Laser Light Module Protection Circuit for Class 1 Eye Safety
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Solution Overview
Problem
Existing laser modules, particularly those used for 3D imaging, face challenges in maintaining eye-safe operation compliant with laser safety class 1 due to potential overexposure from malfunctioning electronic elements and mechanical instability of diffractive optical elements, which can lead to increased laser output power beyond safety limits.
Innovation Solution
A light module with an electronic circuit that includes a current source for continuous wave operation and a protection controller to interrupt the current in case of failure, along with a temperature control mechanism to prevent overheating, ensuring safe operation without additional photo diodes or electrically conducting materials on diffractive optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electronic element is used for regulating current through the laser diode, then the device complexity is reduced, but the reliability of maintaining laser safety class 1 compliance deteriorates due to potential malfunction
Solution Approach 1:
The patent implements a protection controller that proactively monitors the operational status of the current source and preemptively interrupts the driving current when a malfunction is detected. This prior cushioning mechanism prevents potential safety violations before they occur, ensuring laser safety class 1 compliance even when using a simplified single-element current regulation design.
2Device complexity
If no additional photo diode and circuit are employed, then the device complexity is reduced, but the ability to detect and respond to laser radiation power deviations deteriorates
Solution Approach 1:
The patent introduces an intermediary protection controller that indirectly monitors laser safety compliance by detecting malfunctions in the current source. Instead of directly measuring laser radiation power with additional photo diodes, the controller acts as an intermediary that infers potential safety issues from electrical parameter deviations, thereby maintaining safety without adding complex optical monitoring hardware.
3Ease of manufacture
If the diffractive optical element is made from polymeric material, then the ease of manufacture is improved, but the mechanical stability and heat resilience deteriorate leading to element breakage or deformation
Solution Approach 1:
The protection controller provides beforehand cushioning by monitoring operational conditions that could lead to diffractive optical element failure. While the polymeric element remains susceptible to mechanical and thermal damage, the control system preemptively responds to conditions that might cause element failure, preventing catastrophic loss of the diffractive structure and maintaining laser safety.
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 maintains laser output within safe limits by interrupting the current and controlling temperature, preventing overexposure and ensuring compliance with laser safety class 1 without increasing module size or complexity, suitable for mobile applications.
Implementation Method 1
a laser diode which is designated for generating laser radiation. The laser diode as used herein is, in general, an edge emitting laser diode which comprises a semiconducting wafer having a surface and two cleaved edges, wherein the laser radiation being generated by applying a driving electrical current to the wafer
Implementation Method 2
the laser module can, further, comprise a diffractive optical element in a beam path after the laser radiation has left the laser diode
Implementation Method 3
an additional photo diode having an additional circuit can be employed, wherein the additional photo diode may be designed for receiving a partition of the emitted laser radiation, and wherein the additional circuit may be designated, on one hand, for determining the power of the emitted laser radiation
Data Source
Figure 1~2
AI summary
A light module and a method for its operation Abstract The present invention refers to a light module (110) and a method for operating the light module (110). The light module (110) comprises - a light source (112); - an electronic circuit (124) for driving the light source (112); wherein the electronic circuit (124) comprises ○ a current source (126), wherein the current source (126) is designated for generating and controlling a control current for driving the light source (112), and ○ a protection controller (136), wherein the protection controller (136) is designated for interrupting the control current to the light source (112) in an event in which the current source (126) fails. The light module (110) and the related method address an eye-safe operation of the light module (110), specifically for a laser light source comprised by the light module (110) to achieve compliance to laser safety class 1.