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
  • G01B11/08—Measuring arrangements characterised by the use of optical techniques for measuring diameters

Definitions

• the present invention relates to apparatus for measuring the dimensions of cylindrical objects, by means of a scanriing laser beam.
• Apparatus for measuring the diameter of cylindrical ob ⁇ jects such as axles, tubing, piping and the like are known to the art.
• the objects are measured with the aid of a laser beam, which co-acts with a rotating mirror or prism.
• a lens sights the beam, the beam is sighted onto the objects by means of a lens, such, that said beam sweeps over the object being measured in mutually paral ⁇ lel paths.
• the beam transmitted by the measuring apparatus shall mo ⁇ ve with rotation of the mirror, so that the beam constant- ly lies parallel with the optical axis of the system.
• the object of the present invention is to eliminate the aforedescribed difficulties.
• an apparatus for measuring the dimensions of cylindrical objects with the aid of a scanning laser beam, which is directed from a source of laser ligh onto a rotating mirror and through a first lens located a focal-length distance from the centre of rotation of the mirror, the beam being arramged to sweep over one side of the object and to be reflected by the rotating mirror to a light detector arranged to control a data processor which determines and indicates the sen- sed dimension, the apparatus being mainly characterized by means arranged to direct the beam towards and to sweep over the other, opposite side of said object.
• the data processor being arranged to formulate the mean va- lue of the measuring values sensed on said first and said second side of the object, and in that the mirror is re ⁇ flective on both sides thereof and the laser beam, during one half of a revolution of said mirror is arranged to be directed by said mirror through a first system of fi ⁇ xed irtirrors onto said first lens so as to sweep across one side of the object; in that the beam is arranged to be directed towards the detector via a second lens which is located on the opposite side of the object to be measu- red and a second system of fixed mirrors via the rotating mirror; and in that the beam during the subsequent half revolution of the rotating mirror is directed onto the other side of the object vid said second system of fixed -mirrors and said second lens, the beam being directed on- to the detector via the first lens and said first system via the rotating mirror.
• a laser 1 arranged to trans ⁇ mit a laser beam onto a rotatable mirror 2, which is re ⁇ flective on both sides thereof.
• the scanning beam reflec ⁇ ted by the mirror 2 is deflected by a series of fixed mir- rors 3,4 and 5 onto a lens 6.
• the lens 6 is arranged to cause the beam to scan an object 7 to be measured in mu ⁇ tually parallel paths. Due to the spherical aberration of the lens, the beam will not scan in precisely parallel directions, and hence the beam will be delected slight- ly in the direction indicated by A in the drawing.
• Drawn on the object to be measured is a coordinate system XY.
• the measurement value When the object 7 is moved in the direction -X the measurement value will be too small, while when the object is moved in the direction +X, the measurement value will be too large.
• the measurement error only occurs in one zone of the measuring area.
• One prerequisite is that the rotating mirror 2 lies in the focus of the lens 6 for that part of the beam which may be otherwise bypass the lens.
• That 'light which passes to one side of the object 7 is collected by a lens 8 located opposite the lens 6, and is directed onto mirrors 9,10 and onto a photo detector 11 located adjacent of the rotating mirror 2 which is loca ⁇ ted opposite at that moment.
• the photo detector 11 is arranged, in a known manner, to control a data processor 12, for example analogously with vhat is described in the aforementioned Swedish Published Specification, and hence this part of the apparatus is not shown in detail on the drawing.
• the mirror 2 is reflective on both si ⁇ des and the rotary movement of the mirror causes the beam which impinges on the photo detector to be stationary.
• the beam generated by the laser 1 will be reflected onto the mirrors 10 and 9 and through the lens 8, from where it is directed onto the object 7 to be measured.
• the lenses 8 and 6 are mutually similar.
• the lens 6 receives the light and di ⁇ rects it through the mirrors 5,4,3 onto the opposite side of the rotating mirror 2, which reflects it onto the pho ⁇ to detector 11.
• the object to be measured is scanned by the laser beam from two different directions, and the error is eli ⁇ minated by formulating a mean value in the data processor.
• the schematically illustrated data processor 12 is intended to represent synchronizing means, pulse-generating and pulse-receiving means, indi ⁇ cating means and pulse-counting means, for example in the manner described in the aforementioned Swedish Published Specification No. 7812400-5.

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

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Publications (1)

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ID=20346916

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Country Status (6)

Cited By (2)

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Citations (2)

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• 1982
  • 1982-05-28 SE SE8203310A patent/SE430924B/sv not_active IP Right Cessation
• 1983
  • 1983-05-26 JP JP58501846A patent/JPS59500927A/ja active Pending
  • 1983-05-26 WO PCT/SE1983/000209 patent/WO1983004303A1/en active IP Right Grant
  • 1983-05-26 EP EP83901748A patent/EP0110937B1/en not_active Expired
  • 1983-05-26 DE DE8383901748T patent/DE3367278D1/de not_active Expired
  • 1983-05-26 US US06/584,950 patent/US4561778A/en not_active Expired - Fee Related

Patent Citations (2)

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