Laser Radar Optical Axis Corrector for Wind Measurement

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Solution Overview

Problem

Laser radar devices face a reduction in wind measurement rate and signal intensity due to optical axis angular shifts between transmission and received light beams during beam scanning, which become more pronounced with increased scanning speed and distance.

Innovation Solution

A laser radar device equipped with an optical axis corrector using two wedge prisms and a rotation controller to correct the angular shift by maintaining a relative angular difference, allowing for simultaneous rotation control based on beam scanning speed and wind measurement distance, thereby maintaining signal intensity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If beam scanning speed is increased to improve wind measurement rate, then productivity increases, but optical axis angular shift between transmission and received light increases causing signal intensity reduction

Engineering Contradiction:
Improvewind measurement rateVSAvoidsignal intensity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The optical axis corrector proactively compensates for the optical axis angular shift before it significantly degrades the received signal. By using wedge prisms that rotate in opposition to the beam scanning-induced angular shift, the system preemptively counteracts the harmful effect, allowing high-speed scanning without signal loss.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The wedge prism acts as an intermediary optical element between the beam scanner and the received light path. It introduces a compensating angular shift that mediates the mismatch between transmission and received light optical axes, enabling high-speed scanning while maintaining coupling efficiency.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If beam scanning is performed to enable multi-directional wind measurement, then adaptability increases, but optical axis angular shift occurs reducing measurement precision

Engineering Contradiction:
Improvewind measurement direction coverageVSAvoidreceived signal intensity
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The optical axis corrector dynamically adjusts the wedge prism rotation angle based on the real-time beam scanning position and angle. This dynamic compensation ensures that the optical axis alignment is maintained throughout the entire scanning range, enabling multi-directional measurement without precision loss.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system uses feedback from the beam scanning controller about the current scanning angle and position to adjust the wedge prism rotation accordingly. This closed-loop control ensures that the optical axis compensation is continuously optimized for the current measurement direction.

Inventive Principle:
Principle #23Feedback

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-speed wind measurement without reducing signal intensity, allowing for distant wind measurement and flexible adjustment of optical axis shifts to accommodate varying scanning speeds.

Implementation Method 1

an optical axis corrector configured to correct an optical axis angular shift occurring between a transmission light beam and a received light beam owing to the beam scanning

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

the laser radar device obtains a Doppler shift caused by the movement of the aerosols through heterodyne detection between the received light and the local light of the transmission light

Methodology Applied
Scientific EffectDoppler effect: Doppler Effect

Implementation Method 3

the laser radar device obtains a Doppler shift caused by the movement of the aerosols through heterodyne detection between the received light and the local light of the transmission light

Methodology Applied
Scientific EffectHeterodyne detection: Heterodyne

Data Source

PatentEP3249422B1Laser radar device
Publication Date: 2021.12.29 MITSUBISHI ELECTRIC CORP
  • EP3249422B1 patent drawingFigure 1
  • EP3249422B1 patent drawingFigure 2
  • EP3249422B1 patent drawingFigure 3

AI summary

A device includes a light source (1) for generating light with a single wavelength; a modulator (3) for modulating the light generated into transmission light; a beam scanner (7) for carrying out beam scanning by which the transmission light modulated is radiated, and the light reflected is received; a beam scanning controller (8) for controlling the radiation direction; a signal processing unit (12) for performing wind measurement through heterodyne detection using the light generated and the corresponding received light; and an optical axis corrector (9) for correcting the optical axis angular shift between the transmission light and the received light, which accompanies the beam scanning, with respect to the received light used by the signal processing unit (12) or the transmission light used by the beam scanner (7), on the basis of the radiation direction of the beam scanner (7), the angular speed of the beam scanning and the wind measurement distance.