Abstract: A beam divider which is particularly intended for use in smoke measuring apparatus comprises a transparent beam dividing plate (11) which is obliquely arranged in the beam path and is partially silvered at its lower side (11'). Two protective plates (13, 14) which form a closed internal space (12) leave the upper side of the beam dividing plate (11) above and below the optically active region. At least the protective plate (13) which crosses the beam path is transparent and the arrangement is closed in a dust-tight manner at the end faces.

Abstract: An optical electronic monitoring apparatus is used to detect undesired coil or lap formation at transport and drive rollers 13. For this purpose the beam 14 of a light barrier is arranged along the surface of the roller 13 parallel to its axis 23 in such a way that it is partially obscured by the cross-section of the roller. The subsequent evaluation circuit has a low pass filter 16, a differentiation stage 17 and a further low pass filter 18.

Abstract: A reflection light barrier for recognizing also strongly reflecting articles has at one side of a monitored region a light transmitter (13) which is combined with a light receiver (12) and, at the other end of the monitored region, a reflecting device (11). The reflecting device (11) has optical filter characteristics so that the spectral distribution of the light beam is changed on reflection. An electronic processing circuit only produces a signal following the incidence of reflected light on the receiver when the spectral distribution does not correspond with the spectral distribution of light reflected from the reflecting device.

Abstract: A laser beam scanning device (17) is provided for monitoring for thread breakage in tufting machines (31) in which a carrier web (16) is passed from below to a spiked roller (11) and is deflected by the spiked roller into a substantially horizontal direction so that it can be passed beneath a row of needles (12). The row of needles (12) periodically introduce threads into the carrier web (16) by up and down movement in order to form tufted material. A narrow retro-reflecting strip (14) is arranged directly below and behind the tips of the needles and directly above the tufted material (15) parallel to the row of needles (12) and substantially at right angles to the surface of the tufted material.

Abstract: Faults in a material web are detected by scanning the web with a beam of light along a line transverse to its direction of movement and by detecting the angular ranges into which the incident light is scattered by these faults. For this purpose a light conducting rod is arranged parallel to the scanned line in a reception plane. The light conducting rod has a stepped prism arrangement along its side surface opposite to the light inlet and the inclination of the individual, unmirrored, prism surfaces is such that specularly reflected light passes through the prisms whereas scattered light falls on the prism surfaces at angles of total reflection and is reflected to a photodetector at an end face of the light conducting rod.

Abstract: An elongate resilient section at the closure edge of a closure movable to close an opening contains at least one electrical switching strip 11 which is arranged in an associated hollow cavity (13, 14; 113) close to the elongate securing block (28; 120) used to secure the resilient section to the closure edge. The resilient section is so constructed that the electrical switching strip or strips (11; 11, 12) is actuated not only by compressive forces acting in the direction of closure but also by forces acting sideways on the resilient section.

Abstract: An electronic apparatus has an input stage (11) with a binary signal output (19). This signal output is connected to a relay control circuit which deenergizes or energizes the relay (15) in dependence on the output signal (0 or 1). The relay (15) can be held in the energized condition over a wide voltage range, without being overloaded, by a periodically limited energizing current. This is achieved, by way of example, by energizing the relay via a semiconductor switching device (transistor 14) which can be switched on and off by a Schmitt trigger (12) connected to the binary signal output. A capacitor (17) charged in dependence on the energizing current flowing through the relay is used to override the signal from the binary output (19) to switch the transistor (14) via the Schmitt trigger (12) so as to periodically energize the relay (15) (FIG. 1).

Abstract: Fault detection apparatus for material webs comprising a light transmitting device for generating a line of light on the material web and an elongate light receiving device which extends parallel to the line of light and is so arranged that it can receive light which enters a predetermined reception plane from the line of light, with the predetermined reception plane lying at a specified angle to the plane normal to the material web and containing the line of light, and with the line of light being formed by a bead of light which scans the web point by point, line by line. The light receiving device (43) comprises a plurality of light receivers (1 to 30) which can be selectively switched in, with at least one of the light receivers being switched out at each particular instant.

