Adaptive Optical Module Deflection Sensing via Impedance Gradients
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Solution Overview
Problem
Existing adaptive optical modules using piezoelectric or electrostrictive actuators face inaccuracies due to temperature variations, aging, defects, and drifts, leading to insufficient accuracy in surface shape corrections.
Innovation Solution
An adaptive optical module that measures impedance at different frequencies and working voltages to determine actuator deflection using gradient values of capacitance, enabling accurate surface shape corrections by interpolating susceptibility and polarization from measured impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric or electrostrictive actuators are used to alter the shape of an optical surface, then the optical module can correct wavefront errors and improve imaging precision, but temperature variations, aging, defects, and drifts in the actuator material cause considerable inaccuracies in the surface shape corrections
Solution Approach 1:
The patent implements a feedback mechanism by measuring the impedance of the actuator at different frequencies and working voltages, determining the deflection from gradient values of capacitance characteristic curves, and using this information to correct surface shape inaccuracies caused by actuator drift and material changes
Solution Approach 2:
The patent changes the measurement parameters by measuring impedance across multiple frequencies and working voltages rather than using a single fixed measurement point, allowing determination of gradient values that accurately reflect the actuator's actual state and enable precise deflection calculation
2Measurement precision
If a measuring electrode is arranged in the actuator material to measure temperature, then temperature-based corrections can be implemented, but this indirect measurement lacks sufficient accuracy in capturing surface shape errors caused by actuator deviations
Solution Approach 1:
The patent replaces the mechanical/thermal measurement approach (temperature sensing with measuring electrodes) with an electrical measurement approach (impedance measurement at different frequencies and voltages), which directly captures the actuator's electrical state and correlates more accurately with its mechanical deflection
Solution Approach 2:
The patent uses impedance measurement as an intermediary parameter that connects the electrical state of the actuator to its mechanical deflection state, allowing indirect measurement of surface shape errors through electrical characteristics rather than direct mechanical or thermal sensing
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 method allows for high-accuracy surface shape corrections by determining actuator deflection with improved precision, reducing inaccuracies caused by temperature variations and material changes.
Implementation Method 1
The actuator comprises a dielectric medium, which is deformable by an electric field, and electrodes for generating the electric field in the dielectric medium by application of an electrical working voltage
Implementation Method 2
a measuring device configured to measure an impedance present at different values of the working voltage between the electrodes as a function of a frequency of an AC voltage applied to the electrodes for measurement purposes
Data Source
AI summary
An adaptive optical module has at least one actuator for altering a shape of an optical surface of the optical module. The actuator comprises: a dielectric medium, which is deformable via an electric field, and electrodes for generating the electric field in the dielectric medium by applying an electrical working voltage. The adaptive optical module further comprises a measuring device that measures an impedance present at different values of the working voltage between the electrodes depending on a frequency of an AC voltage applied to the electrodes for measurement purposes, and an evaluation device configured to ascertain from the measured impedance approximately a respective gradient value of characteristic curves each representing a capacitance of the actuator depending on the frequency for the different values of the working voltage and to determine therefrom a deflection of the actuator at at least one operating point of the working voltage.