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DE-102024133136-A1 - Optical sensor

DE102024133136A1DE 102024133136 A1DE102024133136 A1DE 102024133136A1DE-102024133136-A1

Abstract

An optical sensor comprises at least one measuring mirror that is pivotable over a predetermined range, a measuring light source configured to emit a measuring light beam in the direction of the measuring mirror, at least one position-determining mirror that is pivotable together with the measuring mirror, and a position-determining light source configured to emit a position-determining light beam in the direction of the position-determining mirror. The optical sensor further comprises a receiving element configured to detect the position-determining light beam reflected from the position-determining mirror, and an evaluation unit configured to determine the orientation of the measuring mirror with respect to at least one reference direction based on the position of the detected position-determining light beam at the receiving element and on the relative spatial arrangement of the receiving element with respect to the position-determining mirror.

Inventors

  • Christoph Jürgens
  • Gregor Huber

Assignees

  • SICK AG

Dates

Publication Date
20260513
Application Date
20241113

Claims (11)

  1. Optical sensor (200) comprising: at least one measuring mirror (226) that is pivotable over a predetermined range, a measuring light source configured to emit a measuring light beam in the direction of the measuring mirror (226), at least one position determination mirror (228, 229) that is pivotable together with the measuring mirror (226), a position determination light source (210) configured to emit a position determination light beam (212) in the direction of the position determination mirror (228, 229), a receiving element (230) configured to detect the position determination light beam (212) reflected from the position determination mirror (228, 229), and an evaluation unit (240) configured to orient (α) the measuring mirror (226) relative to at least one reference direction (232) based on a position (P a ) of the detected to determine the position determination light beam (212) at the receiving element (230) and based on the relative spatial arrangement of the receiving element (230) in relation to the position determination mirror (228, 229).
  2. Optical sensor (200) according to Claim 1 , wherein the at least one measuring mirror (226) and the at least one position determining mirror (228, 229) are attached to a common support (224) and arranged in the same plane (225).
  3. Optical sensor (200) according to Claim 1 or 2 , wherein the at least one measuring mirror (226) and the at least one positioning mirror (228, 229) are formed as respective areas of a single, contiguous mirror surface.
  4. Optical sensor (200) according to one of the preceding claims, wherein a single position determination mirror (228) is provided.
  5. Optical sensor (200) according to one of the Claims 1 until 3 , wherein at least two positioning mirrors (228, 229) are provided which are spatially separated from each other.
  6. Optical sensor (200) according to one of the preceding claims, comprising a polygon mirror (250) with at least three facets (260, 270), whereby a respective measuring mirror (226) and a respective position determining mirror (228) are formed on each of the three facets (260, 270) of the polygon mirror (250).
  7. Optical sensor (200) according to one of the preceding claims, wherein the receiving element (230) comprises at least one sensor row.
  8. Optical sensor (200) according to one of the preceding claims, wherein the measuring mirror (226) and the position determining mirror (228) are jointly pivotable in two mutually perpendicular directions and the receiving element (230) comprises at least two sensor rows.
  9. Optical sensor (200) according to Claim 7 or 8 , wherein at least one of the sensor rows (230) is curved.
  10. Optical sensor (200) according to one of the preceding claims, wherein a cylindrical lens is arranged between the position determining mirror (228) and the receiving element (230).
  11. Optical sensor (200) according to one of the preceding claims, wherein the measuring light source and the position determination light source (210) are identical.

Description

The invention relates to an optical sensor with a movable measuring mirror that can be pivoted over a predetermined area. Optical sensors can use movable measuring mirrors to acquire measurement data at different spatial positions. Examples of such sensors include 2D and 3D lidar systems and other optoelectronic sensors. Based on the acquired measurement data, these sensors can detect objects in space and determine their spatial orientation, i.e., their distance relative to the sensor and one or more angles relative to a reference direction in space. However, especially when the distance between an object whose spatial location is to be determined and the sensor is large, the angle at which the sensor detects the object should be known as precisely as possible in order to resolve objects with a desired precision and to determine their spatial location or position with a specified accuracy. Known optical sensor systems use, for example, an encoder rigidly connected to the movable measuring mirror to determine the angular deflection of the movable measuring mirror relative to a reference direction. For instance, a reflective encoder disk can be attached to a rotatable measuring mirror. Such known sensor systems with a rotatable measuring mirror and an encoder disk attached to it achieve, for example, an angular resolution of between 1° and 2°, which corresponds to the distance between lines on the encoder disk. With such known optical sensors with a movable measuring mirror, the angle of the measuring mirror relative to a reference direction cannot be measured directly, but only the angle of the encoder disk attached to the measuring mirror relative to a reference position. Other well-known angle measurement techniques also generally do not allow for a direct measurement of the angle by which a movable measuring mirror is currently deflected. With such indirect measurements of the angle by which the movable measuring mirror is deflected, several measured quantities must consequently be combined, which limits the accuracy of the angle measurement due to error propagation or tolerance chain. However, preventing or subsequently compensating for such a reduction in accuracy when determining the angle of a movable measuring mirror, for example by means of calibration, usually requires considerable effort if a predetermined high accuracy in the angle measurement is desired. One object of the invention is to determine the instantaneous angle of the measuring mirror relative to a reference direction directly and with high precision in an optical sensor with a movable measuring mirror. This problem is solved by an optical sensor having the features of claim 1. Advantageous embodiments of the invention are specified in the dependent claims, the description, and the drawings. The optical sensor according to the invention comprises a measuring mirror that is pivotable over a predetermined range, a measuring light source configured to emit a measuring light beam in the direction of the movable measuring mirror, a position-determining mirror that is pivotable together with the measuring mirror, and a position-determining light source configured to emit a position-determining light beam in the direction of the position-determining mirror. The optical sensor further comprises a receiving element configured to detect the position-determining light beam reflected from the position-determining mirror, and an evaluation unit configured to determine the orientation of the measuring mirror with respect to at least one reference direction based on the position of the detected position-determining light beam at the receiving element and on the relative spatial arrangement of the receiving element with respect to the position-determining mirror. The measuring light source and the position-determining light source can each be a laser, emitting a laser beam in the direction of the movable measuring mirror and the movable position-determining mirror, respectively. The optical sensor can be a 2D or 3D lidar sensor that uses such a laser as its measuring light source. Advantageously, the measuring light source and the position determination light source are formed by the same light source. To allow the positioning mirror to be pivoted together with the measuring mirror, the movable measuring mirror and the movable positioning mirror are coupled with each other in their movement. This ensures that the measuring mirror and the positioning mirror pivot synchronously. For example A synchronous rotation around a common axis of rotation takes place. This ensures that the orientation or rotation angle of the measuring mirror can be derived from, or corresponds to, the orientation or rotation angle of the positioning mirror. Thus, the orientation of the measuring mirror, i.e., its current rotational position, can be determined based on the current orientation or rotational position of the positioning mirror. The measuring mirror and the positioni