Abstract: A fault seeking apparatus for detecting faults in carpet webs (15) has a first main mirror wheel (17) which is illuminated by a laser beam (18) and which generates via a concave mirror (13), a scanning beam (14) which is periodically displaced parallel to itself. This scanning beam is directed at an angle to several subsidiary mirror wheels (11a to 11i) which are arranged alongside one another, which rotate substantially faster than the main mirror wheel (17) and which generate a scanning light strip on the carpet web (15). A light receiving device consisting of lenses (20a to 20i) arranged alongside one another and a light conducting rod (22) with a photomultiplier (23) at one end face is arranged on the other side of the carpet web (15) (FIG. 1).

Abstract: Pulsed light barrier apparatus is driven directly from an a.c. supply voltage connected to the terminals L and M with the terminal M being earthed. A storage capacitor 14 is charged during the positive half wave of the a.c. supply voltage and is discharged at a time determined by a programmable unijunction transistor 13 through a photodiode 11 to emit a flash of light which passes across a region monitored by the light barrier to a photoreceiver 26. A Zener diode limits the voltage across the storage capacitor 14 to a value less than the peak a.c. supply voltage. As soon as the voltage across the storage capacitor has reached the Zener breakdown voltage the excess energy from the a.c. supply voltage is directed through a rectifier diode 18 to a smoothing capacitor 19 where it forms a positive operating voltage for the light receiver arrangement. During the negative half wave of the a.c.

Abstract: A retroreflector consists of a support surface 12 coated with a layer 11 of small retroreflecting particles such as glass spheres. The support surface comprises a plurality of regularly repeating, alike, structural elements 13 which are inclined to the overall plane of the retroreflector. The surface elements 13 can be of various shapes and serve to increase the angular range over which retroreflection can occur. The optical characteristics of the proposed retroreflectors can be tailored so that they are eminently suitable for use in certain beam scanning applications such as continuous monitoring of doorways and windows by an optical beam scanning device located at one corner thereof in order to detect, for example, intruders.

Abstract: The present spectrometer features two modulators 11, 11' disposed one on either side of a dispersive member 19 which produces wavelength dependent deflections .alpha. of the various spectral components in the radiation. In other words the precise angle of deflection .alpha. is a function of wavelength. The dispersive element 19 is conveniently positioned between two lenses 26 which form a telecentric system with a magnification of one. The lens system is used to produce an image of the first modulator on the second modulator. Each of the modulators is preferably a grating with a linearly varying grating constant so that the modulators, which move in opposite directions f,f' at constant speed subject the incident radiation to a position dependent modulation. The radiation emerging from the second modulator 11' falls onto a photodetector 13.

Abstract: A light collecting arrangement particularly for use with beam scanning apparatus for monitoring for faults in web material has a diffraction grating 11 and a light collecting surface usually in the form of photoelectric converter 19 arranged at right angles to the diffraction grating 11. The characteristics of the diffraction grating 11 are so selected that only light incident within a predetermined range is deflected to the light collecting surface. A number of different arrangements are disclosed. The light collecting arrangement can, for example, be used with a scanning light beam which is continuously displaced parallel to itself to effect point by point line by line scanning of the web material 17 or can take the form of a scanning light beam which executes a sector-like scanning movement.

Abstract: A mixture of substances is analyzed by spectral analysis to establish the concentration of one component of the mixture. For this purpose signals U.sub.1 (.lambda.) representative of the spectrum of the substance under investigation and U.sub.2 (.lambda.) representative of the spectrum of the mixture of substances are manipulated electronically so as to remove the effects of cross-sensitivity and to yield an accurate value for the concentration of the substance in the mixture of substances. This concentration is normally difficult to determine because of the effects of cross-sensitivity, i.e. because other components in the mixture of substances have similar spectral lines to those of the substance under investigation. In one arrangement the two signals U.sub.1 (.lambda.) and U.sub.2 (.lambda.) are first differentiated in respective differentiating stages 13 and 14 and the differentiated signals are multiplied in a multiplier 17.

