Optical Filter with Segmented Channels for Uniform Sun Image
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Solution Overview
Problem
Current lighting units simulating natural sunlight fail to produce a spatially uniform luminance profile and a circular sun image with sharp contrast to the sky, due to issues with secondary images, high losses, and unwanted patterns from existing optical filters.
Innovation Solution
An optical filter design featuring parallel, elongated channels with a central core and claddings, where the first optically absorbing material reduces light passage between channels and enhances transmission efficiency, achieving a sharp cut-off angle and minimizing secondary images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a tandem mixer optical filter is used to produce uniform luminance and constant angular luminance profile, then the image of the sun appears uniform and circular, but secondary images are produced and construction complexity increases
Solution Approach 1:
The optical filter is divided into multiple independent channels (first channel, second channel, third channel, fourth channel) with different refractive indices. Each channel acts as an independent light-guiding element, allowing the system to achieve complex angular luminance control through simple parallel structures rather than complex integrated designs.
Solution Approach 2:
Different regions of the optical filter have different refractive indices (first region with first refractive index, second region with second refractive index, etc.). This local differentiation allows each channel to control light propagation independently, enabling precise control over the angular luminance profile without requiring complex overall structure.
2Object-generated harmful factors
If absorbing material is placed between channels to reduce light passage, then unwanted light transmission is reduced, but light transmission efficiency decreases
Solution Approach 1:
Channels with intermediate refractive indices (second channel with second refractive index between first and third, fourth channel with fourth refractive index between first and fifth) act as optical mediators. These intermediate channels guide light that would otherwise be lost, converting harmful light leakage into useful light transmission and reducing the need for absorbing materials.
Solution Approach 2:
The refractive indices of different channels are specifically designed to vary (first refractive index > second refractive index > third refractive index, etc.). This parameter variation allows precise control over light propagation angles, enabling the system to direct light where needed without requiring energy-lossy absorbing materials.
3Ease of manufacture
If square or rectangular lenses are used to maximize coverage, then construction simplicity is achieved, but the sun image shape becomes non-circular
Solution Approach 1:
The optical filter uses multiple independent channels with different refractive indices arranged in a grid pattern. This segmentation allows the system to achieve circular sun images through the combined effect of simple parallel channels rather than requiring complex curved lens elements.
Solution Approach 2:
The optical filter combines multiple channels with different refractive indices (first channel with first refractive index, second channel with second refractive index, etc.) to create a composite optical system. This composite structure enables the system to achieve circular image shapes while maintaining construction simplicity through the use of straightforward parallel channel geometries.
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 provides a lighting unit capable of generating a circular sun image with well-defined contours and preserved sky contrast, eliminating the need for low-angle diffuser filters and reducing costs through improved transmission efficiency and material usage.
Implementation Method 1
Each channel has a first refractive index and a second refractive index, the first refractive index being greater than the second refractive index. The channels are configured to produce an angular luminance profile characterised by a cut-off angle.
Implementation Method 2
Each channel has a first refractive index and a second refractive index... the first refractive index being greater than the second refractive index
Implementation Method 3
said channels being surrounded by a second optically absorbing material, wherein said second optically absorbing material is configured to reduce the passage of light through said channels
Data Source
AI summary
An optical filter is described comprising a first surface and a second surface which are substantially flat and parallel to each other; a plurality of optically transparent channels, parallel to each other, and made of at least one solid material, each channel having: an elongated conformation along a longitudinal axis and extending between said first surface and said second surface; and a respective side surface; each channel comprising at least one central core having a first refractive index; a first cladding which wraps the outer side surface of said central core and having a second refractive index lower than said first refractive index; a first optically absorbing material interposed between the side surface of adjacent channels and configured to reduce the passage of light through adjacent channels; wherein each channel has a length L along said longitudinal axis which satisfies the following relationship L<AL0: where formula (I) ηa is the value of said first refractive index, R is an average channel radius of the plurality of channels, θ0 is a cut-off angle of the filter and A is a constant equal to 5.