intercepted and modified in accordance with the relationship between generator rated values and generator performance in view of altered coolant conditions. Protection and limit functions are automatically coordinated. As a result, overall generator performance is improved.

Abstract: A power converter includes first and second voltage busses and a neutral bus. A first switching circuit, e.g., a rectifier circuit, is operative to selectively couple an input node thereof to the first and second voltage busses. A balancer circuit is operative to selectively couple the neutral bus to the first and second voltage busses such that relative magnitudes of respective first and second voltages on the first and second voltage busses are controlled responsive to respective first and second rates at which the balancer circuit couples the first and second voltage busses to the neutral bus. A second switching circuit, e.g., an inverter circuit, is operative to selectively couple the first and second voltage busses to a load connected at an output node thereof.

Abstract: An ultra high frequency current probe is fabricated in the form of a surface mount device, designed to be a part of the circuit providing the current being observed.

Abstract: A device for testing a conductor for the presence of high AC voltage includes a voltage detection circuit connected to a probe assembly, preferably designed for insertion in the access bushing of an underground electrical transmission or distribution equipment. The probe assembly includes an elongated tubular insulating housing with a conductive probe at one end and a threaded connector at the other end for connection to the detection circuit. A high resistance, preferably several megohms, is connected in series between the tip and the connector and is preferably comprised of a plurality of series-connected resistors encased in a heat shrink tubing.

Abstract: A wafer probe station is equipped with an integrated environment control enclosure substantially surrounding a supporting surface for holding a test device, such enclosure limiting fluid communication between the interior and exterior of the enclosure and preferably also providing EMI shielding and a dark environment. The limited communication between the interior and exterior of the enclosure is kept substantially constant despite positioning movement of either the supporting surface or probe holders. The positioning mechanisms for the supporting surface and probe holders each have portions located at least partially outside of the enclosure for transferring movement mechanically to the surface or holders, respectively.

Abstract: A magnetic sensor utilizing a giant magnetoresistance (GMR) effect, wherein an insulation layer with a contact hole is formed on a lower terminal layer, a GMR layer is formed thereover on the region including the entire contact hole and at least the surrounding insulation layer, and an upper terminal layer is formed thereover. The sensor offers several advantages in that it is easy to manufacture and is compact, and has a high degree of resistance change.

Abstract: A position detection apparatus which can control an apparatus to be controlled, such as a motor or the like, more precisely, is disclosed. When a predetermined time has passed since reception of a request signal for requesting output of the position data was detected, the position detector measures the output of a sensor for detecting the position of an object to be measured, and calculates the position data representing the position of the object at a point of time when the measurement was performed, based on the measured output.

Abstract: An integrated circuit device structure having probe pad extensions in electrical communication with the wire bond pads and a method for performing failure analysis thereon. The invention provides an improved probing system for wire bond packages such that neither the wire nor the wire bond from the pads on the chip surface need be removed during testing procedures. Included in the integrated circuit device is a plurality of conductive pads having a first area for receiving a wire bond and a second area for receiving a probe, wherein the second area abuts, and is an electrical communication with the first area.

Abstract: A test carrier for testing a semiconductor component includes at least one decoupling capacitor for reducing parasitic inductance and noise in test signals transmitted to the component. The carrier includes a base, an interconnect for making temporary electrical connections with the component, and a force applying mechanism for biasing the component against the interconnect. The decoupling capacitor can be mounted to the base, or to the interconnect, with electrodes of the capacitor contained in power and ground paths to the component. A test method includes the steps of providing the carrier with the decoupling capacitor, assembling the component in the carrier, and transmitting test signals through the decoupling capacitor to the component. A test system includes the test carrier, a test apparatus such as a test board, and test circuitry for generating and analyzing test signals.

Abstract: In a frequency-voltage conversion circuit, integrating means gives a predetermined slope for rising or falling of a rectangular pulse signal. First comparing means compares an output value of the integrating means with a threshold value, and produces a pulse signal line having a pulse width corresponding to frequency of the rectangular pulse signal. Storing means stores and retains the threshold value. Smoothing means smooths the pulse signal line, and produces a voltage value corresponding to the frequency of the rectangular pulse signal. Second comparing means compares the voltage value with a reference voltage, and charges and discharges electric charge for the storing means on the basis of the comparison result.

