VCSEL Light Barrier Structure for Eye-Tracking Noise Suppression
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Solution Overview
Problem
Vertical cavity surface-emitting lasers (VCSELs) used in eye-tracking systems face challenges due to spontaneous emissions that increase noise and reduce detection accuracy, particularly when positioned close to photosensors.
Innovation Solution
A light source structure incorporating a VCSEL with a light barrier that blocks spontaneous emissions, allowing for directed emission through the top surface while minimizing noise interference with the photodetector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If VCSEL and photosensor are positioned in close proximity, then device size is reduced, but spontaneous emission received by photosensor increases noise
Solution Approach 1:
A light barrier structure is introduced as an intermediary element between the VCSEL and photodetector. The light barrier selectively blocks spontaneous emission from reaching the photodetector while allowing the directed laser emission to pass through to the target and reflect back to the photodetector. This mediator resolves the contradiction by enabling close proximity positioning without the noise penalty.
Solution Approach 2:
The light barrier is positioned specifically around the VCSEL device to provide localized suppression of spontaneous emission. Rather than requiring the entire system to be separated, the light barrier creates a localized control zone around the VCSEL that blocks noise in specific directions while maintaining the overall compact structure.
2Measurement precision
If light barrier is added to block spontaneous emission, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The light barrier structure is merged with the VCSEL device packaging and mounting structure. Rather than being a separate complex component, the light barrier is integrated into the existing structural elements, such as the VCSEL mount or housing, thereby providing noise suppression without proportionally increasing device complexity.
Solution Approach 2:
The light barrier structure serves multiple functions: it blocks spontaneous emission from reaching the photodetector, provides mechanical support for the VCSEL, and can be integrated with thermal management structures. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
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 solution enables a compact VCSEL-photodetector combination with reduced spontaneous emission, enhancing detection accuracy in eye-tracking systems without increasing device size.
Implementation Method 1
vertical cavity surface-emitting laser (VCSEL) device... configurable to output directed emission of light through the top surface
Implementation Method 2
VCSELs tend to also produce spontaneous emissions in other directions. The spontaneous emission received by the photosensor increases noise
Implementation Method 3
light barrier configured to receive spontaneous emission out of the VCSEL device
Data Source
AI summary
A light source structure includes a vertical cavity surface-emitting laser (VCSEL) device having a top surface and at least one side surface substantially perpendicular to and adjoining the top surface. The VCSEL device is configurable to output directed emission of light through the top surface. The light source structure also includes a light barrier surrounding at least a top portion of the VCSEL device and separated from the at least one side surface. The light barrier is configured to receive spontaneous emission out of the VCSEL device through the at least one side surface.