Leica Geosystems Ag

Albert Markendorf

Raimund Loser

Burkhard Böckem

Jürgen Dold

Bernhard Hauri

Roland Zumbrunn

Konrad Wildi

Andreas Christen

Stephen Kyle

Some embodiments of the invention relate to a laser tracker for continuously tracking a reflective target and for determining the position of the target, comprising a base that defines a vertical axis and a beam-deflecting unit for emitting measurement radiation. The beam-deflecting unit can be pivoted about the vertical axis and a tilt axis in relation to the base in a motorized manner and a measurement axis is defined by an emission direction of the measurement radiation. The laser tracker may have a fine distance measurement unit for precisely determining a distance to the target, an angle measurement functionality for determining an orientation of the beam-deflecting unit in relation to the base, and a target-seeking unit. The target-seeking unit has illuminating means, a camera having a position-sensitive detector for detecting illumination radiation reflected by the target, and a control and evaluating unit having seeking functionality for finding the target.

Laser tracker having target-seeking functionality

Some embodiments of the invention relate to a laser tracker for determining the position of a target, comprising a beam source for generating measurement radiation; a base; a beam deflection unit which can pivot with respect to the base &#x2212;4&#xb0; C. about two axes in a motorized manner, for the emission and alignment of the measurement radiation and to capture at least one part of the measurement radiation reflected onto the target; a first position-sensitive surface detector and an evaluation and control unit for determining a point of impact of the reflected measurement on the surface detector for generating an output signal in order to determine the position of said target. Said laser tracker also comprises a calibration device for use with a self calibrating function to determine the calibration parameters thereof with respect to a position and/or direction of the measurement radiation.

Self-calibrating laser tracker and self-calibration method

Some embodiments of the invention relate to a laser tracker for determining the position of a target and in particularly for the continuous tracking of the target. In some embodiments, the laser tracker includes a beam source for generating measurement radiation, an angle measuring function for determining a horizontal pivot angle and a vertical pivot angle, a distance measuring function and a position sensitive surface detector for determining a point of impact of the reflected measurement radiation on the surface detector and for generating an output signal in order to control a target tracking function. The laser tracker may include a self-calibrating function for calibrating a beam offset using a reflecting calibration device.

The invention relates to a method for determining a spatial orientation of an auxiliary measurement object for a laser tracker, said measurement object having reference features which provide points of light. The tracker has a base, a support which can be pivoted in a motorized manner, a pivoting unit which can be rotated about a tilting axis in a motorized manner and which comprises an image capturing unit for capturing an image of the points of light, and a beam source for emitting a laser beam. According to the method, an image is captured in the direction of the auxiliary measurement object with respective capturable points of light, and the spatial orientation of the auxiliary measurement object is derived from image positions in the image for the points of light captured in the image using an image analysis.

Method and device for determining an orientation of an object

Some embodiments of the invention relate to a laser tracker for continuously pursuing a reflective target and for determining the position of the target. The method may include a base which defines a vertical axis, a beam guiding unit for emitting a measurement beam, the beam guiding unit being pivotable by motor relative to the base about the vertical axis and an inclination axis, and a measurement axis being defined by an emission direction of the measurement beam. The laser tracker may include a precision distance measurement unit and an angle measurement function. The target search unit may have illumination source for illuminating the target, a first camera with a first position-sensitive detector and at least one part of the illumination beam reflected on the target being determinable as a first target position, and a control and evaluation unit.

Laser tracker with position-sensitive detectors for searching for a target

A measurement system for determining six degrees of freedom (&#x3b1;, &#x3b2;, d, &#x3c6;, &#x3c7;, &#x3c8;) of a reflector () or of an object () on which the reflector is arranged, comprises an angle- and distance measurement apparatus (), e.g. a laser tracker, operating with a laser beam as a measurement beam (). The reflector () is designed for a parallel reflection of the measurement beam () and has an apical opening or surface (), in a manner such that a part of the measurement beam () directed onto the reflector (), passes through the apical opening or surface (), and is incident on a light-sensitive surface () arranged behind the reflector apex. Five degrees of freedom (&#x3b1;, &#x3b2;, d, &#x3c6;, &#x3c7;) of the reflector () or the object () are computed from measurement data produced by the angle- and distance measurement apparatus () and by the light-sensitive surface ().

Measurement system for determining six degrees of freedom of an object

For indirect determination of point positions and/or of surface orientations in point positions a laser tracker ( ) adapted for relative and absolute distance measurement is used. A measuring device is utilised, the device including a target point (retro-reflector ) for the laser beam of the tracker, the target point being movable along a trajectory path (A). The position and orientation of the trajectory path (A) of the target point is precisely defined relative to a reference point (R) of the device ( ) and the device ( ) is positionable in the region of a point position (P) to be determined such that the position of the reference point (R) relative to the point position (P) to be determined is precisely defined. For determining the point position (P), the device ( ) is positioned in the region of the point position (P) to be determined, the target point is positioned in a starting position ( ) and is detected by the tracker ( ) by direction determination and absolute distance measurement. Then the target point is moved along the trajectory path (A) being followed by the tracker ( ), while direction and distance changes are recorded. In comparison with an indirect determination of a point position with the help of a known measuring tool having a plurality of stationary target points for the tracker beam, the determination by means of the target point moving along the trajectory track (A) is more simple and more accurate.

Indirect position determination with the aid of a tracker

Using a laser-tracker ( ) with an interferometer together with a retroreflector ( ) in the form of a triple prism or a triple mirror arranged on an object and designed for parallel reflection of the laser beam ( ) directed to the reflector ( ), the position of the object is computed by way of measurement data with respect to the direction of the laser beam ( ) and its path length. Additionally the spacial orientation of the object ( ) is determined by producing additional measurement data with respect to the angle of incidence (&agr;) of the laser beam into the reflector ( ) and/or with respect to an adjustable orientation of the reflector ( ) relative to the object ( ) and by computing the position and spacial orientation of the object ( ) by way of measurement data with respect to the direction and the path length of the laser beam ( ) and by way of this additional measurement data. Thereby the measurement data of the direction measurement and of the interferometric measurement may be corrected by way of the additional measurement data with respect to the angle of incidence (&agr;) such eliminating their dependency on the angle of incidence. For determining the angle of incidence (&agr;), the reflector ( ) is designed in a manner such that a central part of the laser beam ( ) passes through the reflector ( ) unreflected and behind the reflector ( ) impinges a position sensor ( ) arranged stationarily relative to the reflector, while a peripheral part of the laser beam ( ) is reflected parallel and used for the interferometric measurement.

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Walde, Switzerland

Albert Markendorf