Abstract: Faults in a material web 47 are detected by scanning the web with a beam of light 37 along a line transversely to its direction of movement F and by detecting the angular ranges into which the incident light is scattered by these faults. For this purpose an elongate light receiving device 33, which is preferably a light conducting rod, extends parallel to the line of scanning on the web with the axis of the light conducting rod and the line of scanning defining a reception plane. An elongate angular range filter 34 is arranged in this plane between the line of scanning and the light conducting rod and serves to deflect beams of light 35 close to the angle of specular reflection away from the light conducting rod. Light which is scattered in other angular ranges within the reception plane is however transmitted by the angular range filter 34 to the light conducting rod and is detected by a photoelectric detector positioned at the end face thereof.

Abstract: Spectral analysis of a beam of radiation is carried out by splitting the beam of radiation into its respective spectral components and by applying a characteristic modulation to each of the spectral components before allowing them to fall on a common detector. The super-imposed signals generated by the detector and representative of the spectral components are then electronically segregated by reference to the characteristic modulations that have been applied to the individual spectral components. This is conveniently done by generating a series of modulated reference signals which have been modulated in exactly the same way as the spectral components of interest. The technique is not restricted to optical spectra but can also be used, for example, for X-ray spectra and mass spectra.

Abstract: Piezoelectric light deflecting apparatus consists of first and second piezoceramic strips 11, 12 each of which has a clamped end and a free end 15. The strips 11, 12 are substantially aligned in one plane with their free ends 15 facing one another and spaced apart by a distance x. An AC voltage U having a frequency which differs significantly from the natural resonant frequency of the strips is used to energize the strips to execute oscillations so that their free ends are periodically displaced in counterphase to one another. A mirror 13 is mounted via flexible legs 14 to the free ends of the piezoceramic strips 11, 12 so that the mirror 13 executes a rotary oscillation as a result of the counterphase movements of the free ends of the piezoceramic strips.

Abstract: A light beam 2 from a laser light source 30 is split by a beam splitting arrangement 21, 22 into two slightly convergent light beams which are deflected by a deflecting mirror 31 onto the surface of a mirror wheel 23. The mirror wheel 23 that deflects these light beams via deflecting mirrors 24', 25' onto two strip-like concave mirrors 24, 25 which produce respective parallel scanning light beams which are continuously displaced parallel to themselves in the image spaces of the strip-like concave mirrors. These scanning light beams fall on respective rows of inclined dividing mirrors 9 and 10 which are arranged one behind the other in an alternating sequence. The inclined mirrors deflect the incident light beams through substantially 90.degree. to form a continuous light curtain which can be used to scan web material.

Abstract: Apparatus for measuring the speed of flow of a flowable medium by determining the transit time of sound waves therein wherein first and second sound transmitter/receivers in the form of electroacoustic converters are spaced apart in the medium with an imaginary line joining said first and second transmitter/receivers having a component in the direction of the flow to be measured and wherein sound pulses of predetermined length are alternately transmitted in a first direction from said first transmitter/receiver to said second transmitter/receiver and in a second direction opposite to said first direction from said second transmitter/receiver to said first transmitter/receiver said sound pulses being converted into electrical measurement pulses on arrival at said transmitter/receivers there being processing circuitry for processing electrical measurement pulses to determine the speed of flow from the transit times of the sound pulses in said first and second directions, said processing circuitry including mean

Abstract: Light curtain apparatus incorporating a cyclical scale generator has a light transmitter 12 which projects a light beam onto an optical scanning device 13 located at the focal point of a strip-like concave mirror 14. As a result a parallel scanning light beam 20, which is continuously displaced parallel to itself, is produced in the image space of the concave mirror 14. The scanning light beam 20 is directed through a monitored region 17 towards a retro-reflector 16 and light returned from the retro-reflector 16 is passed via a beam divider 27 to a first light receiving device 18. In this way interruption of the light beam, for example by an object 31, results in interruption of the signal from the first photoelectric receiving device 18.