Laser sensor module with soiling detection

Patent metadata

Field	Value
Publication number	US-2022075042-A1
Application number	US-202117530579-A
Country	US
Kind code	A1
Filing date	Nov 19, 2021
Priority date	May 22, 2019
Publication date	Mar 10, 2022
Grant date	—

Abstract

A laser sensor module includes a laser diode configured emit a laser beam, an electrical driver configured to supply the laser diode with a driving current to stimulate emission of the laser beam, a detector, and an optical arrangement configured to focus the laser beam to a focus region. The laser diode is arranged to emit the laser beam through the optical arrangement to the focus region. The optical arrangement comprises an emission window. The detector is arranged to determine an interference signal. The laser sensor module comprises a soiling detection unit configured to vary a wavelength of the laser beam with a variation amplitude over a predetermined time period to provide a soiling detection signal indicative of a soiling of the emission window based on an interference signal during the wavelength variation of the laser beam.

First claim

What is claimed is:

1 . A laser sensor module, comprising:
a laser diode configured emit a laser beam, an electrical driver configured to supply the laser diode with a driving current to stimulate emission of the laser beam, a detector, and an optical arrangement configured to focus the laser beam to a focus region, wherein the laser diode is arranged to emit the laser beam through the optical arrangement to the focus region, wherein the optical arrangement comprises an emission window, wherein the detector is arranged to determine an interference signal, wherein the laser sensor module comprises a soiling detection unit configured to vary a wavelength of the laser beam with a variation amplitude over a predetermined time period to provide a soiling detection signal indicative of a soiling of the emission window based on an interference signal during the wavelength variation of the laser beam, and wherein the variation amplitude and the predetermined time period are set to generate the soiling detection signal with a frequency in a range from 1 kHz to 100 MHz.

2 . The laser sensor module of claim 1 , wherein the wavelength variation is based on at least one of a driving current variation, a bias voltage variation, or a temperature variation.

3 . The laser sensor module of claim 1 , wherein a slope of the driving current variation is set such that at least three sine waves are present in the soiling detection signal.

4 . The laser sensor module of claim 1 , wherein the soiling detection unit is arranged to cause the electrical driver to provide a driving current to the laser diode which varies over the predetermined time period,
wherein an amplitude of the driving current variation is in a range from 0.05 mA to 2 mA.

5 . The laser sensor module of claim 1 , wherein the predetermined time period is in a range from 1 μs to 5 ms.

6 . The laser sensor module of claim 1 , wherein the soiling detection unit is arranged to cause the electrical driver to provide a driving current to the laser diode which varies with a linear slope over the predetermined time period.

7 . The laser sensor module of claim 1 , wherein the soiling detection unit is arranged to cause the electrical driver to provide a driving current to the laser diode which varies over the predetermined time period with a slope such that the wavelength of the laser beam varies linearly over the predetermined time period.

8 . The laser sensor module of claim 3 , wherein the slope is a single slope.

9 . The laser sensor module of claim 3 , wherein the soiling detection unit is arranged to cause the electrical driver to provide a driving current to the laser diode which varies over the predetermined time period according to a wave form.

10 . The laser sensor module of claim 1 , wherein the varying driving current in the predetermined time period is below the driving current provided to the laser diode in a measurement mode of the laser sensor module.

11 . The laser sensor module of claim 1 , further comprising a plurality of additional laser diodes, the laser diode and the plurality of additional laser diodes arranged to emit respective individual laser beams, wherein the soiling detection unit is configured to vary a wavelength of the laser beams to provide a soiling detection signal based on respective interference signals during the wavelength variation of the laser beams.

12 . The laser sensor module of claim 11 , wherein the optical arrangement is configured to direct the laser beams emitted by the first laser diode and the plurality of additional laser diodes such that the laser beams cross the emission window at substantially the same position.

13 . A device comprising the laser sensor module of claim 1 .

14 . A method of detecting a soiling of an emission window of a laser sensor module, the method comprising:
emitting a laser beam through an emission window, varying a wavelength of the laser beam over a predetermined time period, determining an interference signal based on the varying wavelength, and providing a soiling detection signal indicative of a soiling of the emission window based on the interference signal determined during variation of the wavelength.

15 . A computer program comprising processor executable program code that, when executed by a processor of a laser sensor device, is configured to cause a laser sensor device to carry out the method of claim 14 .

Assignees

• Trumpf Photonic Components Gmbh
• Bosch Gmbh Robert

Inventors

• Van Der Lee Alexander Marc
• Spruit Johannes Hendrikus Maria
• Ouweltjes Okke
• Weiss Robert

Classifications

• G01S7/497 Primary

  Means for monitoring or calibrating · CPC title

• G01S7/4815

  using multiple transmitters · CPC title

• G01S7/4808

  Evaluating distance, position or velocity data · CPC title

• G01S7/4916 Primary

  using self-mixing in the laser cavity · CPC title

• G01S7/4816

  of receivers alone · CPC title