Abstract: A charge pump system includes a charge pumping circuit for outputting a high voltage VPP at a node. An oscillator circuit, coupled to the charge pumping circuit, drives the charge pumping circuit with at least one clock signal. A current source generates a pulldown current. A voltage divider circuit is coupled between the node and the current source. The voltage divider circuit cooperates with the current source to form a feedback loop for controlling the oscillator circuit to run at variable, optimum frequency for controlling the rate-of-rise and the amplitude of the high voltage VPP while minimizing power-supply current drain.

Abstract: In order to stably generate a high voltage of a prescribed level, a Vpp detection circuit which is activated in response to an activation signal for comparing the high voltage with a reference voltage is forcibly brought into an active state for a prescribed period under control of an initial control circuit.

Abstract: A signal processing circuit is described including a frequency selective network in a feedback loop. An analog-to-analog converter in the feedback loop is coupled to the frequency selective network. A continuous-time feedback path provides feedback from the output terminal of the analog-to-analog converter to the frequency selective network.

Abstract: A signal processing circuit and method for processing an input signal are described. The circuit includes a frequency selective network, an amplification stage, and at least one continuous-time feedback path from the output of the amplification stage to the frequency selective network. The amplification stage includes a switching amplifier and an analog amplifier. Switching circuitry alternately enables the switching and analog amplifiers for processing of the input signal.

Abstract: A high power amplifier has a first balun propagating a half of an input signal to an in-phase output terminal, and also propagating a fourth of the input signal to first and second opposite-phase output terminals, the signal propagated to the first and second opposite-phase output terminals lagging 180 degrees behind the signal propagated to the in-phase output terminal; first and second power amplifier circuits connected to the first and second opposite-phase output terminals of the first balun and having the same characteristics; a third power amplifier circuit connected to the in-phase output terminal of the first balun and having output power substantially twice as much as the output power of the first or second power amplifier circuit; and a second balun having first and second opposite-phase input terminals for receiving the outputs of the first and second power amplifier circuits, having an in-phase input terminal for receiving the output of the third power amplifier circuit, combining the outputs of t

Abstract: A positive thermistor device includes a positive thermistor element having a pair of opposed electrodes, each of which receives compressive force elastically applied from a corresponding one of spring contact members to hold the thermistor element at a predefined position in the device. When the thermistor device is destroyed, the element breaks into fragments, some of which remain in contact with the spring contact members. The remaining fragments deviate in position to ensure that they do not conduct electricity, resulting in an open state, wherein any current flow is inhibited through such fragments. More specifically, a positive thermistor disk is held within the device so that it is interposed between conductive spring contact pieces and insulative position-alignment projections, which are cross-diagonally situated with respect to each other.

Abstract: A semiconductor device die comprising one or more stress-isolated regions is described. In one embodiment, stress isolation is achieved by providing a nominally rigid rim region which forms part of the stress isolated region. The rim region is attached to a nominally rigid periphery or frame region by a flexible, spring-like stress-isolation region such that displacements and twisting of the frame region due to mounting and packaging stresses are mitigated, do not propagate to the stress-isolated region, and do not effect the output signal. The stress isolation flexible region includes first and second members etched from the semiconductor device material to mechanically isolate the diaphragm from its periphery. The first member is formed by etching a first deep trench. The combination of the first deep trench etch and a second deep trench etch define the second member. In one embodiment, the stress-isolated region comprises a pressure-sensitive deformable diaphragm for sensing pressure.

Abstract: A ceramic thermistor chip has outer electrodes electrolytically formed on both end parts of a ceramic thermistor element and the portions of the surface of the ceramic thermistor element not covered by these outer electrodes are entirely covered by an organic insulating layer such as an acrylate resin layer or a ceramic layer with specific resistance greater than that of the thermistor element such as a material having as its principal component one or more oxides containing two or more metals selected from Mn, Ni, Co, Fe, Cu and Al and one or more metals selected from Zn, Al, W, Zr, Sb, Y, Sm, Ti and Fe.

Abstract: A portable handheld computing device has a notification system that alerts a user of an event regardless of whether the device is on or off. The notification system has a notification mechanism that is activated upon occurrence of the event and remains active until the user acknowledges the activated mechanism. In one implementation, the notification mechanism is a light emitting diode (LED) mounted externally on the handheld computing device. The LED is visible to the user when the lid is closed onto the base (i.e., the device is off) or when the lid is open (i.e., the device is on). The notification mechanism also has a deactivation button mounted externally of the handheld computing device. The user depresses the deactivation button to deactivate the LED. The LED and deactivation button may be integrated as a single component.

