Fresnel Lens Chromatic Correction via Digital Deconvolution
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Solution Overview
Problem
Fresnel lenses suffer from chromatic aberration, which complicates their use in applications requiring imaging over a large bandwidth, as conventional correction methods involve adding heavy and complex optical elements.
Innovation Solution
The use of multiple optical detectors positioned at specific distances from the Fresnel lens to capture light of different wavelengths, followed by signal processing through deconvolution to generate image data representative of images at a specified tuned wavelength, eliminating the need for additional optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Schupmann corrector (reverse Fresnel lens with additional convergent lenses) is used to correct chromatic aberration, then chromatic correction is achieved, but device complexity and weight increase due to adding two additional optical elements
Solution Approach 1:
The patent extracts the chromatic correction function from the optical domain and relocates it to the digital signal processing domain. Instead of using additional optical elements (reverse Fresnel lens and convergent lenses) to correct chromatic aberration, the invention captures wavelength-separated signals with multiple detectors and performs digital deconvolution to reconstruct images at different wavelengths, thereby eliminating the need for complex optical correction elements.
Solution Approach 2:
The patent replaces the mechanical/optical correction system (Schupmann corrector with multiple lenses) with a digital signal processing system. The physical optical elements used for chromatic correction are substituted by computational algorithms (deconvolution) that process detector signals to achieve the same chromatic correction effect, reducing mechanical complexity and weight.
2Reliability
If a Schupmann corrector is used to correct chromatic aberration, then chromatic correction is achieved, but weight increases due to additional optical elements
Solution Approach 1:
The patent extracts the chromatic correction function from the physical optical system and transfers it to the digital processing domain. By removing the reverse Fresnel lens and convergent lenses from the optical path, the system eliminates their weight while maintaining chromatic correction capability through digital deconvolution of detector signals.
Solution Approach 2:
The patent substitutes heavy optical elements (lenses and correctors) with lightweight digital signal processing. The mass of additional optical components required for chromatic correction is replaced by computational algorithms running on detectors and processors, achieving weight reduction while preserving the chromatic correction function.
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 approach effectively corrects chromatic aberration in Fresnel lenses without adding weight or optical complexity, enabling color-corrected image data and sub-band image detection without the need for extra lenses.
Implementation Method 1
each wavelength of light is refracted to a different focal point on the optical axis of the lens
Implementation Method 2
disposing multiple optical detectors at selected distances from the lens, whereby light of different bands of wavelength focus on different ones of the multiple detectors
Implementation Method 3
processing signals generated by the multiple optical detectors to generate, by deconvolution, output signals representative of images at a specified tuned wavelength for each detector
Data Source
AI summary
Chromatic correction of a Fresnel lens is effected by collecting data at multiple detectors arrayed along the optical axis of the lens and then digitally processing data from each detector to obtain multiple sets of image data corresponding to selected tuned wavelengths associated with the multiple detectors, or to obtain composite multi-color image data. Digital processing includes deconvolving data from each detector with a point spread function (PSF) associated with the tuned wavelength of the detector, and thereby enhancing the image derived from the detector. Two possible techniques are also disclosed for deriving sub-band signal data having a wavelength that falls between the tuned wavelengths of adjacent detectors.