Solid-State LiDAR Transmitter Layout for Uniform VCSEL Emission
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Solution Overview
Problem
Solid-state LiDARs face issues with non-uniform light emission due to high aspect ratios of VCSEL arrays, leading to voltage drops and reduced luminance across lasers, affecting distance measurement precision and detection accuracy.
Innovation Solution
The design includes multiple transmitting modules with light emitting units arranged in a strip shape, where each module is electrically connected through an electrode unit with driving terminals, and a blindness-compensation laser is added to improve detection range and reduce blind areas, while the receiving module features a light splitting unit to separate and process detection beams effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple lasers are connected in parallel to form a light emitting unit with high current and high frequency drive, then the detection range and coverage are improved, but voltage drop due to resistance and parasitic inductance causes non-uniform light emission and reduced detection precision
Solution Approach 1:
The patent divides the light emitting unit into multiple groups, with each group containing a subset of lasers that are driven independently. This segmentation allows the drive line to be divided into shorter segments, reducing the length of each parallel connection and thereby minimizing voltage drop and parasitic inductance effects. Each group can be driven with optimized current and frequency parameters to maintain uniform light emission across all lasers while achieving comprehensive detection coverage.
2Area of stationary object
If the light emitting unit is made extremely long to cover larger detection area, then the field of view coverage is improved, but the aspect ratio increases causing voltage drop and non-uniform luminance distribution
Solution Approach 1:
The light emitting unit is segmented into multiple groups along its length, with each group containing lasers that are driven by separate drive lines. This segmentation reduces the effective length of each drive line, minimizing voltage drop and ensuring that lasers at different positions along the extended light emitting unit receive sufficient and uniform driving current, thereby maintaining luminance uniformity across the entire large-area coverage.
Solution Approach 2:
The patent arranges lasers in a two-dimensional array structure rather than a simple linear sequence. By organizing lasers in rows and columns with independent group driving, the system can achieve large field of view coverage in multiple dimensions while keeping individual drive line lengths manageable. This dimensional reorganization allows comprehensive coverage without proportionally increasing the aspect ratio problems of single-dimensional extensions.
3Length of stationary object
If high current drive is used to increase detection range, then the detection range is improved, but heat dissipation increases affecting system stability
Solution Approach 1:
The patent implements periodic pulsing of laser groups, where different groups are activated in alternating time intervals rather than continuously. This periodic operation allows each group to operate at high current for short pulses to achieve detection range, followed by rest periods that reduce cumulative heat generation. The duty cycle is optimized to maintain sufficient detection capability while limiting temperature rise and heat dissipation requirements.
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 configuration reduces non-uniformity in light emission, enhances ranging performance, and increases detection accuracy by reducing blind areas and heat dissipation, while maintaining safety and improving optical power.
Implementation Method 1
a light source which is a high-density vertical cavity surface-emitting laser (VCSEL) array
Implementation Method 2
a detection unit including a plurality of photodetectors configured to receive echoes
Implementation Method 3
a detection unit including a plurality of photodetectors configured to receive echoes of the detection beams
Data Source
AI summary
A solid-state laser radar, including: a plurality of emission modules, each emission module including at least one light-emitting unit, and the light-emitting unit including a plurality of lasers configured to emit detection beams at the same time; and a receiving module, including at least one detection unit, the detection unit including a plurality of photodetectors configured to receive echoes, reflected by a target object, of the detection beams, the plurality of emission modules are disposed around the receiving module, the light-emitting units of the plurality of emission modules are located on a same plane, and one detection unit is configured to receive echoes, reflected by the target object, of the detection beams emitted by the light-emitting units of the plurality of emission modules. For a set range of field angles, the lengths of the light-emitting units emitting light simultaneously are greatly reduced by providing the plurality of emission modules.