Abstract: A hydroculture has a feed solution tank 11 from which feed solution is supplied to the plant roots by capillary action or pump action. Feed tubes 12 of a hydrophobic microporous material which is water vapor permeable but not water permeable are laid in this feed solution tank 11, and salt water having a substantially elevated temperature relative to the feed solution is led through the feed tube 12. In this way the used-up feed solution is replaced by desalinated water.

Abstract: The solar mirror apparatus has an elongate support frame on which resiliently flexible sheet metal mirrors (15) are secured in a parabolically curved arrangement, with an elongate solar radiation receiver (28) being mounted at the focal line of the sheet metal mirrors (15). The support frame is swivellable about an axis which extends parallel to the focal line of the parabola. The carrying frame has two spaced apart clamping section supports (11) disposed opposite and parallel to one another. The mirror plates are carried by parabolic webs (13) with the mirror plates being fitted shapewise on the parabolic edges (17) of the parabolic webs (12). The ends of the parabolic webs (12) which extend between the clamping section supports (11) are swivellably supported at the confronting sides of the clamping section supports (11) about swivel axes (14) which extend parallel to the longitudinal axes (13) of the clamping section supports (11).

Abstract: An optoelectric comparison apparatus for structures on plane surfaces or for planar structures has a laser light source 35 the operational light beam of which is split into two component beams 21, 22 by an optical displacement device 26, 25 for laterally displacing part of a beam. These two component light beams 21, 22 impinge on the mirror surfaces of a mirror wheel 11 obliquely to the axis of rotation 20. Two mutually crossed flat first strip mirrors 12, 13 are arranged in the direction of the light reflected from the mirror wheel 11 and each receive only one of the emergent component light beams 14, 15. The emergent component light beams 14, 15 are deflected in substantially opposite directions where, in each case, a further plane second strip mirror 16, 17 is provided which reflects the light to the scanning surface parallel to the light beams 14, 15 which enter into the first strip mirrors 12, 13.

Abstract: An optical fault seeking apparatus has a light scanning apparatus (21) and a light line receiving apparatus (14) which receive the light reflected from the material to be investigated and direct it onto a photoelectric converter. The light beam which forms the light line 11 impinges at an acute angle (.alpha.) onto the surface (13) of the article or web (18) under investigation. The image forming optical light line receiving apparatus (14), effectively consists of two light receivers (14, 14') positioned away from the normally reflected beam (23) and arranged to receive light from respective ones of two spaced apart strip-like regions (11', 11") extending parallel to and partly overlapping the line of light (11). In this way the device is able to detect faults (e.g. lumps or depressions) in fleece-type webs with irregular surface structures which are normally very difficult to monitor with optical fault seeking apparatus (FIG. 1).

Abstract: An elongate retroreflector has a cylindrical lens arrangement (11) and a cylindrical stepped mirror arrangement arranged therebehind, with the axis (M) of the cylindrical stepped mirror arrangement extending parallel to the axis of the cylindrical lens arrangement (11) and lying on the principal plane (H) of the cylindrical lens arrangement, whereas the focal line (f) of the cylindrical lens arrangement (11) is arranged on the stepped mirror arrangement (12).

Abstract: A fault detecting apparatus for flat articles generates a line of light on the article which is imaged onto a photoreceiver via an optical system having cylindrical imaging characteristics. For use with an article 11 having light diffracting characteristics the line of light 12 is arranged substantially at right angles to the structure 13 which causes the light diffraction. The optical system 14 having cylindrical imaging characteristics detects, apart from the zero order at least also the first diffraction order of the light leaving the article. The light of the first diffraction order is also imaged onto its own photoreceiver (FIG. 1).

Abstract: An optical thread breakage monitoring apparatus for tufting machines contains a laser (36), a mirror wheel (17) which is illuminated by the laser and also a plurality of spaced apart strip-like deflecting mirrors (23, 11, 12) which direct the laser light which is cyclically deflected by the mirror wheel (17) onto a horizontally disposed concave mirror (13) which is arranged above the mirror wheel (17) and the deflecting mirrors (11, 12) and which forms the scanning beam (20'") which is directed towards the row of needles (14) of the tufting machine. A retroreflecting strip (15) is arranged behind the row of needles (14). The receipt of the light reflected from the retroreflecting strip (15) takes place in autocollimation (FIG. 1).

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: 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: 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: 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 monitoring for faults in translucent strip material, such as photographic film, comprises a transport device 16, 12, 13, 22 for continuously moving the film 11 in its longitudinal direction and an optical scanning device 23 including a beam divider 21 which divides a single series of scanned light beams 14 into first and second sets of scanned light beams 14a 14b. The first set of light beams 14a is used to carry out transmission measurements on the film as it passes in tensioned condition between two spaced apart rollers 12, 13 and the second set 14b is used to carry out measurements in reflection as the film passes around the surface of a roller 16. The roller 16 has an air permeable surface and air is blown through this surface from the inside of the roller to form an air cushion between the film and the roller.Faults are detected by the electronic processing circuitry 18 in response to variations in the transmission and reflection measurements carried out by the light detectors 15 and 17.

