MWIR Wide-Angle Lens Mounting for Passive Athermalization
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Solution Overview
Problem
Wide-angle objective lenses for the infrared spectral range face challenges with high weight and low reliability under temperature fluctuations due to complex material selection, and they often lack comprehensive chromatic aberration correction across the MWIR band.
Innovation Solution
A wide-angle objective lens apparatus using a combination of lenses and an infrared detection device held in an aluminium-based optomechanical holding device, achieving achromatic and passive athermalization over a wide temperature range without diffractive optical elements, with a design that includes specific materials and configurations to manage thermal expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex material selection is used to achieve athermalization, then reliability under temperature fluctuations is improved, but weight increases
Solution Approach 1:
The patent changes the material parameter from traditional heavy athermalization materials (like INVAR) to lightweight materials (aluminium alloys, polymers, composites) and compensates by adjusting the geometric parameters (dimensions, shapes) of the holding device to achieve the required thermal compensation effect
Solution Approach 2:
The patent employs composite material structures combining different materials (aluminium alloys with polymers or composites) in the holding device to achieve both lightweight properties and the necessary thermal expansion characteristics for passive athermalization
2Weight of moving object
If aluminium is used as holding material to reduce weight, then weight decreases, but thermal expansion tendency increases
Solution Approach 1:
The patent modifies the geometric parameters (dimensions, shapes, configurations) of the aluminium holding device to compensate for its high thermal expansion coefficient, achieving passive athermalization through carefully designed dimensional relationships that maintain optical alignment across temperature ranges
Solution Approach 2:
The patent deliberately utilizes the thermal expansion properties of aluminium by designing the holding device geometry to exploit controlled expansion and contraction, transforming the harmful effect into a useful mechanism for maintaining optical stability through thermal compensation
3Reliability
If conventional wide-angle objective lenses are designed, then they can detect infrared radiation, but chromatic aberration correction is insufficient across the MWIR band
Solution Approach 1:
The patent adjusts optical parameters (lens curvatures, thicknesses, material selections, spacing) of the wide-angle objective lens to achieve achromatic performance across the entire MWIR band (3.5-5.0 μm), moving beyond conventional narrow-band correction to broad-spectrum achromatization
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 apparatus achieves superior optical performance, compact structure, and simultaneous achromatization and athermalization, with reduced weight and cost, maintaining optical stability across a broad temperature range and minimizing chromatic aberration.
Implementation Method 1
a plurality of lenses (5) and an infrared detection device (6) located one after another coaxially along an optical axis (2)
Implementation Method 2
passively athermalized in a temperature range from −40° C. to 80° C.... the lenses (5) and the infrared detection device (6) are held in an in particular optomechanical holding device (7) and/or in a frame device which comprises aluminium and/or is made of aluminium
Data Source
AI summary
A wide-angle objective lens apparatus, for an infrared spectral range, which—includes a plurality of lens elements and an infrared detector device arranged in succession along an optical axis coaxially in the direction from an object side to an image side, and—is achromatic in the infrared spectral range, in particular from 3.5 μm to 5 μm, and/or is corrected for a chromatic aberration, and—is designed to be passively athermalized in a temperature range of −40° C. to 80° C., wherein—the lens elements and the infrared detector device are held in an optomechanical holding device and/or in a frame device which includes aluminum and/or is formed from aluminum.