Abstract: A communications system including a radio frequency identification device including an integrated circuit having a single die including a microprocessor, a receiver coupled to the microprocessor, and a backscatter transmitter coupled to the microprocessor, the integrated circuit having a digital input, and the receiver being configured to receive wireless communications from a remote interrogator; and an analog to digital converter external of the single die and having a digital output coupled to the digital input of the integrated circuit, and having an analog input configured to be coupled to an analog measuring device, wherein the radio frequency identification device is configured to transmit a signal indicative of the analog input using the backscatter transmitter. A communications method including coupling an analog to digital converter to a radio frequency identification device.

Abstract: A holder is eliminated when installing an antenna to a radio case, the installation operation is simplified, and a feeding mechanism is improved. A slit is provided in a stopper of an antenna so that the outer diameter can be reduced, and the antenna is inserted directly into a cylindrical section of the radio case from the bottom of the stopper. A plate-like feeding spring is provided at the cylindrical section, and is directly attached to a connection point of a circuit substrate of a radio; one end of the plate-like feeding spring pressingly contacts the side of the stopper of the antenna, thereby forming a feeding mechanism.

Abstract: The present invention comprises a novel system for authoring and publishing hypermedia works. The present invention includes a scrollable contents map window in which a graphical representation of a hypermedia work is displayed. The contents map window contains graphical lexia symbols representing the lexia of the hypermedia work, empty space, and other graphical and text elements. Links between lexia are not ordinarily displayed. Selecting a lexia symbol causes the corresponding lexia to be displayed in a lexia display window. The lexia symbols representing lexia may be arranged in the window in any configuration. Freely movable text labels and other graphical elements may be placed anywhere in the contents map window. Additional special purpose graphical elements may be placed in the contents map window to create relationships among lexia. In one embodiment, a number of different modes of the contents map window can be displayed. One mode is a caricature mode.

Abstract: A system and method for augmenting data and for integrating the augmented data into a program running on a computer system is provided. The invented system couples to a data collection computer along with data generating equipment, such as a body suit, for augmenting data generated thereby. Augmentation data generated by the system and body movement data generated by the suit is simultaneously transmitted to the computer containing a data base defining a virtual world. As the suit generates movement data and transmits the data to the computer for controlling the movements of an object in the virtual world, an operator of the system monitors the data generated by the equipment and activates the system to selectively augment data generated thereby, for enhancing the movements of the character. The invented system transmits the augmentation data to the data collection computer to augment the data generated by the equipment so that the character, has exaggerated movements or cartoonish features.

Abstract: A film is made of an elastic material. The film is stretched in at least one direction in parallel to a surface of the film. Then, through-holes are punched in the film be means of needles, in a state the film is stretched. After the punching is completed, the stretching is terminated, so that the film recovers its original shape.

Abstract: In a print head of this invention, electricity-to-heat converters and a driver circuit for driving these electricity-to-heat converters in accordance with print data are formed on a single board. The board further includes an input/output interface circuit for receiving print data from an external apparatus, a CPU for controlling a printer apparatus, a ROM, a RAM, an A/D converter, a D/A converter, a timer, and the like, and also includes an external element driver for driving a mechanism portion of the printer apparatus.

Abstract: A flexible frame onsert molded capping system has an elastomeric sealing lip onsert molded onto a flexible, flat, springy support frame, preferably with series of these sealing lips being molded on a single flexible frame to simultaneously seal several adjacent inkjet printheads. The frame has a border region with one or more cap bases attached to the frame by plural suspension spring elements. The suspension spring elements have both cantilever and torsional characteristics which allow the bases to tilt and twist independent of one another to seal each printhead, even when the orifice plates of adjacent printheads are not in a coplanar alignment. Use of a single piece frame, and onsert molding of the cap lips thereon, decreases the number of parts required to assemble an inkjet printing mechanism, leading to a more economical unit which is easier to assemble.

Abstract: An inkjet printing method of fixing ink to a print medium is disclosed. An embodiment of the method comprises depositing ink drops on a print medium with an inkjet printhead, the ink including a solvent and the print medium including a first surface. The method additionally comprises vibrating the print medium by applying ultrasonic energy to displace drops of the solvent to the first surface of the print medium to accelerate evaporation of the drops of solvent. An apparatus for use in an inkjet printing device is also disclosed. An embodiment of the apparatus comprises an ultrasonic source configured to apply ultrasonic energy to a print medium to displace drops of ink solvent to a first surface of the print medium thereby accelerating evaporation of the drops of solvent. An inkjet printing device including the method and apparatus is also disclosed. Further characteristics and features of the method and apparatus are described herein, as are examples of various alternative embodiments.

