Integrated Optical Filter Lidar for Miniaturized Speed Measurement
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Solution Overview
Problem
Conventional Doppler lidar devices face challenges in achieving a single-mode laser light source with short pulse width, narrow spectral line width, and high output, which is difficult to miniaturize and costly, especially when using semiconductor laser diodes or solid-state laser sources.
Innovation Solution
A lidar device utilizing a multimode laser light source in conjunction with a narrow-band filter and an edge filter, where the filters are integrally formed to convert the multimode laser light into narrow-band light, enabling accurate measurement of relative target speed without requiring a single-mode laser source, and reducing device size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single-mode laser light source is used to ensure narrow spectral line width and high output, then measurement accuracy is improved, but device size increases and miniaturization becomes difficult
Solution Approach 1:
The patent combines the narrow-band filter and edge filter into a single integrated filter component. This merging reduces the number of separate optical components, thereby miniaturizing the device while maintaining the narrow spectral line width required for accurate Doppler measurements using a multimode laser source
2Measurement precision
If a single-mode laser light source with short pulse width is used to achieve high distance resolution, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the approach from modifying the laser source parameters (single-mode, short pulse width) to modifying the optical filter parameters. By using a multimode laser with short pulse width combined with integrated narrow-band and edge filters, the system achieves high distance resolution while reducing device complexity and cost
3Ease of manufacture
If a multimode laser light source is used to reduce device size and cost, then ease of manufacture is improved, but spectral line width increases reducing measurement accuracy
Solution Approach 1:
The integrated narrow-band filter acts as an intermediary between the multimode laser source and the target. It converts the wide-spectral multimode laser light into narrow-band light with a sharp spectral peak, enabling accurate Doppler measurements while allowing the use of easier-to-manufacture multimode laser sources
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 high-accuracy measurement of target relative speed using a multimode laser source, achieving high distance resolution and reducing manufacturing costs while allowing for miniaturization of the lidar device.
Implementation Method 1
a narrow-band filter for converting output laser light of the multimode laser light source into narrow-band laser light
Implementation Method 2
a lidar called a Doppler lidar can measure a relative moving speed of a target using laser light backscattered by the target. As a method for detecting the Doppler effect, a coherent system using optical heterodyne detection and an incoherent system using an optical filter (direct detection system) are known.
Implementation Method 3
a light detection circuit for detecting a transmission light signal output by the edge filter and generating an electric signal corresponding to the transmission light signal
Data Source
AI summary
The lidar device includes a multimode laser light source, a narrow-band filter for converting output laser light of the multimode laser light source into narrow-band laser light, an edge filter for receiving backscattered light generated when a target (Tgt) in an external space backscatters the narrow-band laser light, a light detection circuit for detecting a transmission light signal output by the edge filter and outputting an electric signal, and a signal processing unit for measuring at least a relative speed of the target (Tgt) on the basis of the electric signal. The light transmission characteristic of the narrow-band filter has a first narrow-band spectrum that forms a peak of light transmittance at a predetermined light transmission frequency, and the light transmission characteristic of the edge filter has a second narrow-band spectrum having an edge portion forming a positive or negative gradient of light transmittance at the light transmission frequency.