Optical Navigation Using Scattered Light for Glass Surfaces
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Solution Overview
Problem
Conventional optical navigation systems struggle to produce high contrast and large field of view images on surfaces like glass tables, which limits their ability to accurately track movements, especially when the surface lacks structure directly under the field of view.
Innovation Solution
The system emits an illumination beam at a nonzero angle of incidence to produce both specular and scattered light, with the image sensor receiving the scattered light at an offset angle, allowing for high contrast and large field of view images to be captured in a minimized volume, suitable for various surfaces including glass tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional optical navigation systems use normal illumination to capture images, then the system can operate on structured surfaces, but the field of view is limited and the system volume increases
Solution Approach 1:
The patent changes the illumination geometry from normal incidence to oblique incidence, introducing a dimensional change in the optical path. This allows the system to achieve a larger field of view without increasing the system volume by utilizing scattered light at angles rather than direct reflected light
2Adaptability or versatility
If conventional optical navigation systems illuminate surfaces at normal incidence, then the system structure is simple, but glass tables and smooth surfaces produce low contrast images
Solution Approach 1:
The patent changes the illumination angle parameter from normal incidence to oblique incidence. This parameter change enables the system to generate sufficient scattered light for high contrast images on smooth surfaces like glass tables, while maintaining compatibility with structured surfaces
3Measurement precision
If the image sensor receives specular reflected light, then the optical path is direct and simple, but the navigation system cannot accurately track movements on smooth surfaces
Solution Approach 1:
The patent extracts the scattered light component from the total reflected light by using oblique illumination and positioning the image sensor to receive only scattered light at a predetermined angle. This separates the useful scattered light signal from the specular reflected light, enabling accurate movement tracking on smooth surfaces
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
This configuration enables accurate tracking of movements over a wide range of surfaces by minimizing system volume while maintaining high contrast and large field of view, even on smooth surfaces like glass tables, reducing noise and enhancing velocity measurement capabilities.
Implementation Method 1
The light source is positioned to emit an illumination beam of light along a first optical axis onto a target surface to produce a specularly reflected beam of light along a second optical axis and scattered light
Data Source
AI summary
A system and method for performing optical navigation uses scattered light to produce frames of image data to estimate displacement with respect to a target surface. The scattered light is produced from an illumination beam of light emitted along a first optical axis onto the target surface. The illumination beam of light also produces a specularly reflected beam of light along a second optical axis. The scattered light about a third optical axis, which is offset by a predefined angle with respect to the second optical axis, is received at an image sensor array to produce the frames of image.