Athermalized Chalcogenide Lens System for Infrared Imaging
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Solution Overview
Problem
Infrared imaging systems face challenges in maintaining focus across varying temperatures due to changes in the index of refraction and size of optical components, leading to thermal defocus and reduced performance.
Innovation Solution
The implementation of a three-lens system with the first and third lens elements made of As40Se60 and the second lens element made of Ge22As20Se58 or Ge28Sb12Se60, which are chalcogenide materials, allows for athermalization by distributing optical power to cancel out changes in focal length and refractive index with temperature changes, along with active focus adjustment and passive mechanical compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single lens element is used in the optical system, then the device complexity is low, but the manufacturing precision and focus stability across temperature variations deteriorate
Solution Approach 1:
The optical system is divided into multiple lens elements (first lens element, second lens element, and third lens element) with different material compositions. Each lens element is segmented to have specific optical powers that collectively compensate for thermal effects, resolving the contradiction between simple structure and precise focus maintenance.
Solution Approach 2:
The patent employs composite chalcogenide materials with specific compositions (As40Se60, Ge22As20Se58, Ge28Sb12Se60) for different lens elements. These composite materials are selected for their complementary thermal expansion coefficients and refractive index characteristics, enabling the system to maintain focus accuracy across temperature variations while managing device complexity through material diversity rather than structural complexity.
2Ease of manufacture
If the lens system uses conventional materials, then the ease of manufacture is high, but the stability of focal length across temperature changes deteriorates
Solution Approach 1:
The patent changes the material parameters (composition and optical properties) of the lens elements to achieve thermal compensation. By selecting chalcogenide materials with specific refractive indices and thermal expansion coefficients, the system maintains focal length stability across temperature ranges from -40°C to +80°C while remaining manufacturable through established optical fabrication processes.
3Manufacturing precision
If the lens system is designed for a narrow temperature range, then the manufacturing precision is easier to achieve, but the adaptability to varying environmental temperatures deteriorates
Solution Approach 1:
The multi-element lens system is designed to perform multiple functions: it provides the primary optical focusing function while simultaneously compensating for thermal effects across a wide temperature range. The combined optical power of the three lens elements is specifically engineered to maintain focus stability from -40°C to +80°C, making the system universally applicable in diverse environmental conditions without sacrificing manufacturing precision.
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 maintains the combined focal length of the lens system within a stable temperature range, ensuring high performance and focus accuracy across temperatures from -40°C to +80°C, critical for infrared imaging applications.
Implementation Method 1
changes in the index of refraction and size of optical components, leading to thermal defocus
Implementation Method 2
changes in the index of refraction and size of optical components
Data Source
AI summary
Techniques for facilitating athermalized lens systems and methods are provided. In one example, an imaging device includes a lens system. The lens system includes a first lens element configured to transmit electromagnetic radiation associated with a scene. The lens system further includes a second lens element configured to receive the electromagnetic radiation from the first lens element and transmit the electromagnetic radiation. The lens system further includes a third lens element configured to receive the electromagnetic radiation from the second lens element and transmit the electromagnetic radiation. The first and third lens element include As40Se60 and the second lens element includes Ge22As20Se58 or Ge28Sb12Se60. The imaging device further includes a detector array including a plurality of detectors. Each detector is configured to receive a portion of the electromagnetic radiation from the lens system and generate an infrared image based on the electromagnetic radiation. Related methods and systems are also provided.