Electronic Reticle Correction for Variable-Magnification Boresight Errors
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Solution Overview
Problem
Boresight errors occur in variable magnification optical systems due to deviations in the orientation of lenses, particularly when using larger magnifications for sighting remote targets, which affect the alignment between the gun-barrel and pointing-device orientations, especially when the reticle is positioned behind the magnification changer.
Innovation Solution
A system that includes a focusing lens to create an image at a focal plane, a magnification changer with an optomechanical drive system, a light source emitting a pilot beam, a position sensitive photodetector, and a microdisplay to correct boresight errors by adjusting the electronic reticle position based on the pilot beam's position relative to the photodetector, using look-up tables for precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the reticle is positioned behind the magnification changer (second focal plane), then the reticle size remains constant when magnification varies and relay correction for aberrations is not needed, but boresight errors are introduced due to lens movement
Solution Approach 1:
A feedback system is implemented using a pilot beam source that passes through the magnification changer to a position-sensitive photodetector. The photodetector detects beam position shifts caused by lens movement, and this information is fed back to an electronic reticle positioning system that automatically compensates for the detected boresight errors, thereby maintaining alignment precision while allowing the reticle to remain in the second focal plane
Solution Approach 2:
The patent replaces mechanical reticle adjustment mechanisms with an electronic reticle positioning system. Instead of physically moving the reticle to compensate for boresight errors, an electronic display (such as an LCD or OLED) dynamically adjusts the reticle position based on feedback from the photodetector, eliminating the need for mechanical tracking components
2Manufacturing precision
If the reticle is positioned in front of the magnification changer (first focal plane), then boresight alignment is maintained, but the reticle size changes with magnification and relay correction for aberrations is required
Solution Approach 1:
The patent replaces mechanical reticle adjustment mechanisms with an electronic reticle positioning system. Instead of physically moving the reticle to compensate for boresight errors, an electronic display (such as an LCD or OLED) dynamically adjusts the reticle position based on feedback from the photodetector, eliminating the need for mechanical tracking components
3Manufacturing precision
If mechanical tracking components are added to correct boresight errors, then alignment precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces mechanical reticle adjustment mechanisms with an electronic reticle positioning system. Instead of physically moving the reticle to compensate for boresight errors, an electronic display (such as an LCD or OLED) dynamically adjusts the reticle position based on feedback from the photodetector, eliminating the need for mechanical tracking components
Solution Approach 2:
The patent introduces a pilot beam as an intermediary element to detect boresight errors. The pilot beam passes through the magnification changer and its position shifts provide information about lens movement, serving as a mediator between the optical system and the electronic reticle positioning system without requiring direct mechanical coupling
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 system effectively corrects boresight errors by accurately positioning the electronic reticle, allowing for precise aiming even when the reticle is placed in the second focal plane, maintaining aiming accuracy and reducing mechanical tracking errors.
Implementation Method 1
a position sensitive photodetector configured to receive the pilot beam exiting the magnification changer
Implementation Method 2
a focusing lens to receive light along an optical axis of the variable magnification optical system, with the focusing lens configured to create an image of a target at a focal plane
Implementation Method 3
a light source configured to emit a pilot beam into the magnification changer
Data Source
AI summary
A variable magnification optical system with boresight error correction includes a focusing lens to receive light along an optical axis of the variable magnification optical system, with the focusing lens configured to create an image of a target at a focal plane. The system includes a magnification changer disposed along the optical axis, with the magnification changer including an optomechanical drive system to adjust an optical magnification setting of one or more zoom lenses. The system also includes a light source configured to emit a pilot beam into the magnification changer. The system includes a position sensitive photodetector configured to receive the pilot beam exiting the magnification changer. The system further includes a microdisplay optically conjugate to the focal plane, with the microdisplay configured to impose an image of an electronic reticle on the focal plane based on the position of the pilot beam relative to the position sensitive photodetector.