Edge Emitting Laser Light Uniformity via Reflecting Mirror
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Solution Overview
Problem
Current time-of-flight technology using surface emitting lasers is limited by low power and restricted measurement distance and wavelength, leading to uneven light intensity and insufficient emission angles, which affects applications like 3D image measurement and face recognition.
Innovation Solution
A light emitting device and module utilizing an edge emitting laser chip with a reflecting mirror, where light beams are projected onto a virtual incident plane to create non-overlapping light spots, improving light uniformity and emission angles through a diffuser, thereby enhancing luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high-power edge emitting laser is used instead of a surface emitting laser, then the power and measurement distance are improved, but the light shape becomes uneven and speckle effect occurs
Solution Approach 1:
The patent divides the single laser beam from the edge emitting laser into multiple parallel light beams using a beam splitting structure. This segmentation approach distributes the high power across multiple beams, reducing the intensity concentration that causes speckle effects and uneven light distribution, while maintaining the overall high power output advantage.
Solution Approach 2:
The patent employs a diffuser with spatially varying optical properties to uniformly distribute the light from different emitting ports. The diffuser's local optical characteristics are optimized to compensate for the inherent non-uniformity of edge emitting laser light, achieving uniform illumination across the entire light output while preserving the high power advantage.
2Power
If a high-power edge emitting laser is used instead of a surface emitting laser, then the power is improved, but the emission angle becomes insufficient
Solution Approach 1:
The patent arranges multiple light emitting ports in parallel along a first direction, with each port emitting light in a second direction perpendicular to the first. This orthogonal arrangement effectively increases the emission angle in the first direction without compromising the power output in the second direction, solving the emission angle limitation of conventional edge emitting lasers.
3Power
If multiple light beams are emitted from edge emitting laser ports, then the power is improved, but the light beams may overlap and cause uneven luminous intensity
Solution Approach 1:
The patent introduces a diffuser as an intermediary optical element between the multiple light emitting ports and the target. This diffuser uniformly scatters and redistributes the light from all ports, ensuring that the combined light output maintains high total power while achieving uniform luminous intensity distribution without beam overlap issues.
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 improves light uniformity and emission angles, addressing the limitations of surface emitting lasers, and facilitates better image information acquisition in applications like 3D measurement and face recognition.
Implementation Method 1
The reflecting mirror includes a reflecting surface used to reflect the light beams to a third direction perpendicular to the first direction and the second direction
Implementation Method 2
The diffuser is used to receive the light beams reflected by the reflecting surface
Data Source
AI summary
A light emitting device includes an edge emitting laser chip and a reflecting mirror. The edge emitting laser chip has light emitting ports arranged in parallel in a first direction. The light emitting ports emit light beams in a second direction. The reflecting mirror includes a reflecting surface used to reflect the light beams to a third direction. The first, second and third direction are perpendicular to each other. The light beams are emitted to the reflecting surface through the virtual incident plane and project first light spots on the reflecting surface. Each projected light spot has a first axis length in the first direction and a third axis length in the third direction. An interval between two immediately-adjacent light emitting ports is greater than the first axis length of one of the two projected light spots aligned with the two immediately-adjacent light emitting ports.