Diffractive Axilenses for Achromatic Multispectral Imaging
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Solution Overview
Problem
Current diffractive optical elements face challenges such as high manufacturing costs, optical losses, and limited spectral discrimination, which hinder the development of highly integrated optical devices for multispectral imaging and sensing applications.
Innovation Solution
The development of scalable, polarization-insensitive, multi-level diffractive optical elements with phase-modulated axilenses that focus incident radiation at prescribed locations on a detection plane, allowing for achromatic focal planes and efficient broadband operation, using a conventional 4-level lithography process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional microlens solutions are used, then optical concentration for focal plane arrays is achieved, but optical losses and high manufacturing costs occur
Solution Approach 1:
The patent replaces conventional microlens optical systems with diffractive optical elements (DOEs) that use diffraction rather than refraction to achieve optical concentration. This substitution eliminates material absorption losses inherent in microlenses and enables high efficiency broadband operation across multiple wavelengths.
Solution Approach 2:
The patent employs multi-level phase modulation in the diffractive optical element to control the diffraction of incident radiation. By varying the phase depth and pattern geometry, the DOE achieves prescribed focal locations for multiple wavelengths simultaneously, maintaining high optical concentration efficiency while avoiding the optical losses of conventional approaches.
2Use of energy by moving object
If conventional microlens solutions are used, then optical concentration is achieved, but high manufacturing costs occur
Solution Approach 1:
The patent replaces expensive precision-machined microlens arrays with diffractive optical elements that can be fabricated using standard semiconductor lithography techniques. This substitution dramatically reduces manufacturing costs while maintaining optical concentration performance and enabling large-scale production.
Solution Approach 2:
The diffractive optical element is designed to perform multiple functions: optical concentration, spectral discrimination, and achromatic focusing across broadband wavelengths. This multi-functionality eliminates the need for separate optical components, reducing overall system complexity and manufacturing cost.
3Measurement precision
If conventional optical elements are used, then focusing is achieved, but spectral discrimination is limited
Solution Approach 1:
The diffractive optical element simultaneously provides optical concentration and spectral discrimination in a single component. By designing the phase pattern to create wavelength-dependent focal locations, the DOE separates different wavelengths spatially on the detector plane without requiring additional spectral filtering elements, thereby maintaining simple system architecture while achieving high spectral discrimination.
Solution Approach 2:
The patent utilizes the spatial dimension on the detector plane to encode spectral information. Different wavelengths are focused to different lateral positions rather than requiring temporal or spectral filtering, enabling spectral discrimination through spatial separation while maintaining a compact, single-element system.
4Measurement precision
If diffractive optical elements with thickness greater than wavelength are used, then focusing capability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent employs multi-level phase modulation with discrete height levels in the diffractive optical element. This approach achieves precise focusing control through phase discontinuities at sub-wavelength thickness, eliminating the need for thick optical elements while maintaining diffraction efficiency and focusing precision through optimized phase step heights.
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
These elements achieve high focusing efficiency over a broad spectral band with programmable depth of focus and wavelength selectivity, enabling compact, scalable, and cost-effective integration in multispectral imaging and sensing systems.
Implementation Method 1
The pattern is configured to focus an incident radiation, received at one of the top surface or the bottom surface of the substrate, at one or more prescribed focal locations on a detection plane. The one or more prescribed focal locations on the detection plane changes in proportion to a wavelength of the incident radiation.
Data Source
AI summary
An optical element includes a substrate and a pattern. The substrate has a top surface and a bottom surface. The pattern is provided on the top surface. The pattern includes multiple levels such that a thickness of the pattern is less than a design wavelength. The pattern is configured to focus an incident radiation, received at one of the top surface or the bottom surface of the substrate, at one or more prescribed focal locations on a detection plane. The one or more prescribed focal locations on the detection plane changes in proportion to a wavelength of the incident radiation. The detection plane is an achromatic focal plane when the incident radiation includes multiple wavelengths.