Speckle Tracking Sensor Vibrational Noise Correction
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Solution Overview
Problem
Existing vibration remote sensors based on speckle tracking are affected by their own vibrations and microseismic noise, which limits their ability to accurately measure angular velocities and other kinematic parameters over long distances.
Innovation Solution
The use of an optical-inertial accelerometer integrated with the speckle-tracking remote sensor to correct vibrational noise, allowing for precise measurement of angular velocities and other parameters by compensating for the sensor's own movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If speckle tracking remote sensor is used to measure vibrations over long distances, then measurement range is improved, but measurement precision deteriorates due to vibrational noise and microseismic effects
Solution Approach 1:
An optical-inertial accelerometer is introduced as an intermediary device to measure the vibrational noise and microseismic effects affecting the remote sensor. The accelerometer's output serves as a reference signal that mediates the correction process, allowing the system to distinguish between target vibrations and sensor-induced noise even at long distances
Solution Approach 2:
A feedback mechanism is implemented where the accelerometer continuously monitors the sensor platform's vibrations and feeds this information back to the correction algorithm. The algorithm uses this feedback to dynamically adjust and subtract the noise components from the measured speckle pattern, maintaining measurement precision across extended measurement ranges
2Device complexity
If conventional vibration correction methods are used, then device complexity is reduced, but measurement reliability deteriorates in the presence of microseismic noise
Solution Approach 1:
The patent replaces complex mechanical vibration isolation systems with an optical-inertial sensing and computational correction approach. Instead of using heavy mechanical dampers or active vibration isolation tables, the system uses optical detection combined with inertial measurement and algorithmic correction, achieving higher reliability with reduced mechanical complexity
Solution Approach 2:
The accelerometer creates a copy of the vibrational noise affecting the optical sensor. By measuring the platform vibrations independently through the accelerometer, the system generates a reference copy of the noise that can be subtracted from the optical measurement, improving reliability without requiring complex physical isolation
3Measurement precision
If optical lever effect is exploited to enhance sensitivity, then measurement sensitivity is improved, but susceptibility to sensor vibrations increases
Solution Approach 1:
The accelerometer acts as an intermediary that measures and characterizes the sensor vibrations causing the harmful effects. By introducing this independent measurement channel, the system can identify and correct the vibration-induced errors that amplify with the optical lever effect, maintaining high sensitivity while reducing vulnerability to self-vibrations
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
The solution effectively reduces the impact of vibrational noise, enabling the remote sensor to achieve the required sensitivity and accuracy specifications, such as sensitivity at 30 m > 2 · 10−8 rad and accuracy at 15 m ±5 · 10−8 rad, even at long distances.
Implementation Method 1
when a coherent beam of light illuminates a rough surface, the light is scattered, thus resulting in a random (but time-stationary) diffraction pattern, commonly called a speckle pattern
Implementation Method 2
the light is scattered, thus resulting in a random (but time-stationary) diffraction pattern
Implementation Method 3
an optical-inertial accelerometer integrated with the speckle-tracking remote sensor to correct vibrational noise
Implementation Method 4
A receiver optical system, which ends in a photosensor (CCD), receives the granular image of the moving speckles
Data Source
AI summary
A remote sensor based on speckle tracking which uses an inertial-optical accelerometer is provided. The remote sensor makes it possible to correct the speckle pattern correlation centroid value in the presence of displacements due to vibrational noise. The inertial-optical accelerometer instantaneously highlights displacements of the sensor relative to an inertial reference, that is of a mass immovable with respect to the fixed stars, installed in the optical axis of the remote sensor.