Dual-mode electro-optic sensor wavefront error estimation
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Solution Overview
Problem
Dual-mode electro-optic sensors face challenges in accurately estimating wavefront errors in primary optical elements due to thermal loading and manufacturing defects, which degrade performance, especially in high-resolution passive imaging modes, and existing methods for measurement are expensive, complex, and unsuitable for field testing.
Innovation Solution
The use of active guidance radiation as a 'guide star' to generate an artificial point source for in-situ wavefront error estimation, allowing for the spatial encoding of wavefront tilt deviations and processing these signals to provide a wavefront error estimate for the primary optical element, which can be used to deform or redesign the optics, without interfering with normal sensor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional interferometer or Shack-Hartman wavefront sensor is used to measure wavefront error, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent makes the existing dual-mode sensor perform multiple functions: it simultaneously provides guidance functionality and wavefront error measurement. The sensor uses its own imaging detector and optical path to extract wavefront information, eliminating the need for separate specialized measurement equipment like interferometers or Shack-Hartman sensors.
Solution Approach 2:
The sensor system measures its own wavefront errors using its existing components. The imaging detector captures images that contain wavefront information, and the processor extracts this information through image processing algorithms, allowing the system to self-diagnose and self-correct without external measurement equipment.
2Measurement precision
If traditional wavefront measurement equipment is used, then measurement accuracy is improved, but ease of operation deteriorates due to requiring experienced engineers
Solution Approach 1:
The system automatically performs wavefront error measurement and compensation without requiring operator intervention. The processor automatically extracts wavefront information from captured images and generates correction signals, eliminating the need for experienced engineers to perform manual measurements.
Solution Approach 2:
The patent replaces complex manual measurement procedures with automated image processing algorithms. Instead of requiring engineers to operate sophisticated measurement equipment, the system uses software-based analysis of standard images to automatically determine wavefront errors.
3Measurement precision
If existing wavefront measurement methods are used, then measurement precision is improved, but adaptability deteriorates as they are not suitable for field testing
Solution Approach 1:
The patent enables the sensor to perform both guidance operations and wavefront measurement in the same operational environment. The system can conduct wavefront measurements during normal sensor operation in field conditions, making the measurement capability adaptable to various operational scenarios including field testing.
Solution Approach 2:
The sensor system is self-sufficient for wavefront measurement, requiring no external equipment or controlled environment. It uses its own imaging detector and processing capabilities to perform measurements in-situ, enabling field testing and operational validation without returning to a laboratory setting.
4Manufacturing precision
If high-resolution passive imaging mode is used, then imaging performance is improved, but wavefront errors from thermal loading and manufacturing defects have greater negative impact
Solution Approach 1:
The system continuously measures wavefront errors using the imaging detector and automatically generates correction signals to actuators that adjust the primary optical element. This closed-loop feedback compensates for thermal loading and manufacturing defects in real-time, maintaining high imaging performance despite environmental variations.
Solution Approach 2:
The patent dynamically adjusts the shape of the primary optical element using actuators based on measured wavefront errors. By changing the physical parameter (surface shape) of the optical element in response to environmental conditions, the system compensates for thermal loading effects and maintains optimal imaging performance.
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
This approach enables accurate and efficient wavefront error estimation and compensation within the dual-mode sensor, improving target positioning and imaging performance without the need for external, expensive equipment, and is suitable for field use.
Implementation Method 1
a primary optical element having a common aperture for collecting and focusing SAL laser radiation and passive imaging radiation along a common optical path
Implementation Method 2
A secondary optical element separates the SAL laser and passive imaging radiation by spectral band
Implementation Method 3
The optics spatially encode an angle of incidence of the SAL laser radiation (e.g. a laser spot) at an entrance pupil onto the SAL detector
Implementation Method 4
In a semi-active laser (SAL) mode, the sensor detects active guidance radiation in the form of laser radiation from a SAL designator that is reflected off of the target
Implementation Method 5
In a passive imaging mode, the sensor detects IR radiation emitted from or reflected off of the target
Implementation Method 6
The sources of IR energy are not artificial; they typically follow the laws of Planck radiation. The source may be the blackbody radiation emitted by the target directly
Implementation Method 7
The wavefront error estimate may be used to control actuators to compensate a deformable primary optical element to reduce wavefront errors
Data Source
AI summary
A dual-mode sensor uses the active guidance radiation as a “guide star” to generate a wavefront error estimate for the primary optical element in-situ without interfering with the generation of either the active guidance or passive imaging guidance signals. An array of optical focusing elements performs the normal function of spatially encoding an angle of incidence of the active guidance radiation at an entrance pupil onto an active imaging detector. The array also performs an additional function of spatially encoding wavefront tilt deviations emanating from sub-pupils of an exit pupil onto the active imaging detector. A processor processes the electrical signals from the imaging detector in accordance with the respective spatial encodings to generate an active guidance signal and the wavefront error estimate for the primary optical element.