Abstract: A light grid arrangement features a row of light emitting diodes 0 to 9 which are periodically switched on one after the other by a ring counter 11 and are arranged to direct their light through a monitoring region 23 towards an image forming optical means which is conveniently in the form of a concave mirror 24. The light beams are concentrated by the concave mirror 24 onto a photodetector 18 arranged behind a slot aperture 25 located at the focal point of the concave mirror. Missing pulses from the photodetector are detected by processing circuitry 26 to indicate obstruction of the light grid. The width of the slot aperture 25 restricts the width of each individual light beam so that only beams of light from the light emitting diodes that are generally parallel to the axis of the concave mirror are detected. In this way costly optical focussing elements are avoided as are the difficulties of aligning these optical elements with the other optical components of a system.

Abstract: Apparatus for determining faults in strip material is disclosed in this application which enables both color defects and distortions of the surface of the strip material to be recognized.It its general form the apparatus illuminates the material surface at a specific angle with white light and an optical system directs the light leaving the surface to a number of photodetection devices which detect the various angles at which light leaves the surface. The deviations of these angles from the direction of specular reflection, or unimpeded transmission, are characteristic of the nature of the distortion of the surface of the strip material. At least the photodetection device which receives the specularly reflected or normally transmitted light and preferably all the photodetection devices, includes two photodetectors, which detect light in different spectral ranges by means of associated beam splitting and filtering devices. In this way color defects such as stains or spots on the surface can also be recognized.

Abstract: Detection apparatus for finding holes in moving webs uses a row of individual mutually sideways displaced stepped mirror strips in combination with a scanning device which periodically scans a light beam from a laser over the individual mirrors of each strip, to generate a scanning light curtain directed at the surface of a web. A detection device comprising a row of individual Fresnel lenses and associated photoelectronic detectors is arranged parallel to the row of mirror strips to receive light transmitted through any hole present in the web. The individual Fresnel lenses focus any light received onto their associated photoelectric detectors the outputs from which signify the presence of the hole. Means are provided for introducing a degree of divergence into the beams deflected from the stepped mirrors and forming the light curtain whereby the light curtain scans a cross the web without gaps.

Abstract: Apparatus for determining faults on strip material includes a scanning device for linewise scanning of a strip of material with a light beam, a first cylindrical lens extending parallel to the direction of the scanned lines and arranged to image the scanned line on a first cylindrical mirror with its focal line at right angles to the direction of the scanned lines.Faults in the surface of the strip material such as dents, bumps and scratches give rise to characteristic deviations or deflection of the scanning light and the arrangement of the first cylindrical lens and first cylindrical mirror produce a convenient spatial distribution of the light in the image field of the first cylindrical mirror which can be detected by suitably disposed detectors to yield information about the nature and location of the fault. The apparatus includes various other optical components to produce a desired grouping of the deviated light beams to aid their identification and subsequent analysis.

Abstract: A banknote condition monitoring apparatus features a mirror wheel (22) located substantially at the focus of a concave mirror strip (25) with an intervening plane mirror (26) to fold the beam path. The mirror wheel (22) scans an incident light beam from a source (28) to form a transmitted light beam in the image space of the concave mirror (25) which is continuously displaced parallel to itself to and fro through the image space. The transmitted light beam is directed via a cylindrical lens (14) onto the surface of a drum (11) carrying the banknotes (12) to be monitored on its peripheral surface by way of air suction via the channels (32). Light remitted from the surface of the banknote is directed through the lower half of the cylindrical lens (14), impinges on a light conducting rod (15) and is detected at an and face of the light conducting rod by a light receiving device (33).

Abstract: Hole seeking apparatus for material webs is disclosed which features a light source for projecting a light beam onto a mirror wheel arrangement located optically in front of a concave mirror so as to produce a scanning beam in the image space of the concave mirror. The scanning beam is continuously displaced parallel to itself so as to periodically scan along a scanning path on the material web. The mirror wheel arrangement consists of two substantially identical mirror wheels which lie coaxially on one another and which are displaced by a half pitch.The dimensions of the light bead at its point of incidence on the mirror wheels and the optical geometry of the apparatus are selected to avoid light being scattered at an edge of either of the mirror wheels and passing to either side of the web. Scattered light is thus prevented from falling on a light receiving device arranged behind the web and intended to detect the presence of holes therein.

Abstract: The optical apparatus basically comprises a cylindrical lens which gathers light reflected at various angles from a material surface and projects it onto a strip like curved mirror with its axis at right angles to the lens and which subsequently concentrates the light onto a number of photodetectors each of which is associated with a specified range of angles. The light is projected onto the material surface by a scanning device.The arrangement is such that the angle of reflection is determined irrespective of the point along the scanning line at which the scanned beam strikes the material surface.Various arrangements of different types of photodetector devices are described including a matrix of photodetectors, light conducting rods with photodetectors arranged at their end faces and photomultipliers.The apparatus is particularly suitable for monitoring the production of strip metal in strip mills to detect faults in the metal surface.

Abstract: Optical monitoring apparatus for detecting the angles at which light rays leave a material surface scanned by a light bead such as an incident laser beam includes a row of individual Fresnel lenses arranged edgewise directly adjacent each other to focus light leaving the surface onto respective arrays of photodetectors arranged in their focal planes.The outputs from the photodetectors are connected together by processing means to allow evaluation of their output signals. The row of Fresnel lenses may also be used for other optical monitoring purposes.