Illumination System Safety Interlock Using Resistivity Monitoring
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Solution Overview
Problem
High-powered illumination devices, such as lasers, used in 3-D sensing systems pose safety hazards due to potential malfunctions or structural damage, which can cause eye damage if not properly monitored.
Innovation Solution
An illumination system with a transparent conductive material layer on an optical element, monitored by an interlock circuit that measures resistivity and controls the illumination device based on safety criteria, including synchronization with the modulation frequency, to prevent unsafe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-powered illumination devices are used for 3-D sensing, then sensing capability is improved, but eye safety is compromised
Solution Approach 1:
The patent applies preliminary action by placing a transparent conductive material layer on the optical element before operation, which serves as a pre-configured safety mechanism. This layer is designed to absorb specific wavelengths of light and generate a measurable resistivity signal that indicates whether the illumination device is operating safely, preventing eye damage before it can occur.
Solution Approach 2:
The patent implements feedback through an interlock circuit that continuously monitors the resistivity of the transparent conductive material layer. The circuit measures the resistivity signal generated by light absorption and provides real-time feedback to control whether the illumination device operates or shuts down, ensuring safety while maintaining sensing capability.
2Reliability
If a transparent conductive material layer is added to the optical element, then safety monitoring is enabled, but optical performance may be degraded
Solution Approach 1:
The patent applies local quality by designing the transparent conductive material layer to have specific localized properties: it is transparent to most wavelengths of light to maintain optical performance, but has controlled absorption at specific wavelengths to generate the resistivity signal for safety monitoring. This selective property distribution allows simultaneous achievement of safety monitoring and optical transmission.
3Measurement precision
If resistivity measurement is performed synchronously with modulation frequency, then measurement precision is improved, but system complexity increases
Solution Approach 1:
The patent applies periodic action by synchronizing the resistivity measurement with the modulation frequency of the illumination device. The interlock circuit performs resistivity measurements at regular intervals matched to the modulation period, which enhances measurement precision by capturing signals at optimal phases while using the existing modulation rhythm to simplify control logic.
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 mitigates the risk of eye damage by shutting off the illumination device when malfunctions or structural issues are detected, ensuring safe operation while being robust to noise and having minimal optical impact.
Implementation Method 1
The layer of transparent material comprises a material having a non-zero absorption at a wavelength of the light from the illumination device
Implementation Method 2
an interlock circuit configured to measure a resistivity of the layer of transparent material and to control operation of the illumination device based on the measured resistivity
Implementation Method 3
The interlock circuit is configured to measure the resistivity of the layer of transparent material synchronously with a modulation frequency of the illumination device. The interlock circuit is configured to implement lock-in demodulation.
Data Source
AI summary
An illumination system (200) includes an illumination device (202); an optical element (206) positioned to receive light (208) from the illumination device (202); a layer (210) of a transparent material disposed on the optical element (206) and positioned to receive light (208) from the illumination device (202); and an interlock circuit (220) configured to measure a resistivity of the layer (210) of transparent material and to control operation of the illumination device (202) based on the measured resistivity.