Patterned Laser Self-Mixing Sensing for Position and Velocity Detection

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Solution Overview

Problem

Conventional eye tracking systems require additional camera systems, making them costly and complex, and are not efficient in obtaining position and velocity information using self-mixing interference (SMI) measurements.

Innovation Solution

A laser sensor that emits a one- or two-dimensional patterned laser beam onto an object, allowing for self-mixing interference signal analysis to extract multiple frequencies indicative of distances and velocities along the patterned beam, eliminating the need for additional camera systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a camera system is added to obtain position and velocity information, then measurement capability is improved, but device complexity and cost increase

Engineering Contradiction:

Improveposition and velocity detection capabilityVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the camera system and laser sensor into a single integrated device. The laser sensor unit is positioned within the camera housing, and both sensors share common structural support and processing electronics, eliminating the need for separate mounting and reducing overall system complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The processing electronics serve dual functions by handling data from both the camera sensor and laser sensor. The same processor analyzes images from the camera and processes signals from the laser sensor to generate position and velocity information, making the electronic system multi-functional

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If a camera system is added to obtain position and velocity information, then measurement capability is improved, but cost increases

Engineering Contradiction:

Improveposition and velocity detection capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system uses the existing camera housing and processing electronics to support the laser sensor, rather than requiring dedicated separate components. The camera structure serves as the mounting framework, and the same processor handles both camera and laser data, making the system self-sufficient

Inventive Principle:

Principle #25Self-service

3Device complexity

If self-mixing interference measurements are used to obtain position and velocity information, then device complexity is reduced, but measurement precision is insufficient

Engineering Contradiction:

Improvesystem complexityVSAvoidposition and velocity detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the measurement function into two independent sensor systems: a camera for position information and a laser sensor for velocity information. Each sensor handles a specific measurement task, and the processing electronics integrate both data streams to provide comprehensive position and velocity detection with high precision

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The processing electronics act as an intermediary that receives and integrates data from both the camera sensor and laser sensor. It combines the position information from the camera with velocity information from the laser sensor to generate accurate trajectory and motion analysis

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The laser sensor provides accurate detection of position and velocity information with high spatial resolution and reduced complexity and cost, making it suitable for eye gaze angle detection and other applications.

Implementation Method 1

laser light reflected from the object re-enters the laser source and interferes with the optical wave within the laser resonator

Methodology Applied

Scientific EffectSelf-mixing interference: Interference

Implementation Method 2

laser light reflected from the object

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 3

intensity variations that are sensed by a detector, e.g. a photodiode

Methodology Applied

Scientific EffectPhotoelectric detection: Photoelectric Effect

Data Source

PatentUS12241741B2Laser sensor, system and method for self-mixing interferometry

Publication Date: 2025.03.04 ROBERT BOSCH GMBH

AI summary

A laser sensor includes a laser source configured to emit a laser beam, and optics configured to project the laser beam as a one- or two-dimensional patterned laser beam onto an object to be examined, such that a distance of the patterned laser beam from the laser source varies along the patterned laser beam projected on the object. The laser sensor further includes a detector configured to determine a self-mixing interference signal generated by laser light of the patterned laser beam reflected from the object back into the laser source, and circuitry configured to analyze a spectrum of the self-mixing interference signal and extract from the spectrum of the self-mixing interference signal multiple frequencies that are indicative of at least one of the following: multiple distances along the patterned laser beam from the laser source, or multiple velocities along the patterned laser beam with respect to the laser source.