Lidar Autocalibration With Beam Sampling for Optical Alignment
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Solution Overview
Problem
Lidar devices used for atmospheric measurements face accuracy degradation due to environmental changes, component misalignment, and vibration, leading to compromised measurement performance.
Innovation Solution
A lidar assembly with a calibrator subsystem that includes a beam sampler, calibrator lens assembly, and scattering plate to create a backscattered calibrator beam, allowing for automatic calibration by comparing measurement signals with and without the calibrator beam, adjusting for changes in optical sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lidar device operates continuously in outdoor environmental conditions, then the device can perform atmospheric measurements, but the measurement accuracy degrades due to temperature changes, vibration, and component misalignment
Solution Approach 1:
The patent implements a calibrator subsystem that performs preliminary calibration actions by directing a calibrator beam through the optical system to a known reference position. This preliminary calibration compensates for environmental changes before they significantly impact measurement accuracy, allowing the lidar to maintain reliability despite outdoor temperature variations and vibration.
Solution Approach 2:
The system uses feedback by comparing the position of the calibrator beam at a known reference point against expected values. This feedback mechanism detects deviations caused by environmental factors and triggers realignment or compensation actions, thereby maintaining measurement accuracy despite harmful environmental effects.
2Ease of repair
If lidar components are replaced in field conditions, then the device can be maintained, but alignment between transmitter, receiver and optical system is lost
Solution Approach 1:
The calibrator subsystem enables self-service calibration after component replacement. The automatic calibration process uses the calibrator beam to detect misalignment and guide realignment actions, allowing the lidar to self-correct without requiring manufacturer-level precision during field maintenance operations.
Solution Approach 2:
The patent replaces complex mechanical alignment procedures with an optical-based automated calibration system. Instead of requiring precise mechanical repositioning of components during replacement, the system uses optical feedback from the calibrator beam to guide and verify alignment, substituting mechanical precision requirements with optical detection and control.
3Reliability
If a calibration subsystem is added to the lidar, then measurement accuracy can be maintained, but device complexity increases
Solution Approach 1:
The calibrator subsystem is designed to share optical paths and components with the main measurement system. The beam sampler, optical arrangement, and detection mechanisms serve dual purposes: normal atmospheric measurement and self-calibration functions. This multi-functionality reduces the need for completely separate calibration hardware, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The patent introduces a beam sampler as an intermediary element that extracts a portion of the transmitter beam for calibration purposes without significantly interfering with the main measurement beam. This intermediary approach allows calibration functionality to be added with minimal impact on the primary system architecture, reducing the complexity burden of the calibration subsystem.
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
Improves measurement accuracy and reliability by compensating for changes in transmitter power, receiver sensitivity, and optical alignment over time, ensuring consistent calibration.
Implementation Method 1
a beam sampler, arranged between the beam reflector and the primary lens assembly, for reflecting a portion of the transmitter beam as a calibrator beam
Implementation Method 2
a first scattering plate arranged to produce a diffuse reflection of the calibrator beam meeting its surface, thereby invoking a backscattered calibrator beam
Implementation Method 3
a primary lens assembly for collimating a transmitter beam originating from a first focal point within the lidar assembly to illuminate a target at a distance from the lidar assembly and for focusing a backscattered light from the target to a second focal point within the lidar assembly
Implementation Method 4
a primary lens assembly for collimating a transmitter beam originating from a first focal point within the lidar assembly to illuminate a target at a distance from the lidar assembly and for focusing a backscattered light from the target to a second focal point within the lidar assembly
Implementation Method 5
a beam reflector, arranged between the first focal point and the primary lens assembly, for reflecting the backscattered light towards said second focal point
Data Source
Figure 1~2A
Figure 2B~3A
Figure 3B~4
AI summary
According to an example embodiment, a lidar assembly (300, 300', 300") for atmospheric measurements is provided, the lidar assembly comprising a primary lens assembly (103) for collimating a transmitter beam originating from a first focal point within the lidar assembly (300, 300', 300") to illuminate a target at a distance from the lidar assembly (300, 300', 300") and for focusing a backscattered light from the target to a second focal point within the lidar assembly (300, 300', 300"); a transmitter (101), arranged in said first focal point, for generating said transmitter beam for transmission towards the primary lens assembly (103); a receiver (102), arranged in said second focal point, for capturing said backscattered light entering the lidar assembly (300, 300', 300") through the primary lens assembly (103); a beam reflector (104), arranged between the first focal point and the primary lens assembly (103), for reflecting the backscattered light towards said second focal point such that the beam reflector (104) allows the transmitter beam to reach the primary lens assembly (103), wherein the lidar assembly (300, 300', 300") comprises a calibrator subsystem comprising: a beam sampler (215), arranged between the beam reflector (104) and the primary lens assembly (103), for reflecting a portion of the transmitter beam as a calibrator beam; and an optical arrangement for transferring the calibrator beam towards a selected one of a plurality of targets in the calibrator subsystem wherein said plurality targets include at least the following: a first scattering plate (216) arranged to produce a diffuse reflection of the calibrator beam meeting its surface, thereby invoking a backscattered calibrator beam for transfer to the receiver (102) via said optical arrangement, via the beam sampler (215) and via the beam reflector (104), and at least one element (219, 220) arranged to prevent provision of the backscattered calibrator beam.