Lidar Laser Safety Control via Dynamic Power Adjustment
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Solution Overview
Problem
Lidar systems face challenges in automatically adjusting optical power to prevent excessive exposure, particularly when scanning rates deviate or when a person is detected within the field of view, which can lead to safety hazards.
Innovation Solution
A lidar system that dynamically adjusts the optical power of its probe beam based on scan-rate measurements and detection of individuals using an electronic controller, incorporating photodiodes and a camera to monitor and respond to scan rates and presence, ensuring compliance with safety standards like ANSI Z136.1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical power is increased to improve measurement precision and imaging quality, then the measurement precision is improved, but the laser safety hazard increases when scan rate deviates or person is detected
Solution Approach 1:
The patent implements dynamic optical power adjustment where the laser power is continuously adapted based on real-time scan rate monitoring and person detection status. The controller dynamically modifies the optical power level to maintain measurement precision when safe, and reduces power when safety hazards are detected, resolving the contradiction between precision and safety.
Solution Approach 2:
The system employs feedback mechanisms through photodiodes that continuously monitor the scan rate and provide real-time information to the controller. This feedback loop enables the system to automatically adjust optical power based on actual operating conditions, ensuring measurement precision is maintained while preventing excessive laser exposure when scan rate deviations or person presence are detected.
2Reliability
If the optical power is dynamically adjusted to ensure laser safety, then the laser safety is improved, but the measurement precision and imaging quality may deteriorate
Solution Approach 1:
The patent applies local quality by adjusting optical power specifically in response to local conditions such as person detection or scan rate deviations, rather than uniformly reducing power. When no hazards are present, full power is maintained for optimal measurement precision. This localized adjustment ensures safety compliance while preserving imaging quality in safe operating conditions.
3Productivity
If the scan rate is increased to improve productivity and scanning speed, then the productivity is improved, but the laser safety hazard increases due to reduced dwell time and potential stalling
Solution Approach 1:
The photodiode-based scan rate monitoring system provides continuous feedback to the controller, enabling real-time detection of scan rate deviations and mirror stalling conditions. This feedback mechanism allows the system to maintain high productivity through increased scan rates while automatically reducing optical power when stalling or unsafe conditions are detected, preventing excessive laser exposure.
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 system effectively prevents excessive exposure by dynamically adjusting optical power, ensuring safety and optimizing performance by maintaining compliance with maximum permissible exposure limits and enhancing safety protocols.
Implementation Method 1
an optical monitor configured to generate a stream of measurements of a scan rate of the optical-probe beam by optically sensing motion of the movable mirror
Implementation Method 2
the scan rate may continuously be monitored using suitably positioned photodiodes, a position-sensing photodetector, or a two-dimensional, pixelated light sensor configured to receive light reflected from the scanning mirror
Data Source
AI summary
A lidar system capable of automatically adjusting the optical power of an optical-probe beam thereof based on scan-rate measurements and/or detection of a person within the system's field of view. In an example embodiment, the automatic power-adjustment capability includes a capability of turning OFF the corresponding laser source, e.g., when the scanning mirror has stalled. In various embodiments, the scan rate may continuously be monitored using suitably positioned photodiodes, a position-sensing photodetector, or a two-dimensional, pixelated light sensor configured to receive light reflected from the scanning mirror. Depending on the specific embodiment, the reflected light may include a small portion of the optical-probe-beam light or may be generated using a separate dedicated light source.