VCSEL Illuminator Module With Reflected-Light Eye-Safety Control
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Solution Overview
Problem
High power miniature illuminators in portable computing devices, such as VCSELs, pose eye-safety hazards due to potential damage or contamination of optical components, which can lead to unsafe laser emission levels.
Innovation Solution
Incorporating multiple photodetectors and a controller within the illuminator module to monitor the distribution of reflected light, regulating the optical output power if an unsafe level is detected, including features like ambient light subtraction and temperature sensing to ensure eye-safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high power VCSEL illuminators are used to achieve efficient electro-optic conversion and small size, then productivity and device miniaturization are improved, but eye safety and reliability deteriorate due to potential optical component damage or contamination
Solution Approach 1:
The patent implements preliminary safety measures by placing optical components (diffusers, lenses) in the beam path before emission, and by incorporating monitoring photodetectors that continuously check for component integrity before unsafe emission occurs. The system proactively prevents eye safety hazards rather than reacting to them after occurrence.
Solution Approach 2:
The patent employs feedback mechanisms through monitoring photodetectors that detect the optical output and provide real-time information to a control circuit. When the monitored light distribution indicates potential safety hazards (such as component damage or contamination), the system automatically adjusts or shuts off the VCSEL output to maintain eye safety.
2Reliability
If optical components are added to modify beam properties for safe operation, then eye safety is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into integrated components. The monitoring photodetectors are integrated with the VCSEL array on the same substrate, and the control circuit is embedded within the illuminator module. This merging reduces overall device complexity while maintaining the safety functions provided by optical components.
Solution Approach 2:
The patent designs optical components to serve multiple functions. The diffuser both modifies the beam pattern for safe operation and serves as a reference for monitoring photodetectors to detect its own integrity. The monitoring system simultaneously checks for component damage, contamination, and unsafe emission levels, consolidating multiple safety checks into a unified system.
3Reliability
If monitoring systems are implemented to detect optical component failures, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent implements self-service monitoring where the system monitors its own operational status. The photodetectors are part of the illuminator module itself, and the control circuit is integrated within the same device. This self-monitoring capability enables the system to detect its own component failures and automatically respond without external monitoring equipment.
Solution Approach 2:
The patent uses photodetectors to create optical copies or representations of the light field for monitoring purposes. Instead of directly monitoring physical component integrity, the system detects light distribution patterns that indicate component status, using optical information as a proxy for physical state monitoring.
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
Enhances eye-safety by detecting and mitigating optical component failures, maintaining safe laser emission levels, and preventing potential hazards in both direct and indirect time-of-flight measurements.
Implementation Method 1
Multiple photodetectors are operable to detect light reflected by the optical component
Implementation Method 2
These devices can be pulsed with very fast rise times suitable for time-of-flight applications. They are small, but produce high power laser beams with efficient electro-optic conversion.
Implementation Method 3
An optical component is disposed over the light source and is operable to modify an optical characteristic of the light produced by the light source
Data Source
AI summary
Illuminator modules having improved safety features are described. In some implementations, light to be emitted from a module is produced by a light source, and light reflected by an optical component disposed over the light source is detected by a photodetectors. A distribution of the reflected light detected by the photodetectors is monitored, and an optical output power of the light source is regulated if it is determined, based on the monitored distribution of light, that an unsafe level of light may be emitted from the module.