Lidar Holographic Optical Element Wavelength-Angle Coordination
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Solution Overview
Problem
Conventional LIDAR devices face challenges in achieving a high signal-to-noise ratio and efficient beam deflection due to the broad spectral width of broad area lasers and the need for wider optical bandpass filters at larger angles, which compromises signal quality and increases complexity.
Innovation Solution
The use of holographic optical elements that diffract electromagnetic radiation based on wavelength and angle, allowing for a tailored bandpass filter configuration that reduces filter bandwidth and improves signal quality, especially when combined with a broadband beam source, enabling a smaller filter bandwidth to be used even at large angles of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a broad area laser with large spectral width is used as beam source, then the laser provides high optical output, but the spectral width is large which reduces signal quality
Solution Approach 1:
The patent segments the broad spectral output of the laser into multiple narrow wavelength ranges using a dispersive element (prism or grating). Each wavelength range is spatially separated and directed to a corresponding detector pixel, effectively dividing the broad spectrum into manageable narrow bands that can be processed with appropriate bandpass filters.
Solution Approach 2:
The patent introduces a spatial dimension to wavelength separation by using a dispersive element that angularly disperses different wavelengths. This spatial separation allows each wavelength component to be independently filtered and detected, transforming a spectral problem into a spatial-multiplexed solution.
2Adaptability or versatility
If the field of view is increased, then the angular range is expanded, but the filter bandwidth must be increased which reduces signal quality
Solution Approach 1:
The patent divides the field of view into multiple angular sectors, each corresponding to a specific wavelength range. By segmenting both the angular space and spectral space, the system can use narrow bandpass filters for each sector while collectively covering a wide field of view through the combined output of multiple pixels.
Solution Approach 2:
The patent adds a spectral dimension to the angular field of view. Instead of using a single wide-band filter that degrades signal quality, the system creates a two-dimensional detection space (angle × wavelength) where each pixel detects a specific combination of angle and wavelength, allowing narrow filters to be used in each dimension while maintaining wide overall coverage.
3Measurement precision
If a narrow optical bandpass filter is used, then the signal-to-noise ratio is improved, but the field of view must be limited to small angles
Solution Approach 1:
The patent segments the field of view and spectral content across multiple detector pixels. Each pixel is equipped with a narrow bandpass filter optimized for its specific wavelength range and angular sector. This segmentation allows each pixel to achieve high signal-to-noise ratio with narrow filters while the aggregate system maintains a wide field of view through the combined coverage of all pixels.
Solution Approach 2:
The patent creates a multi-functional detection system where each pixel serves multiple purposes: spatial detection, spectral filtering, and angular measurement. The combination of dispersive element, narrow bandpass filters, and array detector enables the system to simultaneously achieve narrow effective bandwidth per channel and wide overall field of view coverage.
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 approach enhances the signal-to-noise ratio and performance of LIDAR devices by coordinating angle and wavelength, allowing for a more compact and cost-effective design with improved range and reduced optical complexity.
Implementation Method 1
at least one holographic optical element is situated in the emission path for diffracting the emitted electromagnetic radiation
Implementation Method 2
This diffraction may be implemented in volume holograms by diffraction at the volume grating
Implementation Method 3
An optical bandpass filter (interference filter) is used in the reception path of the LIDAR device in order to improve the signal-to-noise ratio. This occurs in that background light is filtered out and the usable electromagnetic radiation is transmitted
Implementation Method 4
The beam source for emitting electromagnetic radiation may be designed as a semiconductor laser
Implementation Method 5
The spectral distribution of the emitted electromagnetic radiation is therefore only defined by the wavelength-dependent yield of the semiconductor structure and by the laser process itself
Data Source
AI summary
A LIDAR device is described including a beam source for emitting electromagnetic radiation in an emission path, in which at least one holographic optical element is situated for diffracting the emitted electromagnetic radiation, and a detector for detecting incident electromagnetic radiation in a reception path, an optical bandpass filter being connected upstream from the detector. Depending on a wavelength of the emitted electromagnetic radiation, the holographic optical element effectuates a diffraction by at least one angle of reflection which is matched to the shift of the wavelength of the incident electromagnetic radiation with the aid of the bandpass filter.