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EP-4741762-A1 - APPARATUS FOR MEASURING A DISTANCE TO A TARGET WITH FINE TUNING

EP4741762A1EP 4741762 A1EP4741762 A1EP 4741762A1EP-4741762-A1

Abstract

Apparatus for measuring a distance between a reference point and a target, the apparatus comprising a distance measuring device including a beam source configured to emit a measuring beam, a detector configured to receive a reflected beam, and a control unit, and a beam forming device including at least one receiving element (R1, R2, R3, R4) configured to adapt the reflected beam, wherein the at least one receiving element (R1, R2, R3, R4) is movable in a motorized manner between a first position, in which the reflected beam is reduced to a first power that is non-zero, and a second position, in which the reflected beam is reduced to a second power that is non-zero, wherein the first power is different from the second power.

Inventors

  • GOGOLLA, TORSTEN
  • WINTER, ANDREAS
  • SANCHEN, GUENTER

Assignees

  • Hilti Aktiengesellschaft

Dates

Publication Date
20260513
Application Date
20241112

Claims (13)

  1. Apparatus (40; 100) for measuring a distance between a reference point (REF) and a target (36-1, 36-2, 37-1, 37-2, 38-1, 38-2), the apparatus (40; 100) comprising: ▪ a distance measuring device (41) including a beam source (43) configured to emit a measuring beam (44), a detector (45) configured to receive a reflected beam (46), and a control unit (47) configured to determine the distance between the reference point and the target, at which the measuring beam was reflected and formed into the reflected beam, and ▪ a beam forming device (42; 102) including at least one receiving element (R1, R2, R3, R4; 112, 113) configured to adapt the reflected beam, characterized in that the at least one receiving element (R1, R2, R3, R4; 112, 113) is movable in a motorized manner between a first position, in which the reflected beam is reduced to a first power that is non-zero, and a second position, in which the reflected beam is reduced to a second power that is non-zero, wherein the first power is different from the second power.
  2. The apparatus of claim 1, wherein, while moving the at least one receiving element (R1, R2, R3, R4; 112, 113) from the first position to the second position, the power of the reflected beam that is received at the detector (45) is non-zero for positions between the first position and second position.
  3. The apparatus of any one of claims 1 to 2, wherein the at least one receiving element (R1, R2, R3, R4; 112, 113) is configured to be arranged in a starting position, in which the power of the reflected beam at the detector (45) is non-zero, and configured to have a surface area arranged in the reflected beam that is increasing, when the receiving element (R1, R2, R3, R4; 112, 113) is moved from the starting position in a first direction (75), and a surface area arranged in the reflected beam that is decreasing, when the receiving element is moved from the starting position in a second direction (76) opposite to the first direction (75).
  4. The apparatus of claim 3, wherein the at least one receiving element has a dynamic of change that is a progressive change, when moving in the first direction or second direction.
  5. The apparatus of any one of claims 1 to 4, wherein the at least one receiving element (R1, R2, R3, R4) is formed as a pattern of openings.
  6. The apparatus of any one of claims 1 to 5, wherein the at least one receiving element (R1, R2, R3, R4; 112, 113) includes a first receiving element (R1; 112) configured to adapt the reflected beam to a first type of targets and/or to a first range of distances, and a second receiving element (R2; 113) configured to adapt the reflected beam to a second type of targets and/or to a second range of distances.
  7. The apparatus of claim 6, wherein the at least one receiving element further includes a third receiving element (R3) configured to adapt the reflected beam to a third type of targets and/or to a third range of distances.
  8. The apparatus of any one of claims 1 to 7, wherein the beam forming device (42; 102) further includes at least one transmitting element (T1, T2, T3, T4; 116, 117) configured to adapt the measuring beam, the at least one transmitting element (T1, T2, T3, T4; 116, 117) is movable in a motorized manner between a first position and a second position that is different from the first position.
  9. The apparatus of claim 8, wherein the at least one transmitting element includes a first transmitting element (T1; 116) configured to adapt the measuring beam (44) to a first type of targets and/or to a first range of distances, and a second transmitting element (T2; 117) configured to adapt the measuring beam (44) to a second type of targets and/or to a second range of distances.
  10. The apparatus of claim 9, wherein the at least one transmitting element further includes a third transmitting element (T3) configured to adapt the measuring beam (44) to a third type of targets and/or to a third range of distances.
  11. A method for measuring a distance between a reference point and a target (36-1, 36-2, 37-1, 37-2, 38-1, 38-2) using the apparatus (40; 100) according to any one of claims 1 to 10, the method is performed by a computer system of the apparatus (40; 100) and comprises the following steps: ▪ Instructing the apparatus (40; 100) to arrange the at least one receiving element () in a starting position, ▪ Instructing the distance measuring device (41; 101) to measure the distance between the reference point and the target, and ▪ Evaluating the measurement of the distance by comparing the power of the reflected beam received at the detector with a lower limit and an upper limit.
  12. The method of claim 11, wherein the method is continued, if the power of the reflected beam received at the detector is below the lower limit or above the upper limit.
  13. A computer program comprising instructions, which, when executed by a computer system, cause the computer system to carry out the method for measuring a distance between a reference point (REF) and a target (36-1, 36-2, 37-1, 37-2, 38-1, 38-2) according to any one of claims 11 to 12.

