Coherent Light Optical Sensor for Glass Surface Navigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional optical mice are bulky and costly due to complex packaging and illumination requirements, and they fail to function properly on glass-covered surfaces because the smooth top surface lacks sufficient structure for image measurement.
Innovation Solution
An optical pointing device using a coherent light source, such as a VCSEL, that emits light at normal incidence, creating a speckle pattern on the surface, which is detected by an array of photodetectors, allowing for displacement calculation without the need for intricate optics or lenses, and operates effectively even under glass covers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical mice use shallow angle illumination with LEDs and imaging lenses, then the device can sense surface structure, but the package size increases and manufacturing precision requirements increase
Solution Approach 1:
The patent replaces the traditional mechanical/optical system (LED + lens + image sensor) with a coherent light source that directly generates speckle patterns. This substitution eliminates the need for complex imaging optics and reduces packaging complexity while maintaining measurement precision through the speckle pattern analysis method
Solution Approach 2:
The patent changes the illumination parameter from incoherent LED light at shallow angles to coherent light at normal incidence. This parameter change transforms the illumination mechanism, enabling direct speckle pattern generation without complex optical systems, thereby reducing device complexity while preserving measurement capability
2Measurement precision
If traditional optical mice use imaging lenses and large foot prints, then the device can capture surface images, but the device footprint increases
Solution Approach 1:
The patent extracts and removes the imaging lens from the traditional optical mouse design. By using coherent light to directly generate speckle patterns on the surface, the system eliminates the need for lens-based image capture, thereby reducing the device footprint while maintaining measurement precision through alternative speckle analysis
3Measurement precision
If traditional optical mice illuminate at shallow angles, then the device can sense surface details, but the light source must be mounted at a distance increasing package size
Solution Approach 1:
The patent inverts the traditional illumination approach by using normal incidence illumination instead of shallow angle illumination. This inversion allows the light source to be positioned close to the surface while still generating adequate speckle patterns for measurement, thereby reducing the package size without sacrificing surface detail sensing capability
4Adaptability or versatility
If traditional optical mice are designed for opaque surfaces, then the device can function on standard surfaces, but the device fails on glass-covered surfaces
Solution Approach 1:
The patent introduces coherent light as an intermediary that can penetrate or reflect off glass surfaces to generate speckle patterns. This intermediary illumination method enables the device to function on glass-covered surfaces by creating measurable patterns regardless of the underlying surface type, thereby improving adaptability and reliability across different surface conditions
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 design reduces the size and cost of the device while enabling operation on glass-covered surfaces by utilizing a coherent light source to generate a speckle pattern that provides the necessary image structure for navigation, eliminating the need for complex optics and minimizing manufacturing precision requirements.
Implementation Method 1
The coherent light source emits coherent light in a cone of angles about an illumination direction
Implementation Method 2
creating a speckle pattern on the surface, which is detected by an array of photodetectors
Implementation Method 3
An image sensor in the mouse records an image of the illuminated surface periodically
Data Source
AI summary
An apparatus having a coherent light source, an optical sensor, and a controller that can be utilized in optical mice and the like is disclosed. The coherent light source emits coherent light in a cone of angles about an illumination direction. The optical sensor includes an array of photodetectors disposed on a die having a surface substantially perpendicular to the illumination direction. The controller compares first and second images recorded by the optical sensor at different times and determines a displacement indicative of the direction and distance the apparatus has moved between the two different times. A portion of the coherent light source is bonded to the die at a location within the array of photodetectors.