Wideband Diffraction Limited Optical Receiver Using Composite Doublet Lens
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Solution Overview
Problem
Achieving diffraction limited performance over a wide band of wavelengths, particularly in the infrared band, is challenging due to limitations in available materials for correcting chromatic aberrations across various wavelengths.
Innovation Solution
A doublet lens assembly is constructed using lenses made from materials with different dispersive properties, with a diffraction grating applied to one or more surfaces, positioned with an air gap to enhance chromatic correction and achieve diffraction limited performance across a wide wavelength band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional lens materials are used to correct chromatic aberrations, then performance is improved over a narrow wavelength range, but diffraction limited performance cannot be achieved over a wide wavelength band including infrared
Solution Approach 1:
The patent combines multiple lens materials (germanium and zinc selenide) with different dispersive properties in a doublet configuration to correct chromatic aberrations across a wide infrared wavelength band. This composite approach allows simultaneous optimization for different wavelengths that cannot be achieved with single materials.
Solution Approach 2:
A diffractive optical element is introduced as an intermediary component between the lens elements to provide additional chromatic correction. This element mediates the wavelength-dependent phase errors that remain after refractive correction, enabling diffraction limited performance across the extended wavelength range.
2Reliability
If available infrared materials are used for lens construction, then transmission properties are maintained, but chromatic aberration correction is insufficient for wideband applications
Solution Approach 1:
The patent uses composite lens construction with germanium and zinc selenide materials, each selected for specific transmission windows in the infrared spectrum. The combination maintains high transmission across the 8-12 micrometer band while the different dispersive properties of each material enable chromatic aberration correction.
Solution Approach 2:
The patent changes the refractive index parameter distribution across the lens system by using materials with different dispersion characteristics. This parameter variation enables the doublet configuration to correct chromatic aberrations that cannot be corrected with uniform material properties.
3Measurement precision
If a diffraction grating is applied to lens surfaces, then chromatic correction is enhanced for wideband performance, but manufacturing complexity increases
Solution Approach 1:
The diffractive optical element is merged with the refractive lens surfaces to create a hybrid element. This combining of diffractive and refractive functions in a single component reduces the total number of elements needed while achieving superior chromatic correction across the wide wavelength band.
Solution Approach 2:
The diffractive structure is fabricated as an integrated feature on the lens surface using precision molding or etching techniques. This composite approach combines the refractive power of the lens material with the diffractive phase modulation in a single manufacturable component.
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 solution effectively minimizes chromatic aberrations, providing diffraction limited performance over a wide wavelength range, as demonstrated by reduced RMS refraction error and achromatic response, enabling applications such as forward-looking infrared sensors.
Implementation Method 1
A diffraction grating is applied to one of the first and second surfaces of the first and second lenses
Implementation Method 2
A diffraction grating is applied to one of the first and second surfaces of the first and second lenses
Implementation Method 3
A first lens is constructed from a first material and has a first surface and a second surface. A second lens is constructed from a second material
Implementation Method 4
lenses made from materials with different dispersive properties
Data Source
AI summary
Systems and methods are provided for providing wideband diffraction limited performance in an optical receiver. A first lens is constructed from a first material and has a first surface and a second surface. A second lens is constructed from a second material and having a first surface and a second surface. The second lens is positioned such that a first surface of the second lens faces a second surface of the first lens across a gap of air. A diffraction grating is applied to one of the first and second surfaces of the first and second lenses.