Description

Technical field The present invention relates to an apparatus for measuring a distance between a reference point and a target according to the definition of claim 1, to a method for measuring a distance between a reference point and a target according to the definition of claim 12 and to a computer program according to the definition of claim 13. Background of the invention Surveying instruments are known to assist in critical building and construction functions. For example, building foundations and retaining walls must be engineered and constructed within a certain degree of accuracy if they are to perform their desired functions in a proper manner and maintain structural integrity over time. Surveying instruments, such as total stations, robotic total stations, theodolites, laser beam measuring instruments, and similar instruments are often used to achieve the desired degree of accuracy and precision for these features and operations. Surveying instruments usually include an apparatus for measuring a distance that provides a capability of measuring a distance between a reference point of the surveying instrument to a target with a measuring beam; the measuring beam can be a laser beam that is visible or infrared. Surveying instruments usually measure distances to retro-reflective targets, such as retro-reflective prisms, retro-reflective cat-eyes or retro-reflective foils, or to natural targets. To measure distances to retro-reflective targets, the power that is received at a detector has to be reduced, wherein the necessary reduction differs for the different types of retro-reflective targets (retro-reflective prisms, retro-reflective cat-eyes and retro-reflective foils) and for different ranges of distances (near, middle and large). From prior art, different beam forming devices are known to reduce the power of the measuring beam and/or the power of the reflected beam in order to avoid overdriving of the detector. US 10,788,581 B2 and US 10,908,284 B2 disclose beam forming devices that include different forming elements that are adapted to different types of retro-reflective targets (retro-reflective prisms, retro-reflective cat-eyes and retro-reflective foils) and different ranges of distances. The forming elements include a receiving element to adapt the reflected beam and/or a transmitting element to adapt the measuring beam. Drawback of the beam forming devices known from prior art is that each forming element has fixed forming properties. In order to change the forming properties, it is necessary to switch between the forming elements and arrange another forming element in the beam path of the reflected beam and the measuring beam. It is time consuming to identify the best forming element for a specific target and a specific distance, and there is a need for a beam forming device that allows to adapt the power that is received at the detector easier. Summary of the invention The present invention has been made with the above-described background in mind, and it is, therefore, an object of the present invention to propose a beam forming device that allows to adapt the power that is received at the detector with less effort. These objectives are achieved by realizing the features of the independent claims. Features which further develop the invention in an advantageous manner are described in the dependent claims. According to an aspect of the present invention, there is provided an apparatus for measuring a distance between a reference point and a target, the apparatus comprising a distance measuring device and a beam forming device including at least one receiving element configured to adapt the reflected beam, characterized in that the at least one receiving element is movable in a motorized manner between a first position, in which the reflected beam is reduced to a first power that is non-zero, and a second position, in which the reflected beam is reduced to a second power that is non-zero, wherein the first power is different from the second power. The at least one receiving element is configured as a forming element for the reflected beam. The term "reflected beam" is used for the measuring beam coming from the target. The target, at which the measuring beam is reflected, can be a retro-reflective prism, a retro-reflective cat-eye, a retro-reflective foil or a natural target. In case of a retro-reflective target, the reflected beam is a retro-reflected beam, and in case of a natural target, the reflected beam is a back scattered beam. The receiving element can be formed as an aperture for the reflected beam that reduces the power of the reflected beam and thereby the power that is received at the detector of the distance measuring device. When the receiving element is arranged in the beam path of the reflected beam, the reflected beam can only partly transmit the receiving element. The power received at the detector can be adapted by changing the part of the surface area of the receiving elem