Laser Diode Bar Lighting Device Smile Distortion Correction
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Solution Overview
Problem
Existing lighting devices with laser diode bars suffer from 'smile' distortion due to production-related bending, leading to suboptimal beam parameter product and focusability, as the partial beams do not propagate parallel to each other after beam transformation, resulting in enlarged angular distribution and reduced beam quality.
Innovation Solution
A lighting device with a prism array or telescope array is used to correct the Poynting error caused by 'smile' distortion, where prism or telescope elements are designed to adjust their surfaces to compensate for height offsets, ensuring parallelization of partial beams and reducing divergence, and a beam expansion means is employed to further improve beam quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a beam transformation means with cylindrical lens segments is used to symmetrize the beam parameter product, then the partial beams undergo common beam rotation and the beam symmetry is improved, but the distance between individual partial beams increases and the beam parameter product in the long axis deteriorates
Solution Approach 1:
The beam transformation means is segmented into multiple cylindrical lens segments arranged in parallel, with each segment processing a specific partial beam. This segmentation allows independent optimization of each beam path while maintaining overall beam symmetry, resolving the contradiction between beam symmetry improvement and excessive distance between partial beams.
Solution Approach 2:
The patent introduces a second spatial dimension by arranging cylindrical lens segments in parallel along the long axis direction. This dimensional arrangement allows the transformation of beam parameters in one dimension (short axis symmetry) without excessively increasing distances in another dimension (long axis spacing), thus resolving the contradiction.
2Productivity
If a telescope array with multiple telescope means is arranged behind the beam transformation means to reduce divergence and close gaps between partial beams, then the beam parameter product is improved, but the device complexity increases and the solution fails due to smile distortion
Solution Approach 1:
The patent merges the beam transformation function and the divergence reduction function into a single integrated optical system. The cylindrical lens segments perform both beam rotation and divergence control simultaneously, eliminating the need for a separate telescope array and reducing device complexity while maintaining improved beam parameter product.
Solution Approach 2:
The cylindrical lens segments are designed to perform multiple functions: beam rotation, symmetry improvement, and divergence control. This multi-functionality replaces the need for separate specialized components like telescope arrays, reducing overall device complexity while achieving the desired beam parameter improvement.
3Device complexity
If the lighting device does not compensate for smile distortion, then the device complexity is reduced, but the Poynting error increases and the angular distribution envelope is enlarged
Solution Approach 1:
The patent applies local quality by making each cylindrical lens segment individually adjustable in position and orientation. This allows localized compensation for smile distortion at each emitter location without requiring a complex global adjustment system. Each segment can be independently optimized to correct Poynting errors for its corresponding partial beam, maintaining beam pointing accuracy while keeping device complexity manageable.
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 compensates for 'smile' distortion, bringing the beam parameter product close to its theoretical limit, thereby enhancing the focusability and quality of the laser beam, allowing it to be efficiently coupled into optical fibers.
Implementation Method 1
When a linear laser beam impinging on the beam transformation means passes through, as can be generated by the laser diode bar, the partial beams undergo a common beam rotation of 90° when passing through the beam transformation means
Implementation Method 2
The partial beams emitted by the individual emitters of the laser diode bar have a significantly greater divergence in the fast-axis direction than in the slow-axis direction
Data Source
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AI summary
The invention relates to a lighting device (1) comprising: at least one laser-diode bar (100) with a plurality of emitters (101, 102, 103) which are arranged adjacently to one another in a first direction and can emit sub-beams (10, 11, 12) during operation, said sub-beams having a lower beam divergence in a first direction that forms a slow-axis direction than in a second direction that forms a fast-axis direction and is perpendicular to the first direction, and at least some of the emitters (101, 102, 103) having a height offset in relation to the other emitters (101, 102, 103); a fast-axis collimation means (2) positioned behind the at least one laser-diode bar (100) in a beam-propagation direction perpendicular to the slow-axis direction and the fast-axis direction; a beam transformation means (3) positioned behind the fast-axis collimation means (2) in the beam-propagation direction and designed to rotate the sub-beams (10, 11, 12) through 90° as they pass through said means. The lighting device (1) also comprises a prism array (4) positioned behind the beam transformation means (3) in the beam-propagation direction and a number of prism means (40, 40') corresponding to the number of emitters (101, 102, 103) and arranged adjacently to one another in the first direction, each of which has an incident light face (400, 400') and a light output face (401, 401') for one of the sub-beams (10, 11, 12). The incident light faces (400') and/or the light output faces (401') of the prism means (40'), through which the sub-beams (12) with a height offset pass, are designed such that the Poynting effect can be corrected by the parallelization of said sub-beams (12).