VCSEL Light Source with Integrated Monitor Elements for Speckle Noise Reduction
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Solution Overview
Problem
Laser light sources with speckle noise due to coherence issues affect image quality and measurement accuracy, as existing methods like VCSELs face challenges with manufacturing errors, wavelength differences, and self-heating, leading to unstable output and varying average brightness among light sources.
Innovation Solution
A vertical cavity surface emitting laser (VCSEL) design with multiple light-emitting elements and corresponding monitor elements on the same substrate, enabling real-time feedback control to stabilize output and reduce speckle noise by ensuring uniform average brightness across combined speckle patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple light sources are used to reduce speckle noise, then speckle noise is reduced, but uniformity of average brightness deteriorates due to manufacturing errors and characteristic drift
Solution Approach 1:
The patent implements feedback control by using detecting elements to monitor the output light quantity of each light-emitting element and adjusting the drive current accordingly. This ensures that each light source outputs light with uniform average brightness, maintaining the speckle reduction effect while eliminating brightness non-uniformity caused by manufacturing errors and characteristic drift.
Solution Approach 2:
The patent changes the drive current parameter for each light-emitting element based on detected output characteristics. By individually adjusting the drive current of each light source, the system compensates for manufacturing variations and thermal drift, ensuring uniform average brightness across all light sources while maintaining multiple light sources for speckle reduction.
2Object-affected harmful factors
If multiple light sources are used to reduce speckle noise, then speckle noise is reduced, but device complexity increases
Solution Approach 1:
The patent merges the light-emitting function and detection function into a single integrated chip. Multiple light-emitting elements and detecting elements are fabricated on the same substrate, allowing compact integration and simplified system structure while maintaining multiple light sources for speckle reduction.
Solution Approach 2:
The detecting elements serve dual purposes: monitoring the output light quantity for feedback control and potentially serving as additional light sources when needed. This multi-functionality reduces the need for separate detection components, simplifying the overall device structure while enabling speckle reduction through multiple light sources.
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 effectively reduces speckle noise by stabilizing the output of light sources, improving image quality and measurement accuracy by achieving a consistent average brightness across combined speckle patterns, thereby enhancing the noise reduction effect.
Implementation Method 1
a plurality of detecting elements individually detect quantities of output light of the light-emitting elements
Implementation Method 2
Laser light have characteristic property such as coherence that causes flickering or noise in a spotted pattern called speckles on an observed face due to diffraction of scattering light
Implementation Method 3
speckles on an observed face due to diffraction of scattering light on an irradiated surface
Data Source
AI summary
According to one embodiment, a light source includes a plurality of light-emitting elements each including one or more surface-emitting lasers; and a plurality of detecting elements located on a same substrate as the light-emitting elements. The detecting elements individually detect quantities of output light of the light-emitting elements.