Abstract: A method of detecting a breach of security in a first location and providing information about the breach of security to security personnel in a remote location is provided. The method includes acquiring global positioning signals at the first location upon the breach of security and transmitting the global positioning signals to the remote location. Personnel at the remote location are thus notified of the breach of security and also are provided the position of the first location for taking action appropriate to the breach.

Abstract: An imaging device comprises a semiconductor substrate including an array of pixel cells. Each pixel cell comprising an individually addressable pixel circuit for accumulating charge resulting from radiation incident on a pixel detector. The pixel circuit and the pixel detector can either be implemented on a single substrate, or on two substrates bonded together. The charge storage device can be a transistor, for example one of a pair of FET transistors connected as a cascade amplification stage. An imaging plane can be made up of one imaging device or a plurality of imaging devices tiled to form a mosaic. The imaging devices may be configured as a slot for certain applications, the slit or slot being scanned over the imaging plane. Control electronics can include addressing logic for addressing individual pixel circuits for reading accumulated charge from the pixel circuits.

Abstract: A method for controlling behavior of a digital camera is disclosed. The method detects connectivity to a universal serial bus (USB) and automatically switches to a corresponding mode of operation depending on the result of the detecting.

Abstract: A separator circuit receives a stream of data including both audio and video components. The separator circuit separates the audio and video components for transmission to appropriate devices. In the preferred embodiment, the separator circuit is part of a decompression engine which decompresses the received stream of data and also separates the audio and video components. Preferably, the decompression engine is implemented within a device configured for coupling to an IEEE 1394-1995 serial bus network. Alternatively, the decompression engine is implemented as a separate dedicated device within the IEEE 1394-1995 serial bus network. After separating the audio and video components, one or both of those components are transmitted from the decompression engine over one or more isochronous channels on the IEEE 1394-1995 serial bus, to the appropriate devices.

Abstract: In a display unit for a motor vehicle, a display (2) designed as an LCD is arranged in the same plane as a dial plate (1) of a pointer-type instrument. For this purpose, the dial plate (1) has a cutout into which the display (2) is bonded. This makes the display (2) and the dial plate (1) particularly easy to read.

Abstract: A directional display comprises a display arrangement such as a spatial light modulator and a rear parallax barrier illuminated by a suitable backlight. The spatial light modulator and the parallax barrier cooperate to produce Fresnel diffraction which results in spatially non-uniform brightness across viewing windows of the display. Also, where the spatial light modulator has pixels of non-constant vertical aperture, further variations in the intensity profile at the windows occurs. In order to compensate for this, a mask is provided, for instance between the parallax barrier and the backlight. The mask cooperates with the parallax barrier to produce an intensity pattern having variations which are the inverse of the variations in intensity pattern produced by the parallax barrier and the spatial light modulator. The variations are superimposed and substantially cancel each other out so as to result in viewing windows which have substantially uniform light intensities.

Abstract: Apertures are formed in the common electrode or in the pixel electrode of a liquid crystal display to form a fringe field. Storage capacitor electrodes are formed at the position corresponding to the apertures to prevent the light leakage due to the disclination caused by the fringe field. The apertures extend horizontally, vertically or obliquely. The apertures in adjacent pixel regions may have different directions to widen the viewing angle.

Abstract: A liquid crystal display device includes first and second substrates, a plurality of gate bus lines and data bus lines on the first substrate, the gate bus lines being perpendicular to the data bus lines, a plurality of pixels defined by the gate bus lines and the data bus lines, the pixels having a plularity of regions, at least a pair of electrodes in each region having a common direction, and a plurality of liquid crystal molecules between the substrates.

Abstract: In a first aspect this invention provides a security article comprising an electrically actuated optical switch comprised of a liquid crystal material. In one embodiment the liquid crystal material is disposed in a layer of polymer dispersed liquid crystal material. In a second embodiment the liquid crystal material is microencapsulated with an orientable dye. In a second aspect this invention provides a document or currency that comprises a paper matrix that includes at least one security article, i.e. a security thread. In a third aspect this invention provides a device for verifying an authenticity of a document or currency of a type that includes at least one security article, i.e. at least one security thread. The at least one security thread includes the liquid crystal material having a visual characteristic that is switched between two states as a function of a presence or absence of an electric field between first and second electrodes.

