Automotive LiDAR Filter Tracking Laser Thermal Wavelength Drift
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
LIDAR systems in motor vehicles face limitations in signal quality due to temperature-induced wavelength shifts of semiconductor lasers, requiring broad bandpass filters to compensate, which increases interfering light and reduces performance.
Innovation Solution
A LIDAR system incorporating a monolithic frequency-stabilized semiconductor laser with a bandpass filter that matches its thermal wavelength shift, using materials like amorphous silicon to maintain a narrow passband over a broad temperature range without laser temperature stabilization, thereby reducing complexity, cost, and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a narrow bandpass filter is used to maintain signal quality, then signal-to-noise ratio is improved, but the laser wavelength must be precisely stabilized against temperature changes, increasing device complexity
Solution Approach 1:
The patent changes the thermal wavelength shift parameter of the bandpass filter by using amorphous silicon instead of conventional dielectric materials. This parameter change allows the filter to compensate for laser wavelength drift without requiring active temperature stabilization, thus maintaining signal quality while reducing device complexity
Solution Approach 2:
The patent converts the harmful thermal wavelength shift of the semiconductor laser into a beneficial effect by matching it with a bandpass filter that has a corresponding thermal wavelength shift. The filter's wavelength shift, which would normally be considered a deviation, actually tracks the laser's wavelength drift, maintaining alignment without active stabilization
2Device complexity
If a broad bandpass filter is used to accommodate temperature-induced wavelength shifts, then device complexity is reduced, but signal quality deteriorates due to increased interfering light
Solution Approach 1:
The patent changes the material parameter of the bandpass filter from conventional dielectric materials to amorphous silicon, which has a significantly different thermal wavelength shift characteristic. This parameter change enables the filter to maintain a narrow passband while tracking the laser's wavelength drift with temperature, thus improving signal quality without requiring broad filtering
3Measurement precision
If active temperature stabilization of the laser is implemented, then wavelength stability is improved, but power consumption and cost increase
Solution Approach 1:
The patent implements a self-service mechanism where the bandpass filter automatically compensates for the laser's wavelength drift through its intrinsic thermal wavelength shift property. The amorphous silicon filter naturally tracks the laser's temperature-induced wavelength changes, eliminating the need for external active temperature stabilization systems, thus reducing power consumption
Solution Approach 2:
The patent converts the harmful thermal sensitivity of semiconductor lasers into a beneficial tracking mechanism by pairing it with a thermally sensitive amorphous silicon bandpass filter. Both components respond similarly to temperature changes, causing their wavelength shifts to cancel out, thereby achieving wavelength stability without active power-consuming stabilization
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
Enables efficient filtering of background light and maintains signal quality across varying temperatures without the need for laser temperature stabilization, enhancing the LIDAR system's operational range and reducing interference.
Implementation Method 1
The bandpass filter is used to improve the signal-to-noise ratio by filtering out background light and includes, for example, an interference filter or a filter which uses a combination of interference and absorption effects
Implementation Method 2
A multilayer interference filter is known from DE 4424717 A1, which includes layers made of hydrogenous amorphous silicon, where a dλ/dt of the two mirror layers is able to be equal, so that a change of the temperature results in a shift of the central wavelength with consistency of the transmission breadth
Data Source
AI summary
A LIDAR system includes a monolithic frequency-stabilized semiconductor laser having a linear thermal wavelength shift and a bandpass filter that is configured to effectuate a thermal wavelength shift that does not deviate from the linear thermal wavelength shift of the semiconductor laser by more than 40%, and a temperature stabilization of the semiconductor laser can be dispensed with by the use of the invention. The LIDAR system can be provided in a control system that includes a control unit that controls obstacle avoidance of a motor vehicle based on an obstacle distance determined by the LIDAR system.