Laser Diode Alignment via Passive Optical Feedback
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Solution Overview
Problem
Conventional methods for aligning laser diodes in laser projectors are inefficient and costly, particularly in compact form factors, due to the need for precise manual placement or complex automated machinery, and often result in human errors or high manufacturing costs.
Innovation Solution
A method involving an alignment beam and photodetector system that allows for the precise positioning and orientation of laser diodes without requiring electrical power, using a pick and place machine and robotic appendages to adjust the diodes until the alignment beam meets a threshold value, simplifying the alignment process and reducing the need for complex machinery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual placement of laser diodes is used, then alignment precision can be achieved, but manufacturing cost and time increase significantly
Solution Approach 1:
The patent replaces manual mechanical placement with an automated alignment system that uses optical feedback (alignment beam and photodetector) to guide the positioning of laser diodes. The system substitutes human-operated mechanical adjustment with an automated mechanism that uses light detection to achieve precise alignment without manual intervention.
2Manufacturing precision
If automated machinery is used to align laser diodes, then alignment precision improves, but device complexity and cost increase
Solution Approach 1:
The patent introduces an alignment beam and photodetector as intermediary elements that facilitate the alignment process. These intermediaries provide optical feedback to indicate whether the laser diode is properly aligned, enabling a simpler automated system to achieve high precision without complex machinery. The intermediary translates the alignment status into detectable optical signals.
3Manufacturing precision
If electrical power is provided to laser diodes during alignment, then alignment accuracy improves, but maintaining electrical connection becomes difficult
Solution Approach 1:
The patent performs preliminary positioning and alignment of the laser diode using the alignment beam and photodetector system before providing electrical power to the diode. This preliminary mechanical alignment ensures the diode is correctly positioned in terms of location and orientation, so that when power is subsequently applied, the diode is already aligned with the optical path, eliminating the need to maintain electrical connections during the alignment process.
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
This method enables efficient and cost-effective alignment of laser diodes, reducing manufacturing costs and improving the accuracy of laser projector assembly, especially in compact form factors like wearable heads-up displays.
Implementation Method 1
aiming an alignment beam produced by an alignment light source to pass through the first location at which the first laser diode is to be mounted
Implementation Method 2
positioning and orienting a photodetector with respect to the first location at which the first laser diode is to be mounted to detect any portion of the alignment beam that successfully passes through the first location
Data Source
AI summary
The present disclosure generally relates to methods of assembling projectors, and more particularly, to methods of aligning laser diodes in laser projectors. Implementations of the present disclosure include positioning an alignment beam and a photodetector in an optical path of the projector. The alignment beam propagates from an alignment light source through a location where a laser diode is to be mounted. A laser diode is then initially positioned in the optical path with a laser cavity of the diode acting as a passive waveguide during the assembly process. The laser diode is then fixed in place at a position and, or, an orientation that corresponds to light from the alignment beam passing through a laser cavity of the diode to be aligned and registering at least a minimum threshold value of a measure at the photodetector.