Gradient-Index Flat Light Concentrator Without Sun Tracking
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Solution Overview
Problem
Conventional light concentration devices for photovoltaic cells are bulky, difficult to integrate into domestic applications due to large thickness and complex optical surfaces, with limited acceptance angles and poor performance in diffuse lighting, requiring mechanical sun tracking and being unsuitable for centralized energy production.
Innovation Solution
A light concentration device with a refractive index gradient plate and a diffraction grating, allowing for reduced thickness, increased acceptance angles, and improved performance in diffuse lighting without mechanical sun tracking, featuring a blade with two main faces and a slice between them, where the diffraction grating operates in reflection or semi-reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional Fresnel lenses or parabolic mirrors are used for light concentration, then light concentration capability is achieved, but the device thickness becomes large and bulky
Solution Approach 1:
The patent changes the refractive index parameter by using a gradient refractive index material instead of uniform refractive index materials. This allows light concentration to be achieved within a much thinner profile by continuously varying the refractive index from the front surface to the back surface of the device, enabling the thickness to be reduced to less than one centimeter while maintaining concentration capability
Solution Approach 2:
The patent employs composite optical structures combining gradient refractive index materials with photovoltaic cells and diffraction gratings. This composite approach integrates multiple functions (light concentration, spectrum transformation, and energy conversion) into a single thin-device architecture, eliminating the need for separate bulky optical components
2Area of stationary object
If integrated focusing devices are used to reduce footprint, then surface area is reduced, but optical surfaces become complex and difficult to manufacture
Solution Approach 1:
The patent replaces complex geometric optical surfaces with a gradient refractive index parameter distribution. Instead of manufacturing intricate surface shapes, the invention varies the material's refractive index parameter continuously through the thickness, which can be achieved through controlled material composition gradients during manufacturing
Solution Approach 2:
The patent applies local quality by having different refractive index values at different positions within the device thickness. The front surface has one refractive index value that transitions to a different value at the back surface, creating position-dependent optical properties that simplify the overall surface geometry while maintaining focusing capability
3Power
If conventional light concentrating devices are used, then mechanical sun tracking is required for maximum energy capture, but this increases device complexity and cost
Solution Approach 1:
The patent uses spectrum transformation parameters (converting UV and infrared wavelengths to visible range) to capture energy from a broader angular range and diffuse lighting conditions. This parameter-based approach to spectrum management allows the device to maintain high efficiency without requiring precise mechanical tracking of the sun's position
4Power
If conventional devices are used in diffuse lighting conditions, then performance is mediocre, but the invention maintains effectiveness in cloudy conditions
Solution Approach 1:
The patent transforms the spectral parameters of incoming light by converting UV and infrared radiation into visible light that can be effectively utilized by the photovoltaic cell. This spectral parameter transformation enables the device to capture energy from diffuse lighting and cloudy conditions where direct sunlight is limited, expanding adaptability across different weather conditions
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 device achieves a thickness comparable to the photovoltaic cell, reduces production costs, eliminates the need for mechanical sun tracking, and enhances performance in diffuse lighting conditions, making it suitable for domestic and varied applications.
Implementation Method 1
a refractive index gradient existing between the two main faces
Implementation Method 2
a diffraction grating operating in reflection or in semi-reflection which cooperates with one of the main faces of the blade
Data Source
Figure 1A~2
Figure 3A~3B
Figure 4A~4D
AI summary
The invention relates to a light concentrator that comprises: a plate (1) having two main faces (10, 11), a wafer (13) between the two main faces (10, 11), a refractive index gradient existing between the two main faces (10, 11) and a diffraction grating (2) operating in reflection or in semi-reflection that cooperates with one of the main faces (11) of the plate, that face having the highest refractive index, the main face (10) having the lowest refractive index forming a front face for entry of the light, at least one exit zone (12) for the light being placed on the wafer (13).