EP0200723A1 - Methode de mesure par ligne de collimation - Google Patents

Methode de mesure par ligne de collimation

Info

Publication number
EP0200723A1
EP0200723A1 EP19840904206 EP84904206A EP0200723A1 EP 0200723 A1 EP0200723 A1 EP 0200723A1 EP 19840904206 EP19840904206 EP 19840904206 EP 84904206 A EP84904206 A EP 84904206A EP 0200723 A1 EP0200723 A1 EP 0200723A1
Authority
EP
European Patent Office
Prior art keywords
axis
target surface
laser tube
laser
centre
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19840904206
Other languages
German (de)
English (en)
Inventor
Svante BJÖRK
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Svante Bjork AB
Original Assignee
Svante Bjork AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Svante Bjork AB filed Critical Svante Bjork AB
Publication of EP0200723A1 publication Critical patent/EP0200723A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
    • G01B11/27—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes
    • G01B11/272—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes using photoelectric detection means

Definitions

  • a method of line-of-sight measurement such as alignment, straightness, level, position and similar measurements, include the use of a narrow beam of light, such as a laser beam, and photoelectric detector means adapted to intercept the beam and to provide an output indicative of the position where the beam impinges on a target surface of the detector means.
  • a narrow beam of light such as a laser beam
  • photoelectric detector means adapted to intercept the beam and to provide an output indicative of the position where the beam impinges on a target surface of the detector means.
  • the beam is caused to orbit along a circular path on the target surface, and the position of the centre of the circular path is determined on the basis of the length of time the beam illuminates each of a number of segments of the target face during one full cycle of the orbital movement (US-A-3 790 276) .
  • the accuracy of such measurements is dependent on the magnitude of the deviation of the actual position of the axis of the beam from the nominal or supposed position.
  • the beam is a laser beam
  • the axis of the beam is typically supposed always to coincide with the axis of a cylindri- cal housing containing the laser tube and to be parallel with a reference plane or line of a support or mount for the housing. In actual practice, however, the actual position deviates from the nominal position.
  • One cause of such deviation may be instability of the beam with respect to the laser tube. Even if the laser tube is mounted and aligned very accurately, the axis of the beam may thus be offset in an uncontrolled manner from the axis of the laser tube.
  • Another cause may be misalignment of the laser tube with respect to a housing in which the laser tube is fixedly secured. Such misalignment may be caused by deformation resulting from thermal stresses.
  • An object of the present invention is to reduce substantially or eliminate the influence on the measurement result of any deviation of the actual position of the beam axis from the nominal position.
  • a method of line-of-sight measurement in which a narrow beam of light, such as a laser beam, is projected onto a target surface of a photoelectric detector device and caused to orbit along a circular path on the target surface and in which the position of the centre of the circular path is determined, characterised in that the light beam is caused during each completed cycle of its orbital movement to rotate at least a full turn relative to the target surface.
  • a narrow beam of light such as a laser beam
  • the combined rotational and orbital movement may be accomplished simply by rotating the laser tube at a speed substantially higher than the rate at which any uncontrolled changes of the deviation of the actual beam axis position from the nominal beam axis position occur.
  • the centre of the orbital path then will be located on the axis of rotation of the laser tube which axis may be presumed to be stable. Because an offsetting of the beam axis from the axis of rotation is unavoidable in actual practice, the rotation of the laser tube will automatically result in the combined orbital and rotational movement of the beam on the target face.
  • the laser tube or a housing in which the laser tube is fixedly secured may be attached to a rotatable support, such as a spindle of a machine tool.
  • the rotational movement may also be accomplished with a stationary source of the beam by positioning a rotating prism (Dove prism) in the beam path.
  • Dove prism rotating prism
  • Fig. 1 is a diagrammatic representation of a first embodiment comprising a rotating laser tube
  • Fig. 2 is a diagrammatic representation of a second embodiment comprising a non-rotating laser tube and a beam-rotating prism.
  • a laser tube A is fixedly secured within a cylindrical tubular housing 11 which is mounted in bearings 12 for rotation about an axis C.
  • the bearings 12 are mounted on a support S carrying a motor D for rotating the housing 11 at suitable speed. It is here presumed that the axis C coincides with the axis of
  • the axis L of the laser beam B includes a small angle with the axis C.
  • This angle may vary somewhat in operation, e.g. because of thermal drift or deformations resulting from thermal stresses. However, any variations are presumed to be slow in relation to the rotational speed of the housing 11 so that the angle may be considered to be constant over any series of, for example, five or ten successive revolutions. A smaller or larger portion of the angle may be due to misalignment of the laser tube A with respect to the housing 11.
  • the numerical value of the angle included between the axes L and C need not be known. Moreover, the angle need not exist intentionally, the offsetting of the beam axis L from the axis C may be the result of the unavoidable manufacturing and assembling tolerances and changes occurring in operation, such as thermal drift.
  • the beam B impinges on a target surface T of a photoelectric detector 13.
  • the target surface T which is generally perpendicular to the axis C, is provided by four contiguous planar photodetector elements 13A,13B,13C, 13D having one point 13E in common.
  • the illuminated spot S on the target surface T orbits along a circular path P having its centre M positioned on the axis C.
  • the centre M is situated at a distance from the common point 13E of the detector segments.
  • the spot S rotates with respect to the target surface T such that it completes one full revolution for each full cycle of the orbital movement.
  • Electrical output signals produced by the detector 13 are processed in well-known manner in an associated signal processing device 14 producing an output signal indicative of the position of the centre M of the circular path P with respect to the common detector segment point 13E.
  • the determination of the position of the centre M preferably is carried out by successive integration over a series of cycles of the combined orbital and rotational beam movement.
  • the data representing the position of the centre M on the target surface T may be used in different ways, depending on the purpose and nature of the measurement being carried out. For example, in the case of an alignment or position measurement, an adjustable part on which the detector 13 is positioned may be displaced with the guidance of continuously supplied data of the position of the centre M until the centre M coincides with the point 13E.
  • the beam axis L need not include an angle with, or intersect, the rotational axis C.
  • the offsetting of the axes from one another must be limited so that the operative or sensitive portion of the target surface T is capable of intercepting the beam throughout the orbital movement.
  • the embodiment shown in Fig. 2 differs from that shown in Fig. 1 in that rotation of the laser beam B is accomplished by means of a rotating prism 15 and in that the photoelectric detector 13' is of a different type such that the signal processing device 14' directly produces an output quantity indicative of the position of the centre M' on the target surface T' .
  • An example of detectors of this type is the two-dimensional silicon position sensitive detector produced and marketed under the designations S1200 and S1300 by Hamamatsu Photonics K.K., Hamamatsu City, Japan. Naturally, a detector of this type can also be used with the rotating laser arrangement of Fig. 1.
  • the beam-rotating prism 15 is a so-called Dove prism and causes the beam to orbit about the rotational axis C' of the prism and at the same time to rotate about its axis L at a speed twice that of the rotational speed of the prism.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

