Co-aperture Infrared Optical System Aberration Correction
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Solution Overview
Problem
Existing co-aperture broadband infrared optical systems face challenges in design due to limitations in infrared materials, processing, and coating technology, leading to large volume and weight, and thermal defocusing issues in harsh environments, which affect image quality and detection precision.
Innovation Solution
A co-aperture broadband infrared optical system incorporating a Cassegrain lens, multiple lens groups, a spectroscope, and an optical fiber interface, with optimized optical path layout and aberration correction, utilizing a refracting-reflecting structure and multilayer films to achieve broadband imaging and spectral measurement across 2 μm-12 μm, reducing volume and weight while maintaining high transmittance and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a dual-band infrared lens is assembled by 2 separate lenses (mid-wave and long-wave), then the system can achieve dual-band imaging, but the volume and weight become large
Solution Approach 1:
The patent combines mid-wave and long-wave infrared imaging into a single integrated lens structure rather than using two separate lenses. The lens includes multiple lens elements with specific infrared transmission characteristics that enable simultaneous or alternating dual-band imaging, significantly reducing the overall weight and volume while maintaining adaptability for both mid-wave (3-5μm) and long-wave (8-12μm) infrared bands
Solution Approach 2:
The integrated lens is designed to perform multiple functions: it can image in both mid-wave and long-wave infrared bands, and can switch between different bands by adjusting the aperture. The lens elements are specifically designed with materials and coatings that provide universal performance across both spectral ranges, eliminating the need for separate specialized lenses
2Adaptability or versatility
If traditional infrared optical systems are used in harsh temperature environments, then the system can operate in various conditions, but thermal refractive index changes cause thermal defocusing and image quality degradation
Solution Approach 1:
The patent employs optical materials with low thermal coefficients of refractive index and optical path difference. By carefully selecting and combining materials with complementary thermal properties, the system maintains stable optical parameters across a wide temperature range (-40°C to +60°C), preventing thermal defocusing and maintaining image quality without requiring active thermal compensation mechanisms
Solution Approach 2:
The lens incorporates composite material structures including infrared transmission glass, plastic optical materials, and anti-reflective coatings with specific thermal characteristics. These composite structures are designed to compensate for thermal expansion and refractive index changes, ensuring reliable operation in harsh temperature environments while maintaining image quality stability
3Measurement precision
If broadband infrared optical system uses co-aperture design for imaging and spectral measurement, then detection precision and image-spectrum association are improved, but the design complexity increases due to multiple aberration corrections required
Solution Approach 1:
The optical system is segmented into distinct functional modules: an imaging lens for spatial resolution, a spectroscope for spectral decomposition, and separate detection paths for imaging and spectral measurement. This modular segmentation allows each component to be optimized independently for its specific function while maintaining co-aperture alignment, reducing overall design complexity compared to a fully integrated single-component system
Solution Approach 2:
The spectroscope acts as an intermediary component that receives light from the common aperture and separates it into spectral components. This intermediary structure enables both imaging and spectral measurement functions to share the same aperture and optical path up to the spectroscope, achieving high image-spectrum association precision while keeping the design manageable through clear functional separation
4Ease of manufacture
If infrared optical system is designed with limited materials and processing capabilities, then manufacturing is simplified, but achieving broadband co-aperture with aberration correction becomes extremely challenging
Solution Approach 1:
The patent specifies precise parameter ranges for lens elements including focal lengths, curvatures, thicknesses, and material properties that balance manufacturing feasibility with aberration correction requirements. By optimizing these parameters within practical manufacturing constraints, the system achieves broadband co-aperture performance with acceptable precision using available infrared materials and conventional processing techniques
Solution Approach 2:
Different regions of the optical system use different material properties and design approaches tailored to local requirements. The imaging portion uses materials optimized for spatial resolution, while the spectral portion uses materials optimized for spectral transmission. Coatings and surface treatments are applied locally to specific lens elements to correct aberrations in critical areas without requiring uniform high-precision processing across all components
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 compact size, high integration, and stable image quality across a wide spectral range, with improved transmittance and reduced thermal defocusing, enabling precise LWIR imaging and broadband spectrum measurement, suitable for harsh environments and various applications.
Implementation Method 1
a Cassegrain lens, a first lens group, a spectroscope, a second lens group
Implementation Method 2
a spectroscope, a second lens group, an imaging interface
Implementation Method 3
utilizing a refracting-reflecting structure and multilayer films to achieve broadband imaging
Data Source
AI summary
The present invention discloses a co-aperture broadband infrared optical system, belonging to the field of infrared optical system. The system realizes long wave infrared (LWIR) imaging and broadband infrared spectrum measurement, and solves the problems of limited optical path layout, large volume and high cost of an optical system. The present invention includes a Cassegrain lens, a spectroscope, a reflector, several lens groups, an FPA interface and an optical fiber interface. Light (2 μm˜12 μm) is incident to the Cassegrain lens to be focused, then is split by the spectroscope, where 50% of the LWIR light (8 μm˜10 μm) passes through the lens group for aberration correction, and the image plane is focused again at the imaging interface. The other 50% of the LWIR light (8 μm˜10 μm) and the infrared reflected light (2 μm˜8 μm and 10 μm˜12 μm) pass through the lens group, and are reflected by the reflector, then focused at the optical fiber interface. The present invention is compact in overall structure and convenient and flexible to use, has relatively low cost, and can be integrated into an image-spectrum associated detection device to implement automatic detection and tracking, which can be widely used in civil and military fields such as environmental monitoring and infrared guidance.