Laser tracker with functionality for graphical target preparation

Patent metadata

Field	Value
Publication number	US-9612331-B2
Application number	US-201314372717-A
Country	US
Kind code	B2
Filing date	Jan 16, 2013
Priority date	Jan 17, 2012
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

Some embodiments include a laser tracker having: a base defining a standing axis; a beam steering unit for emitting a measurement radiation; a distance measuring unit for determining the distance to the target; and angle measurement functionality for determining an alignment of the beam steering unit. The beam steering unit can swivel around the standing axis and a tilt axis relative to the base. A measurement axis is defined by an emission direction of the measurement radiation. The laser tracker may include a target-seeking unit having lighting means and at least one target-seeking camera having a position-sensitive detector. The one target-seeking field can be illuminated by means of the lighting means. A search image for the position dependent identification of the target can be detected with the target-seeking camera and at least part of the lighting beam reflected on the target can be determined as a search image position.

First claim

What is claimed is:

1. A laser tracker for progressively tracking a reflective object and for determining the position of the object, the laser tracker comprising:
a base defining a standing axis,
a beam deflection unit for emitting measuring radiation and for receiving at least a part of the measuring radiation reflected on the object, wherein the beam deflection unit is pivotable by a motor about the standing axis and an inclination axis relative to the base and a measuring axis is defined by an emission direction of the measuring radiation,
a distance measuring unit for precisely determining the distance to the object by means of the measuring radiation,
an angle measuring functionality for determining an alignment of the beam deflection unit relative to the base,
a target search unit having:
illumination means for generating electromagnetic illumination radiation and
at least one target search camera having a position-sensitive detector,
wherein the target search camera defines a target search field of vision,
wherein the target search field of vision can be illuminated by means of the illumination means,
wherein using the target search camera, a search image can be acquired for the position-dependent identification of targets and
wherein positions of illumination radiation reflections, which are acquired in the search image and represent respective reflective targets, can be identified and determined as search image positions in the search image,

an overview camera,
wherein an overview field of vision of the overview camera overlaps with the target search field of vision,
wherein using the overview camera, an overview image, which at least partially reproduces the visual spectral range, can be acquired for the display for a user, and
wherein the target search camera and the overview camera are arranged in known position and alignment relationship relative to one another, and

a processing unit, wherein the laser tracker has a target provision functionality such that, upon execution of the target provision functionality by the processing unit, graphic markings are incorporated into the overview image by means of image processing as a function of the search image positions, so that the markings represent the targets in the overview image.

2. The laser tracker as claimed in claim 1 , wherein the target search camera is arranged having the optical axis thereof offset to the measuring axis.

3. The laser tracker as claimed in claim 1 , wherein the illumination radiation has a defined illumination wavelength range in the infrared range, and the target search camera is implemented to acquire electromagnetic radiation in a narrowband range, around the defined illumination wavelength range.

4. The laser tracker as claimed in claim 1 , wherein, as a function of the illumination radiation reflections acquired in the search image, a shape and a spatial extension of the targets can be determined and the markings can be displayed in the overview image as a function of the shape and the spatial extension.

5. The laser tracker as claimed in claim 1 , wherein
the target search camera and the overview camera have defined focal lengths that are either identical or constant, and/or
the target search camera is arranged such that its optical axis arranged offset in parallel to the optical axis of the overview camera.

6. The laser tracker as claimed in claim 1 , wherein the target search unit has one further or multiple further target search cameras having respectively a position-sensitive detector and respectively a target search field of vision, wherein the one further or multiple further target search cameras are implemented to acquire electromagnetic radiation in the range around the illumination wavelength range.

7. The laser tracker as claimed in claim 6 , wherein
the target search cameras are respectively arranged with known and fixed position and alignment relationship relative to one another and relative to the overview camera such that
the target search fields of vision of the target search cameras overlap in a shared range of vision with the overview field of vision, and
the optical axes thereof are respectively arranged offset to the measuring axis.

8. The laser tracker as claimed in claim 6 ,
wherein, using each of the target search cameras, respectively a search image having search image positions can be acquired and respective search image positions representing a shared target can be grouped such that coarse distances to the targets can be determined as a function of the grouped search image positions, wherein:
the coarse distances can be linked to respective items of image information of the overview image such that an at least partially perspective environmental image can be generated, and/or
in the scope of the target provision functionality, as a function of the search image positions, the graphic markings are incorporated into the overview image and/or into the at least partially perspective environmental image, wherein the markings are incorporated as a function of the coarse distances.

9. The laser tracker as claimed in claim 1 , wherein the laser tracker has one further or multiple further overview cameras for acquiring one further or multiple further overview images which at least partially reproduce the visual spectral range, wherein a perspective overview image can be generated from the overview image and the one further or the multiple further overview images, and the target provision functionality is configured such that upon execution of the target provision functionality, the graphic markings are incorporated into the perspective overview image.

10. The laser tracker as claimed in claim 1 , further comprising:
a support, which is pivotable by a motor about the standing axis relative to the base and defines the inclination axis, and
a targeting unit, which is implemented as a beam deflection unit and is pivotable by a motor about the inclination axis relative to the support, having a telescope unit for emitting the measuring radiation and for receiving at least a part of the measuring radiation reflected on the target.

11. The laser tracker as claimed in claim 1 , wherein the target provision functionality provides a position-faithful transfer of the search image positions into the overview image and the targets can be displayed in a position-faithful manner in the overview image by means of the graphic markings.

12. The laser tracker as claimed in claim 1 further comprising a control unit for controlling the laser tracker, wherein the control unit has a display unit for the graphic display of the overview image and the markings.

13. The laser tracker as claimed in claim 12 , further comprising a selection function, wherein:
in the scope of the selection function, a desired marking is selectable from the markings incorporated into the overview image by means of the display unit, and/or
a measuring sequence of the targets represented by the markings is definable by means of the selection function.

14. The system as claimed in claim 13 , wherein the targets can be targeted and surveyed in the measuring sequence successively by an alignment of the measuring radiation on the targets.

15. The system as claimed in claim 1 , wherein the overview image is a color image.

16. A target provision method for incorporating graphic markings into an overview image using a laser tracker, the laser tracker comprising:
a base defining a standing axis,
a beam deflection unit for emitting measuring radiation and for receiving at least a part of the measuring radiation

Assignees

• Leica Geosystems Ag

Inventors

• Kwiatkowski Tomasz
• Böckem Burkhard

Classifications

• G01S7/51

  Display arrangements · CPC title

• G01S17/42 Primary

  Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) · CPC title

• G01S17/66

  Tracking systems using electromagnetic waves other than radio waves · CPC title