Dans une méthode de mesure par ligne de collimation à l'aide d'un rayon laser (B) et un dispositif (13) de détection sensible à la position, on fait effectuer au rayon laser un mouvement combiné orbital et de rotation sur une surface cible (T) du dispositif de détection. La position du centre (M) du chemin orbital (P) sur la surface cible est déterminée et utilisée comme point de référence ou de bornage.
EP19840904206 1983-11-10 1984-11-06 Methode de mesure par ligne de collimation Withdrawn EP0200723A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8306188 1983-11-10
SE8306188A SE439197B (sv) 1983-11-10 1983-11-10 Sett for optisk syftningsmetning

Publications (1)

Publication Number Publication Date
EP0200723A1 true EP0200723A1 (fr) 1986-11-12

Family

ID=20353266

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19840904206 Withdrawn EP0200723A1 (fr) 1983-11-10 1984-11-06 Methode de mesure par ligne de collimation

Country Status (3)

Country Link
EP (1) EP0200723A1 (fr)
SE (1) SE439197B (fr)
WO (1) WO1985002253A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9809297D0 (en) * 1998-04-30 1998-07-01 Avolites Limited Method and apparatus for directing a beam of light
DE19943502A1 (de) * 1999-09-10 2001-04-12 Busch Dieter & Co Prueftech Vorrichtung zur Bestimmung der Achslage von Hohlzylindern
CN104677281B (zh) * 2015-03-12 2017-07-11 上海锅炉厂有限公司 空间接管安装测量的方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4006356A (en) * 1961-10-27 1977-02-01 Aeronutronic Ford Corporation Radiant energy tracking device
US3790276A (en) * 1971-04-07 1974-02-05 Us Navy Direct measurement of ship body distortion using a laser beam

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8502253A1 *

Also Published As

Publication number Publication date
SE8306188D0 (sv) 1983-11-10
SE439197B (sv) 1985-06-03
WO1985002253A1 (fr) 1985-05-23
SE8306188L (sv) 1985-05-11

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Legal Events

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19860715

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Inventor name: BJOERK, SVANTE