Zoom Lens Light Distribution Correction via Polynomial Data
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Solution Overview
Problem
Existing camera systems face challenges in maintaining uniform light distribution across the image plane, particularly due to changes in zoom, focus, and aperture, which lead to peripheral light attenuation and increased spherical aberration.
Innovation Solution
A zoom lens unit with a storage medium that stores correction data to compensate for light amount variations in image data, using an n-th order polynomial expression to approximate correction amounts based on image height, zoom, focus, and iris states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the effective diameter of the lens is increased to cover all light beam paths during operation, then the light amount distribution is improved, but the lens apparatus size and weight increase and spherical aberration worsens
Solution Approach 1:
The patent changes the parameter of effective diameter dynamically by moving the aperture stop to different positions along the optical axis corresponding to different focal lengths. This allows the lens to maintain appropriate light beam coverage without requiring a constantly large effective diameter, thus reducing size while maintaining illumination quality.
2Illumination intensity
If the effective diameter of the lens is increased to cover all light beam paths during operation, then the light amount distribution is improved, but spherical aberration increases and becomes difficult to correct
Solution Approach 1:
The patent dynamically adjusts the effective diameter parameter by positioning the aperture stop at different locations along the optical axis for different focal lengths. This prevents excessive spherical aberration that would occur with a constantly large effective diameter while ensuring adequate light beam coverage for proper illumination distribution.
3Quantity of substance
If a low-order polynomial expression is used for correction, then the data amount is reduced, but the approximation error increases when light amount change is steep
Solution Approach 1:
The patent dynamically selects the order of the polynomial expression for correction based on the actual light amount distribution characteristics. When light amount changes are steep, higher-order polynomials are used for accurate correction. When changes are gradual, lower-order polynomials suffice, reducing data amount. This dynamic adaptation optimizes both data efficiency and correction accuracy.
Data Source
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AI summary
Provided is a storage medium which stores correction data for obtaining a correction amount for correcting image data, obtained from an image formed by a lens apparatus, with respect to a distribution of a light amount in the image, wherein the correction data includes a coefficient of an n-th order polynomial (where n is a non-negative integer) for an image height h, which corresponds to a state of the lens apparatus. The coefficient satisfies a first conditional expression −0.15≤dDʹh−dDlensh≤1.98, where dDlens(h) represents a change amount of the light amount at the image height h per an increase amount dh of the image height h, and dD'(h) represents a change amount of an inverse of a value of the n-th order polynomial at the image height h per the increase amount dh.