Abstract: A light beam is repeatedly deflected in the longitudinal direction through a holographic element HOE by means of a rotating multi-faceted mirror. This HOE is so formed that the beam entering at different angles leaves the HOE as a telecentric beam. Through a further HOE the telecentric beam is diffracted onto an opto-electric transducer. In the region of the telecentric beam is located an object to be measured, and the time of the interruption of the telecentric beam by means of this object enables the dimension of the latter to be determined. The production of the telecentric beam and the deflection of the latter onto the transducer by means of the HOE allows a simple cost-effect manufacture as well as a simple evaluation of the measurements with increased precision. The manufacture of the HOE is likewise simple.

Abstract: A light beam is repeatedly deflected in the longitudinal direction through a holographic element HOE by means of a rotating multi-faceted mirror. This HOE is so formed that the beam entering at different angles leaves the HOE as a telecentric beam. Through a further HOE the telecentric beam is diffracted onto an electro-optic transducer. In the region of the telecentric beam is located an object to be measured, and the time of the interruption of the telecentric beam by means of this object enables the dimension of the latter to be determined. The production of the telecentric beam and the deflection of the latter onto the transducer by means of the HOE allows a simple cost-effect manufacture as well as a simple evalution of the measurements with increased precision. The manufacture of the HOE is likewise simple.

Abstract: An apparatus for the non-contacting measurement of rod-shaped objects contains a telecentric, F-theta-corrected objective which comprises two catadioptric elements. The first catadioptric element is a Mangin mirror and the second catadioptric element is a plane plate mirror-coated at the front, while a third optical element is a meniscus lens. The use of catadioptric elements permits a simplified and inexpensive form of construction which is also compact, as a result of which objects with large dimensions can be measured quickly and accurately. Such an apparatus serves, in particular, for the continuous control of the production of filament-shaped objects.

Abstract: In a method of checking the insulating sheath on a wire or cable leaving an extruder, the external diameter of the insulating sheath is continuously determined over the whole circumference by means of a first measuring apparatus and the wall thickness of the insulation is continuously detected over the whole circumference by means of a second measuring apparatus. The measured values are supplied to a computer which, inter alia, continuously determines the difference between the maximum and minimum wall thicknesses found (W.sub.max -W.sub.min). Eccentricity and minimum wall thickness of the sheath are calculated from this difference and from the measured external diameter of the insulation and the diameter of the conductor of the wire or cable, and are indicated in a display device. The measurement is thus rendered largely independent of fluctuations in sensitivity of the measuring apparatus for the wall thickness of the insulation.

Abstract: An image of a moving object with an optically differentiatable structure is projected onto a grid of opto-electric transducers through a lens. The output signals of at least one square group of four transducers A-D are processed to produce from output signals of the respective transducers a pair of signals I=A+B-C-D and II=B+C-A-D. The nature of the object is such as to cause periodically varying signals in the transducers, and there are thus concerned two signals shifted by a quarter period, from which the direction of movement can be determined by means of a logic circuit. From the frequency of the signals the velocity can be ascertained. By means of direction dependent counters the path of the object can be determined from the signals. With a two dimensional matrix of transducers measurements can be effected of movement of the object in different directions. The measurement is simple and offers versatile possibilities of exploitation.

Abstract: In a device for the production of a telecentric light beam which is to be deflected over a defined region an incident light beam impinges upon a rotating plane mirror. The light beam reflected thereby reaches the outlet of the device by way of a further co-rotating parallel plane mirror as a telecentric light beam. There is thus obtained by simple optical means a deflection over a region which is considerable in comparison with the dimensions of the device, and the shifting of the deflected light beam occurs according to a simple mathematical function, more especially a sine function. This simple mathematical relationship of a rotary angle and a displacement of the light beam enables an especially simple evaluation of measurement data.

Abstract: In a process and device for measuring the specific capacity of an electric cable by means of a cylindrical measuring electrode through which the cable is passed and between which and the cable conductor an alternating voltage is maintained, the capacitative current flowing between the cable conductor and a defined length of the electrode is determined by measurement of the currents flowing in the cable conductor at respective points located adjacent the ends of the defined length of the electrode, and obtaining the difference between the currents. This avoids the need for direct measurement of the capacitative current and thus enables screening electrodes at each end of the measuring electrode to be directly electrically connected to or integral with the measuring electrode so that they can be maintained at the same potential as the measuring electrode without the need for special electrical circuitry.

Abstract: For the measurement of a dimension of an object in a liquid, windows are provided in a vessel containing the liquid and the object, and parts of an optical measuring apparatus for the determination of the dimension of the object are arranged in the region of the window. This measuring arrangement can be fitted on to an existing installation without substantial expense. An open vessel, into which the object must be inserted, thus remains freely accessible. Since the window is constantly in contact with the liquid, no optical interruptions can occur which would falsify the measurement.

Abstract: In a process for the measurement of absolute values by means of a non-linearly working measured value emitter, calibration of the measuring device is achieved by determining, for each of a range of measured values emitted, the corresponding absolute values, by means acting independently of the output signal of the measured value emitter, and storing each of the determined absolute values in a store at addresses defined by the measured value, and during a subsequent measuring process the store is interrogated by means of measured value information whereby the stored absolute values are determined. There is also described an apparatus for carrying out the process.

Abstract: An apparatus for testing the wall thickness of a moving tube of plastics or other electrically non-conducting material being produced by an extruder, comprises an electrically conductive measurement body arranged in the moving tube, a ferromagnetic holding member which is arranged in the tube within effective range of a holding magnet located outside the tube and which has a tie connection to the measurement body to locate the measurement body axially within the effective range of a measuring sensor located outside the tube. The holding member and the measurement body may be introduced into the tube through a channel in the extruder head, shot into the tube from a forward position, or inserted through an aperture cut in the tube wall.

Abstract: A device for the measurement of the wall thickness of tubes, in particular for the measurement of extruded synthetic tubes during the extrusion process, comprises a common support for location within the tube and a plurality of measuring bodies mounted on the support and urged resiliently outwards for engagement with the tube wall. In order to provide a sufficiently robust support for the measuring bodies they are connected to the support by means of a parallelogram linkage, and in order to allow the measuring bodies a degree of free movement so that they can conform to the contour of the tube wall at least one parallelogram arm of the parallelogram linkage is pivoted with free play.

Abstract: Apparatus for measuring the wall thickness of a moving tube, for example an extruded tube of synthetic plastics material, comprises means for location in a stationary position within the tube and adapted to present at least one measuring body in resilient contact with the inner wall of the tube, and an external sensor for sensing the position of the measuring body. A mechanical linkage incorporating means engaging the tube wall is arranged to lift the measuring body away from the tube wall when excessive friction between the tube wall and the engagement means indicates a condition liable to damage the measuring body.

Abstract: An apparatus for producing identical flat carriers each having an identical representation thereon, by the steps of providing a plurality of individual representations on a flat material in a predetermined mutual relationship, providing at least two reference marks on the flat material in predetermined relationship with respect to the representations, mounting the flat material carrying the representations in a preset position relative to a punch device by means of the reference marks and successively punching out the individual carriers from the flat material by the punch device.