Optical distance measuring device with calibration device

• US 8,891,068 B2
• Filed: 09/20/2010
• Issued: 11/18/2014
• Est. Priority Date: 10/05/2009
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Eisele, Andreas, Wolst, Oliver, Schmidtke, Bernd
• Primary Examiner(s): Geisel, Kara E
• Assistant Examiner(s): BOLOGNA, DOMINIC JOSEPH
• Application Number:
  US13/498,553
• Publication Number:
  US 20120236290A1
• Time in Patent Office: 1,520 Days
• Field of Search: 356 3- 22, 702/97
• US Class Current: 356/6
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• CPC Class Codes: G01S 17/32 using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

A measuring apparatus for optically measuring a distance to a target object is described. The measuring apparatus has a transmitting device for emitting periodically modulated optical measuring radiation towards the target object, a receiving device for detecting optical measuring radiation which returns from the target object, and an evaluation device for receiving and evaluating detection signals from the receiving device. The measuring apparatus also has a calibration device for calibrating the measuring apparatus, wherein the calibration device is designed to calibrate the measuring apparatus on the basis of detection of uncorrelated radiation which does not correlate with the modulated measuring radiation emitted by the transmitting device. In this case, the uncorrelated radiation may be in the form of background radiation. Alternatively, uncorrelated measuring radiation can be emitted by the transmitting device and can be detected by the receiving device.

Claims

1. A measuring device for optical distance measurement, in particular a handheld measuring device, comprising:

a transmitting unit for emitting periodically modulated optical measurement radiation toward a target object;

a receiving unit for detecting optical measurement radiation returning from the target object;

an evaluation unit for receiving and evaluating detection signals of the receiving unit; and

a calibration unit for calibrating the measuring device,

wherein the calibration unit is designed to calibrate the evaluation unit on the basis of a detection of uncorrelated radiation which does not correlate with the modulated measurement radiation emitted by the transmitting unit,

wherein a period of the periodically modulated measurement radiation is subdivided into a plurality of subperiods,

wherein the evaluation unit is designed to cumulate a detection signal received by the receiving unit over predetermined subperiods, and

wherein the calibration unit is designed to calibrate a length of the subperiods on the basis of a detection of unmodulated radiation.

2. The measuring device as claimed in claim 1 wherein the calibration unit is designed to calibrate the evaluation unit on the basis of a detection of unmodulated radiation.

3. The measuring device as claimed in claim 1, wherein the calibration unit is designed to calibrate the evaluation unit on the basis of a detection of background radiation.

4. The measuring device as claimed in claim 1, wherein the measuring device is designed to the effect that uncorrelated radiation impinges on the receiving unit with an intensity adapted to a detection sensitivity of the receiving unit.

5. The measuring device as claimed in claim 4, wherein:

the receiving unit has a paralyzable radiation detector, and

the unmodulated radiation is guided onto the receiving unit with an intensity adapted to a maximum of a detector signal, in particular a maximum detection event rate of the paralyzable radiation detector.

6. The measuring device as claimed in claim 1, wherein the receiving unit has at least one SPAD.

7. The measuring device as claimed in claim 1, wherein the measuring device is designed to determine a duration of a calibration process to be performed by the calibration unit on the basis of a predefined calibration accuracy and an intensity of the unmodulated radiation detected by the receiving unit.

8. A measuring device for optical distance measurement, in particular a handheld measuring device, comprising:

a transmitting unit for emitting periodically modulated optical measurement radiation toward a target object;

a receiving unit for detecting optical measurement radiation returning from the target object;

an evaluation unit for receiving and evaluating detection signals of the receiving unit; and

a calibration unit for calibrating the measuring device,

wherein the calibration unit is designed to calibrate the evaluation unit on the basis of a detection of uncorrelated radiation which does not correlate with the modulated measurement radiation emitted by the transmitting unit,

wherein the calibration unit is furthermore designed for emitting uncorrelated measurement radiation, and

wherein the calibration unit is designed to calibrate the evaluation unit on the basis of a detection of uncorrelated measurement radiation.

9. The measuring device as claimed in claim 8, wherein the measuring device is designed to guide measurement radiation, in particular uncorrelated measurement radiation, within the measuring device onto the receiving unit.

10. The measuring device as claimed in claim 8, wherein:

a period of the periodically modulated measurement radiation is subdivided into a plurality of subperiods;

the evaluation unit is designed to cumulate a detection signal received by the receiving unit over predetermined subperiods; and

the calibration unit is designed to calibrate a length of the subperiods on the basis of a detection of unmodulated radiation.

11. The measuring device as claimed in claim 8, wherein the measuring device is designed to the effect that uncorrelated radiation impinges on the receiving unit with an intensity adapted to a detection sensitivity of the receiving unit.

12. The measuring device as claimed in claim 11, wherein:

the receiving unit has a paralyzable radiation detector, and

the unmodulated radiation is guided onto the receiving unit with an intensity adapted to a maximum detection event rate of the paralyzable radiation detector.

13. The measuring device as claimed in claim 8, wherein the receiving unit has at least one SPAD.

14. The measuring device as claimed in claim 8, wherein the measuring device is designed to determine a duration of a calibration process to be performed by the calibration unit on the basis of a predefined calibration accuracy and an intensity of the unmodulated radiation detected by the receiving unit.