Laser Diode Assembly Bypass Control for Beam Homogeneity
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Solution Overview
Problem
High-power laser diode arrangements face challenges in achieving beam homogeneity due to production tolerances and aging differences among individual laser bars, requiring complex and costly optical corrections.
Innovation Solution
A bypass is connected to each laser diode or bar, allowing individual control via a field effect transistor (FET) and current measuring resistor, enabling precise current control independent of temperature-dependent resistance, and a system control adjusts the bypass to maintain consistent light output across all diodes or bars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If laser bars are stacked to form high-power stacks, then optical power increases to approx. 1 kW, but beam homogeneity deteriorates due to production tolerances and aging differences
Solution Approach 1:
The patent divides the control of each laser bar into independent segments by providing individual bypass circuits for each bar. This allows separate control of current through each laser bar using FETs, enabling compensation for manufacturing tolerances and aging differences while maintaining high total power output.
Solution Approach 2:
The patent changes the electrical parameters (current) through each individual laser bar by adjusting bypass currents via FETs. This enables dynamic adjustment of each bar's contribution to the total beam, compensating for variations in light output characteristics and maintaining beam homogeneity despite production tolerances and aging.
2Manufacturing precision
If individual control of each laser bar is implemented, then beam homogeneity improves, but device complexity increases due to additional bypass components
Solution Approach 1:
The patent introduces bypass circuits with FETs as intermediary elements between the power source and each laser bar. These intermediaries enable precise control of current through each bar without requiring direct complex control of the laser bars themselves, simplifying the overall control architecture while achieving individual bar control.
Solution Approach 2:
The bypass circuits with FETs provide self-service control for each laser bar by automatically adjusting bypass current based on measured light output or desired intensity profiles. This reduces the need for complex external control systems while maintaining beam homogeneity and enabling individual bar adjustment.
3Manufacturing precision
If expensive optical corrections are used to improve beam homogeneity, then beam quality increases, but cost increases
Solution Approach 1:
The patent replaces expensive mechanical/optical correction systems with electrical control mechanisms. By using FETs to adjust current through each laser bar, the system achieves beam homogeneity through electrical means rather than requiring complex optical elements, significantly reducing cost while maintaining or improving beam quality.
Solution Approach 2:
The patent changes the approach from optical parameter adjustment to electrical parameter control. By controlling the electrical current through each laser bar individually, the system achieves the desired beam homogeneity through electrical parameter adjustment rather than expensive optical corrections.
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 solution enhances beam homogeneity and allows for adjustable radiation profiles, enabling efficient operation across various applications with improved power management and reduced costs.
Implementation Method 1
The current through the bypass is controlled with a field effect transistor (FET), in particular with a power FET
Implementation Method 2
a current measuring resistor is provided in each bypass
Implementation Method 3
A laser bar contains approx. 50 individual emitters, each of which emits a laser beam
Data Source
Figure 1
AI summary
In a laser diode arrangement for generating radiation having a predetermined intensity profile, comprising a horizontal or vertical stack (1) of laser diodes or laser bars (2) electrically connected in series, a by-pass (3) is provided for each diode or bar, with which the light output of each diode or bar is individually controllable. An independent claim is included for a method for controlling the laser diode arrangement, in which the laser output is adjusted via the current supply for each laser diode or laser bar (2) using a field effect transistor (5) and a current measuring resistor (4) in each by-pass (3).