Abstract: Disclosed is an optically corrected lens for nonprescription eyeglasses. In a preferred embodiment, the anterior surface of the lens lies on a portion of a first sphere having a first center. The posterior surface of the lens lies on the surface of a second sphere having a second center. The first and second centers are offset from one another to provide a tapered lens. The lens is oriented on the head of the wearer by a frame that maintains the lens in a position such that a line drawn through the first and second centers is maintained substantially in parallel to the normal sight line of the wearer. Lenses are thus provided which have improved optics when mounted in an as-worn orientation such that they exhibit both vertical “rake” and horizontal “wrap.” Methods of making the lenses, and eyewear incorporating the lenses, are also disclosed.

Abstract: A method of exposing an alignment mark defined in a first side of a semiconductor wafer includes the step of engaging a second side of the wafer with a wafer chuck. The method also includes the step of positioning the wafer in a chamber having a photochemical reactant gas present therein during the engaging step. Moreover, the method includes the step of impinging laser beams on the first side of the wafer such that a reactant specie is generated from the photochemical reactant gas. Yet further, the method includes the step of removing material from the first side of the wafer with the reactant specie. An apparatus for exposing an alignment mark defined in a first side of a semiconductor wafer is also disclosed.

Abstract: A lens specifying apparatus comprising a light source (21) for projecting a measuring light beam on a lens (30) under examination, an area CCD (35) image receiving element for receiving the measuring light beam transmitted by the lens (30) under examination, a filter disc (64) disposed, as means for providing spectral transmittances, at a midpoint of an optical path extending from the light source (21) to the area CCD (35), and a processing circuit (37) for calculating the refractive characteristics and spectral transmittances of the lens (30) under examination on the basis of an output of the area CCD (35) and displaying the refractive characteristics and spectral transmittances on a monitor (3).

Abstract: The present invention enables measurement of the configuration of a pattern with irregularity in a wide surface region with a high accuracy and in a single operation by using an apparatus having relatively simple construction.

Abstract: Systems and methods for laser capture microdissection are disclosed. A method of laser capture microdissection includes providing a sample that is to undergo laser capture microdissection; positioning said sample within an optical axis of a laser capture microdissection instrument; providing a transfer film carrier having a substrate surface and a laser capture microdissection transfer film coupled to said substrate surface; placing said laser capture microdissection transfer film in juxtaposition with said sample with a pressure sufficient to allow laser capture microdissection transfer of a portion of said sample to said laser capture microdissection transfer film, without forcing nonspecific transfer of a remainder of said sample to said laser capture microdisection film; and then transferring a portion of said sample to said laser capture microdissection transfer film, without forcing nonspecific transfer of a remainder of said sample to said laser capture microdissection transfer film.

Abstract: The present invention is directed to a system for converting between single flow and split flow evaporative light scattering detection devices for detecting samples in a mobile phase. Included in the system is a evaporative light scattering detection device, a low temperature adaptor, and a connection tube for providing a fluid connection between the evaporative light scattering detection device and the low temperature adaptor.

Abstract: A sensor system for determining the position of at least one edge of a web of material traveling along a predetermined path. The sensor system has a transmitter assembly capable of selectively transmitting at least one collimated light curtain and a receiver assembly capable of generating output signals in response to receiving portions of the collimated light curtain transmitted by the transmitter assembly. The receiver assembly is spaced a distance from the transmitter assembly so as to define a travel path therebetween whereby at least a portion of the web of material traveling along a predetermined travel path blocks at least a portion of the collimated light curtain transmitted by the transmitter assembly. The output signal generated by the receiver assembly is indicative of the position of the web of material as the same is moved along the travel path between the transmitter assembly and the receiver assembly.

Abstract: An exposure apparatus includes a projection optical system, a barrel supporting member for supporting the projection optical system, a stage being movable relative to the projection optical system, a base for supporting the stage, a base measuring system for measuring at least one of a position and a displacement of the base with respect to the barrel supporting member, and a stage measuring system for measuring at least one of a position and a displacement of the stage with respect to the barrel supporting member.

Abstract: A 3-D range sensor for measuring range from the sensor to a target surface by imaging a plurality of points projected onto the target surface is disclosed. The range sensor comprises an optical system for imaging a first image and a second other image of each of the plurality of points on the target surface, whereby the second other image is obtained from a different predetermined location than the first image. The optical system comprises an optical medium for combining the first image and the second other image, at least a reflective means for imaging at least one of the first and the second other image and for reflecting it to the optical medium such that the first image and the second other image are combined and a converging lens system for focussing the first image and the second other image. A position sensitive light detector detects the focussed first image and the focussed second other image.