Optical crosstalk calibration for ranging systems

Patent metadata

Field	Value
Publication number	US-11143750-B2
Application number	US-201615769868-A
Country	US
Kind code	B2
Filing date	Oct 24, 2016
Priority date	Oct 22, 2015
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

The present disclosure describes calibration methods for optoelectronic modules with active illumination, such as 3D ranging systems. Calibration methods include determining cross-talk calibration parameters for an optoelectronic module having an emitting channel and a receiving channel where the optoelectronic module is operable to demodulate modulated light incident on the receiving channel. Cross-talk calibration parameters are saved to a readable storage medium and recalled during distance measurements to an object or objects in a scene.

First claim

What is claimed is:

1. A calibration method, the method comprising:
determining cross-talk calibration parameters for an optoelectronic module having an emitting channel and a receiving channel, the optoelectronic module being operable to demodulate modulated light incident on the receiving channel, wherein said determining comprises:
directing modulated light from the emitting channel;
sampling cross-talk-target signals generated in the receiving channel, wherein the cross-talk-target signals correspond to incident modulated light due to cross-talk between the emitting channel and the receiving channel, and wherein sampling cross-talk-target signals includes performing optical power measurements of the incident modulated light
deriving the cross-talk calibration parameters from the cross-talk-target signals, wherein the cross-talk calibration parameters comprise one or more of: an amplitude of the cross-talk-target signal, a phase of the cross-talk-target signal, and/or a cross-talk-target signal offset, wherein the cross-talk-target signal offset corresponds to a total intensity of the cross-talk-target signal; and
storing the cross-talk calibration parameters on a readable storage medium.

2. The calibration method of claim 1 , wherein
directing modulated light from the emitting channel comprises directing modulated light from the emitting channel to a substantially absorbing target, the substantially absorbing target having a reflectivity of 5% or less.

3. The calibration method as in claim 2 , further comprising conveying instructions to a user of the optoelectronic module via software operable to receive the cross-talk calibration parameters from the readable storage medium, and operable to prompt the user to direct modulated light from the emitting channel to the substantially absorbing target.

4. The calibration method of claim 1 , wherein determining the cross-talk calibration parameters further includes:
covering the receiving channel.

5. The calibration method of claim 1 , the method further comprising:
directing modulated light from the emitting channel to an object;
sampling object signals generated in the receiving channel, wherein the object signals correspond to incident modulated light due to cross-talk between the emitting channel and receiving channel and due to modulated light reflected from the object, and wherein sampling object signals includes performing optical power measurements of the incident modulated light;
deriving measured object distance parameters from the object signals, wherein the measured object distance parameters comprise one or more of: an amplitude of the object signal, a phase of the object signal, and/or an object signal offset, wherein the object signal offset corresponds to a total intensity of the object signal; and
storing the measured object distance parameters on the readable storage medium.

6. The calibration method of claim 5 , wherein the cross-talk calibration parameters include the phase and the amplitude of the cross-talk-target signal, and wherein the object distance parameters include the phase and the amplitude of the object signal, the method further comprising:
receiving the cross-talk calibration parameters from the readable storage medium;
constructing a cross-talk calibration phasor having a phase corresponding to the phase of the cross-talk-target signal and an amplitude corresponding to the amplitude of the cross-talk-target signal;
constructing an object distance phasor having a phase corresponding to the phase of the object signal and an amplitude corresponding to the amplitude of the object signal; and
subtracting the cross-talk calibration phasor from the object distance phasor.

7. The calibration method as in claim 5 , further comprising conveying instructions to a user of the optoelectronic module via software operable to receive the cross-talk calibration parameters and object distance from the readable storage medium, and operable to prompt the user to direct modulated light from the emitting channel to the object.

8. The calibration method of claim 1 , the method further comprising:
determining offset parameters by directing modulated light from the emitting channel to a first partially absorbing target, the first partially absorbing target having a reflectivity of at least 90% at a first distance; wherein determining offset parameters further comprises:
sampling offset-target signals generated in the receiving channel, wherein the offset-target signals correspond to incident modulated light due to cross-talk between the emitting channel and the receiving channel and due to modulated light reflected from the first partially absorbing target at the first distance, and wherein sampling offset-target signals includes performing optical power measurements of the incident modulated light; and
deriving the offset parameters from the offset-target signals and the cross-talk calibration parameters, wherein the offset parameters comprise one or more of: an amplitude of the offset-target signal, a phase of the offset-target signal, and/or an offset-target signal offset, wherein the offset-target signal offset corresponds to a total intensity of the offset-target signal; and
wherein the method further comprises storing the offset parameters on the readable storage medium.

9. The calibration method of claim 8 , the method further comprising:
determining gain parameters by directing modulated light from the emitting channel to a second partially absorbing target, the second partially absorbing target having a reflectivity of at least 50%, at the first distance; wherein determining gain parameters further comprises:
sampling gain-target signals generated in the receiving channel, wherein the gain-target signals correspond to incident modulated light due to cross-talk between the emitting channel and the receiving channel and due to modulated light reflected from the second partially absorbing target at the first distance, and wherein sampling gain-target signals includes performing optical power measurements of the incident modulated light; and
deriving the gain parameters from the gain-target signals, the offset-target signals, and the cross-talk calibration parameters, wherein the gain parameters comprise one or more of: an amplitude of the gain-target signal, a phase of the gain-target signal, and/or a gain-target signal offset, wherein the gain-target signal offset corresponds to a total intensity of the gain-target signal; and
wherein the method further comprises storing the gain parameters on the readable storage medium.

10. The calibration method as in claim 9 , in which the method further includes deriving a linear fit calibration from the offset parameters and gain parameters, the linear fit calibration comprising a slope and an intercept of a linear fit, wherein the gain parameters delineate the slope of the linear fit, and the offset parameters delineate the intercept of the linear fit.

11. The calibration method as in claim 9 , further comprising conveying instructions to a user of the optoelectronic module via software operable to receive the cross-talk calibration parameters, the offset parameters, and the gain parameters from the readable storage medium; and operable to prompt the user to direct modulated light from the emitting channel to the second partially absorbing target.

12. The calibration method of claim 8 , the method further comprising:
determining gain parameters by directing modulated light from the emitting channel to the first partially absorbing target at a second distance; wherein determining gain parameters further comprises:
sampling gain-target signals genera

Assignees

• Ams Sensors Singapore Pte Ltd

Inventors

• Vaello Paños Miguel Bruno
• Sánchez Javier Miguel
• Strässle Cassian
• Chen Liming

Classifications

• G01C3/08 Primary

  Use of electric radiation detectors · CPC title

• G01S17/08

  for measuring distance only (indirect measurement G01S17/46; active triangulation systems G01S17/48) · CPC title

• G01S7/497 Primary

  Means for monitoring or calibrating · CPC title

• G01C25/00

  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 title