VCSEL Illuminator Package With Optical Interlock for Eye Safety
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Solution Overview
Problem
Ensuring high power laser illuminators in mobile devices meet laser safety regulations, particularly in situations where the device is damaged or serviced, and preventing unsafe levels of illumination.
Innovation Solution
Incorporating an optical element in the VCSEL illuminator package that modifies the output beam and an optical detector to sense changes in radiation intensity, with a control circuit turning off the VCSEL drive current in response to predetermined intensity changes or threshold violations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power VCSEL devices are used to deliver high power laser beams with efficient electro-optic conversion, then the illuminator can provide sufficient illumination for 3D imaging and time of flight measurements, but the laser beam may exceed eye-safe levels and violate laser safety regulations
Solution Approach 1:
A beam modifying optical element is introduced as an intermediary component between the VCSEL and the external environment. This optical element modifies the laser beam characteristics (such as diverging the beam or reducing intensity) to ensure the illuminator operates within eye-safe power levels while maintaining sufficient illumination capability for 3D imaging applications
Solution Approach 2:
An optical detector is implemented to monitor the laser beam power output, and this detection signal is fed back to a control circuit that adjusts the VCSEL drive current. This closed-loop feedback system automatically maintains the laser output within eye-safe levels, preventing harmful radiation while allowing high power operation when safe
2Ease of manufacture
If the VCSEL illuminator is designed for high volume low cost manufacture and low cost assembly into mobile devices, then the illuminator can be mass-produced for consumer electronics, but additional safety components and control circuits increase device complexity and manufacturing cost
Solution Approach 1:
The optical detector serves multiple functions: it monitors beam power for eye safety, detects optical element status (presence/alignment), and provides feedback for power control. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity while maintaining comprehensive safety and manufacturing efficiency
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
Provides electrical interlock signals to ensure eye-safe operation by immediately turning off the VCSEL in case of damage or dislodgment of optical components, maintaining safety standards.
Implementation Method 1
an optical detector arranged to receive and sense VCSEL radiation reflected or backscattered from the optical element
Implementation Method 2
They are small but produce high power laser beams with efficient electro-optic conversion
Data Source
Figure 1A~1D
Figure 2
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AI summary
A miniature illuminator is described which is suitable for assembly into mobile electronics devices such as cell phones and computer tablets. Features of the invention overcome the complexity of current miniature illuminators by using single molded structure which includes all the electrical feedthrough connections and has the features necessary for accurate mounting of optical components. The molded structure includes laser safety connections which provide an electrical interrupt signal when the illuminator is damaged in a way that could result in propagation of non-eye safe illuminator beams. In an alternate operation the illuminator provides a signal when a subject gets too close to the illuminator and would receive unsafe VCSEL illuminator beam. The laser safety feature is integrated into the molded Illuminator package so that separate electrically connected structures to achieve this function are eliminated