MWIR Continuous Zoom Optical System Narcissus Effect Control
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Solution Overview
Problem
Infrared optical systems with limited field-of-view configurations experience interrupted output images during switching, and high magnification MWIR continuous zoom systems face challenges with the Narcissus effect due to temperature differences, which affect image quality and are difficult to design for compactness and cost-effectiveness.
Innovation Solution
A high magnification MWIR continuous zoom optical system with a hybrid aspheric-diffractive surface design, comprising multiple optical groups including an extender, fixed, moving, and relay groups, optimized for minimal Narcissus effect and compactness, using materials like Germanium, Zinc Selenide, and Silicon, allowing continuous zoom with a 20× magnification ratio and maintaining image quality across field-of-view configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high magnification MWIR continuous zoom system is designed with a cooled detector, then the sensitivity and target detection range are improved, but the Narcissus effect occurs due to temperature difference between the system housing and detector
Solution Approach 1:
The optical system is divided into multiple groups (first zoom group, second zoom group, relay group) with distinct functions. The first zoom group handles focal length adjustment while the second zoom group and relay group work together to control the Narcissus effect through specific movement patterns and optical path design.
Solution Approach 2:
The second zoom group acts as an intermediary between the first zoom group and the relay group, specifically designed to counteract the Narcissus effect by adjusting optical paths and distributing reflected energy away from the detector through its unique lens configuration and movement characteristics.
2Adaptability or versatility
If the optical system uses multiple optical components to achieve high magnification ratio, then the zoom capability is improved, but the system size and complexity increase
Solution Approach 1:
The patent combines multiple zoom functions into two coordinated zoom groups rather than using separate mechanisms for each function. The relay group is integrated with the second zoom group, allowing them to work together in a unified structure that achieves high magnification ratio while controlling overall system complexity.
Solution Approach 2:
The relay group serves multiple functions: it acts as part of the zoom mechanism for achieving high magnification ratio, simultaneously functions to control the Narcissus effect, and provides image relay to the detector. This multi-functionality reduces the need for separate dedicated components.
3Adaptability or versatility
If the optical components travel to designated positions during configuration switching, then the field-of-view switching is achieved, but the output image quality deteriorates during transition
Solution Approach 1:
The patent implements continuous zoom capability where the optical groups move smoothly and continuously rather than in discrete steps or interrupted motions. This continuous movement ensures that the optical system maintains proper focus and image quality throughout the entire transition process between different field-of-view configurations.
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 achieves crisp target images with minimal Narcissus effect and maintains high image quality during focal length transitions, ensuring a compact, cost-effective, and efficient optical system suitable for long-range surveillance.
Implementation Method 1
the optical relay group, which focuses the incoming light from close objects
Implementation Method 2
application of hybrid aspheric-diffractive surfaces
Implementation Method 3
application of hybrid aspheric-diffractive surfaces
Implementation Method 4
The low operating temperature will allow for better sensitivity which helps when the optical system focuses into distant objects from more than 10 kilometers away. However, the cooled detector also comes with a problem, which is the Narcissus effect caused by high temperature difference between the system housing and the detector. This temperature difference is reflected at the optical surfaces within the system and turns back to the detector
Data Source
AI summary
A high magnification MWIR continuous zoom optical system is described herein that consists of the following components: a front detachable extender group, a fixed group for focusing incoming radiation, three moving groups for zooming and generating an intermediate image and a relay group. The mentioned optical system has the ability to work with MWIR radiation (3-5 μm) and generate a thermal image from the gathered radiation. The system also has the ability to zoom continuously in a wide variable focal length range with a high magnification ratio of 20×. With the use of a cooled detector, the combined system allows its user to be able to receive high quality thermal images in all FOV configurations.