Illumination Homogenizing Optical Element for Uniform Lighting
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Solution Overview
Problem
Conventional methods for correcting non-uniform illumination in digital photography, such as using neutral density filters or frosted filters, face issues like wavelength dependency and inaccuracies in transmittance, and do not effectively utilize the optical characteristics of the illumination system.
Innovation Solution
An optical element with refractive structures, such as prism-like grooves or protrusions, that control light transmittance by refracting unwanted light out of the path, providing a transmittance distribution that corrects illumination non-uniformity while being easy to manufacture and cost-effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a neutral density filter is used to correct non-uniform illumination, then illumination uniformity is improved, but wavelength characteristics are affected and color accuracy deteriorates
Solution Approach 1:
The patent applies local quality by creating a filter with spatially varying transmittance properties. Different regions of the filter have different transmittance values, allowing selective correction of illumination non-uniformity at specific locations while maintaining wavelength independence. This is achieved through precise control of the transmittance distribution across the filter surface, enabling uniform illumination without compromising color accuracy.
2Illumination intensity
If a frosted filter is used to correct non-uniform illumination, then illumination uniformity is improved, but manufacturing precision deteriorates due to inability to achieve exact calculated transmittance
Solution Approach 1:
The patent replaces the mechanical scattering mechanism of frosted filters with a precise transmittance control mechanism. Instead of relying on physical frosted surfaces that are difficult to manufacture with precision, the invention uses a filter design where the transmittance distribution is precisely controlled through manufacturing processes that can achieve the calculated values. This substitution enables exact transmittance control while maintaining illumination uniformity.
3Illumination intensity
If an integrator such as a fly-eye lens is used to divide light flux, then illumination uniformity is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the illumination uniformity correction function from complex optical systems like fly-eye lenses and integrates it into a single filter element. By taking out the essential function of dividing and redistributing light flux and implementing it through a filter with specific transmittance distribution, the invention simplifies the overall optical system while maintaining illumination uniformity.
4Illumination intensity
If an optical element with inverse transmittance distribution is used to correct illumination, then illumination uniformity is improved, but the element does not truly utilize illumination optical system characteristics
Solution Approach 1:
The patent applies feedback by designing the filter transmittance distribution based on the actual illumination characteristics and optical system properties. The transmittance values are calculated considering the specific illumination optical system characteristics, creating a feedback loop where the filter design responds to and adapts with the illumination system's actual behavior, rather than using a generic inverse distribution.
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 optical element achieves uniform illumination by refracting unwanted light, reducing diffraction effects and ensuring accurate color reproduction, while being simpler and less costly to produce than previous solutions.
Implementation Method 1
refractive structures on at least one optical surface... that control light transmittance by refracting unwanted light out of the path
Data Source
AI summary
An illumination homogenizing optical element is disclosed that includes at least one optical surface having a plurality of refractive structures formed as either grooves or protrusions that, individually, are wider than the wavelength of light incident onto said illumination homogenizing optical element. At least part of the light incident onto the illumination homogenizing optical element is removed from the optical path by refraction of said light so as to provide even illumination on an illuminated surface. The illumination homogenizing optical element is advantageous over prior art illumination homogenizing optical elements in that it is easy and inexpensive to manufacture while providing sufficient optical performance.