Optical System Thermal Boresight Correction via Detector Radiation Sources
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Solution Overview
Problem
Optical systems face challenges in accurately compensating for thermally induced changes in boresight and effective focal length without requiring accurate and constant temperature measurements or complex calibration processes, especially in varying environmental conditions such as those encountered in aerospace applications.
Innovation Solution
The method involves attaching radiation emitting sources to the optical system's support frame or first optical element, measuring initial and shifted image locations on a detector at standard and varying temperatures, calculating shifts, and correcting boresight and focal length using these measurements, without needing temperature data. This is achieved by activating radiation sources, measuring image shifts, and applying corrections through a processor with adapted software.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors and electro-mechanical assemblies are used to compensate for focal length drift, then compensation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts the temperature sensing function from a separate sensor and integrates it into the detector element itself. The detector element directly measures its own operating temperature, eliminating the need for separate temperature sensors and reducing device complexity while maintaining compensation accuracy.
Solution Approach 2:
The detector element serves multiple functions: it detects optical signals for imaging and simultaneously measures its own operating temperature. This multi-functionality reduces the number of components needed and simplifies the overall system structure while enabling accurate thermal compensation.
2Measurement precision
If multiple lens and mirror arrays are used to compensate for focal length drift, then compensation accuracy is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces complex mechanical compensation systems (multiple lenses and mirrors) with an electronic/software-based solution. The processor unit uses temperature data from the detector element to calculate and apply compensation factors to the image data, eliminating the need for additional optical components and simplifying manufacturing.
3Measurement precision
If temperature sensors are integrated into the optical system, then compensation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the temperature sensing function with the detector element by providing means for the detector element to directly sense its own operating temperature. This integration eliminates separate temperature sensor components and reduces device complexity while improving temperature measurement accuracy for compensation purposes.
4Device complexity
If conventional electronic compensation methods are used, then device complexity is reduced, but measurement precision of temperature changes decreases
Solution Approach 1:
The patent implements local temperature measurement by having each detector element sense its own operating temperature rather than using a single average temperature measurement. This localized measurement approach provides higher temperature measurement precision for compensation while maintaining relatively simple device architecture through software-based processing.
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 allows for accurate compensation of thermally induced boresight and focal length changes without relying on temperature measurements, simplifying calibration and enhancing the system's ability to maintain image accuracy across temperature variations, applicable to various electromagnetic wavelength ranges.
Implementation Method 1
providing a plurality of radiation emitting sources
Implementation Method 2
The cumulative effect of the thermally induced changes for each of the individual optical and mechanical elements is to cause a change in the effective focal length of the system and a shifting of the image on the detector
Implementation Method 3
measuring in a selected coordinate system the shifted locations of the center and/or the new size of the images of the radiation emitting sources that are formed on the detector
Data Source
AI summary
A method and system are for measuring and correcting shifts in the boresight, effective focal length, and focus of an optical system that are caused by temperature variations. The method can be used for systems which can be expected to operate in situations where the temperature variations are large, e.g. a FLIR system of a fighter plane, and also where the temperature variations can be very small however high accuracy is needed. The invention is based on placing radiation emitting sources before and as close as possible to the first optical element of the optical system and measuring the thermally induced shifts of the locations of the images of the radiation emitting sources on the surface of the detector of the optical system.