Monolithic Lens Reflector for Wide-Angle IR Sensors
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Solution Overview
Problem
Conventional wide-angle infrared sensor designs face challenges in achieving compact size and high image quality due to optical asymmetry and the need for aberration corrections, which increases manufacturing costs and complexity.
Innovation Solution
A monolithic body with a compound optical surface that combines a transmissive lens element and a reflective coating, formed using diamond point turning, is used to create a compact optical element assembly that includes a dewar with a coldshield and uncooled optical elements, reducing the need for separate reflector and lens components and improving alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wide-angle lens systems with dewar and coldshield technology are used, then infrared sensitivity is maintained, but the system size increases and manufacturing complexity increases due to optical asymmetry and aberration corrections
Solution Approach 1:
The patent combines the coldshield and lens elements into a single monolithic optical component. The coldshield serves dual functions as both a thermal shield and an optical element, eliminating the need for separate lens components. This integration reduces the overall system volume while maintaining infrared sensitivity through the coldshield's optical properties.
Solution Approach 2:
The coldshield is designed to perform multiple functions simultaneously: thermal shielding, optical focusing, and aperture definition. By making the coldshield optically active with aspheric surfaces, it becomes a multi-functional component that replaces both the traditional coldshield and lens system, thereby reducing system size and complexity.
2Manufacturing precision
If conventional wide-angle lens systems with multiple elements are used, then image quality is maintained, but the device complexity and manufacturing cost increase
Solution Approach 1:
Multiple optical functions previously requiring separate lens elements are consolidated into the monolithic coldshield component. The coldshield incorporates aspheric surfaces that provide aberration correction, focusing, and field flattening that would traditionally require multiple discrete optical elements, thereby reducing device complexity while maintaining image quality.
Solution Approach 2:
The coldshield is fabricated from materials with appropriate optical and thermal properties for infrared wavelengths. The use of specialized materials with tailored refractive indices and thermal characteristics enables the coldshield to perform both thermal and optical functions effectively in a single component.
3Reliability
If the aperture stop is located within the dewar as a coldstop, then infrared sensitivity is maintained, but optical asymmetry complicates lens design and limits image quality
Solution Approach 1:
The patent embraces and optimizes the inherent optical asymmetry created by the coldstop location within the dewar. Rather than attempting to create a symmetric design, the coldshield incorporates asymmetric aspheric surfaces specifically tailored to the asymmetric optical path, enabling high-quality imaging despite the asymmetric stop position.
Solution Approach 2:
The coldshield features locally optimized aspheric surfaces with different curvatures and profiles in different regions. The optical surface is designed with varying local properties to correct for the asymmetric light paths from different field angles, maintaining high image quality across the entire field of view despite the asymmetric coldstop location.
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 solution enables a more compact and cost-effective wide-angle infrared sensor with improved image quality and reduced scatter, achieving accurate positioning and alignment of reflective and refractive surfaces while maintaining infrared sensitivity.
Implementation Method 1
a reflector disposed about said lens element that is reflective to the light
Implementation Method 2
a centrally located lens element that is transmissive to light having wavelengths of interest, such as infrared radiation (IR)
Data Source
AI summary
A monolithic body (31) has a compound optical surface that defines a centrally located lens element (31B) that is transmissive to light having wavelengths of interest, such as infrared radiation (IR), and a reflector (31B) disposed about the lens element that is reflective to the light. The monolithic body is comprised of a material selected for fabricating a refractive lens element. The compound optical surface has a centrally located portion defining the lens element surrounded by a generally curved surface region having a reflective coating that defines the reflector. The centrally located portion may be coated with an anti-reflection coating. The compound optical surface is preferably formed in one operation, such as one that uses a diamond point turning operation.