Tilted Diode-Laser Stack Aberration Compensation
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Solution Overview
Problem
Diode-laser stacks face limitations in power scaling due to spherical aberration in single-element lenses, which degrades focusing and increases costs with corrective phase-plates or large aspheric lenses.
Innovation Solution
The solution involves tilting the substantially-collimated beams from diode-laser bars with respect to the optical axis to compensate for spherical aberration in a plano-convex focusing lens, allowing all beams to converge to a common focus location, using either displaced fast-axis collimating lenses or tilted diode-laser bar assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-element lens is used to focus optical output from diode-laser stack, then device complexity is reduced and cost is decreased, but spherical aberration degrades focusing quality and limits power scaling
Solution Approach 1:
The patent changes the orientation parameter of individual diode-laser bars within the stack, tilting them at specific angles relative to the optical axis. This parameter change compensates for spherical aberration in the single-element lens, allowing all beams to converge to a common focus location and maintaining high focusing quality without complex corrective optics
Solution Approach 2:
The patent introduces asymmetric positioning of diode-laser bars within the stack, where bars are tilted at different angles depending on their position. This asymmetric arrangement compensates for the symmetric spherical aberration of the lens, enabling all beams to focus to a single point while using a simple, low-cost single-element lens
2Quantity of substance
If large-diameter lens is used to capture all light from diode-laser stack, then optical power capture is improved, but spherical aberration increases and limits power scaling
Solution Approach 1:
By changing the tilt angle parameter of individual diode-laser bars based on their position in the stack, the system enables a large-diameter single-element lens to focus all captured optical power to a common location, compensating for the increased spherical aberration that would normally limit power scaling
3Manufacturing precision
If corrective phase-plates or large aspheric lenses are used to overcome spherical aberration, then focusing quality is improved, but cost increases significantly
Solution Approach 1:
The patent changes the spatial orientation parameters of the diode-laser bars themselves rather than modifying the focusing lens. This approach achieves aberration correction through simple mechanical tilting of laser bars, avoiding the need for expensive aspheric lenses or customized phase-plates while maintaining high focusing quality
Solution Approach 2:
Instead of correcting aberration in the focusing lens (the traditional approach), the patent inverts the problem by introducing controlled angular deviations at the source (diode-laser bars). This reverse approach achieves the same aberration compensation effect but with much lower cost and simpler manufacturing
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 approach enables efficient and cost-effective tight focusing of optical output from diode-laser stacks, ensuring that a significant portion of optical power is delivered to the application without the need for expensive corrective optics.
Implementation Method 1
A focusing lens is provided having an optical axis and spherical aberration. The focusing lens intercepts the substantially-collimated beams of all of the diode-laser bars. The stacked diode-laser bars and the focusing lens are arranged to bring all of the substantially-collimated beams to focus on the optical axis.
Implementation Method 2
The optical beam from an individual diode-laser emitter is divergent in a slow-axis direction and highly-divergent in an orthogonal fast-axis direction. Typically, the optical beams of all the emitters along a diode-laser bar are collimated in the fast-axis direction by a single high-power cylindrical lens, called a 'fast-axis collimating lens'.
Data Source
AI summary
Optical output beams from a vertical stack of diode-laser bars are focused by a simple focusing lens on an optical axis of the lens. The optical output beams from outlying diode-laser bars in the vertical stack are tilted with respect to the optical axis of the focusing lens such that optical output from the whole vertical stack is brought to a common focus location on the optical axis of the focusing lens.