Dimpled Light Guide with Bypass Elements for CPV Light Loss
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Solution Overview
Problem
Conventional light guide systems for concentrated photovoltaic (CPV) solar energy face inefficiencies due to interactions with light injection elements, leading to light loss through absorption, scattering, and étendue dilution, which hinder optimal light propagation and concentration.
Innovation Solution
A light guide component with a dimpled structure, featuring light injection elements and bypass elements, promotes total internal reflection and minimizes disruptions by redirecting light around downstream elements, utilizing air prisms, diffraction gratings, or volume diffraction elements, and incorporating a gradient index to enhance light concentration and reduce losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light injection elements are used to concentrate light into the light guide, then light concentration is improved, but light loss through absorption and scattering increases
Solution Approach 1:
The light guide surface is segmented into multiple discrete light injection elements (prisms, gratings, or diffraction elements) distributed across the surface. Each element independently concentrates light from the solar image into the light guide, allowing optimized placement and design of each element to maximize concentration while minimizing overlapping interactions that cause loss.
Solution Approach 2:
The patent introduces an intermediary layer or structure between the light injection elements and the light guide core, such as a reflective coating or index-matched material, that facilitates efficient light coupling while reducing absorption and scattering losses at the interface.
2Quantity of substance
If multiple light injection elements are placed in the light guide, then light collection is improved, but interactions with downstream elements cause étendue dilution and light loss
Solution Approach 1:
Each light injection element is designed with locally optimized properties (different shapes, orientations, or diffraction patterns) tailored to its specific position in the light guide. This ensures that each element effectively directs light into the guide without creating unwanted interactions with downstream elements, maintaining étendue control throughout the light guide length.
Solution Approach 2:
The patent utilizes the third dimension (depth into the light guide) by positioning light injection elements at different locations along the light guide length and using tilted or angled element orientations. This spatial distribution in multiple dimensions reduces overlapping light paths and minimizes étendue dilution from downstream interactions.
3Weight of moving object
If the light guide is made thinner to maintain lightweight form factor, then portability is improved, but light propagation efficiency decreases due to increased interactions with injection elements
Solution Approach 1:
The patent optimizes key parameters including the size, spacing, and orientation of light injection elements relative to the reduced light guide thickness. By adjusting these parameters, the system maintains effective light concentration and propagation efficiency even in thinner guides, balancing weight reduction with performance.
Solution Approach 2:
Light injection elements are designed to concentrate and direct light into the light guide with preliminary optimization for thin-guide geometry. The elements are configured to achieve efficient coupling in the first pass, reducing the need for multiple reflections or interactions that would be more problematic in thinner guides.
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 dimpled light guide system improves light concentration efficiency while maintaining a thin and lightweight form factor, reducing light leakage and increasing the maximum out-coupled light concentration, thereby enhancing the overall performance of CPV systems.
Implementation Method 1
The guide layer has an index of refraction, n1, that is greater than an index of refraction, nmed, of a medium in contact with at least a portion of the top and/or bottom surface in order to promote light propagation by total internal reflection (TIR) within the light guide
Implementation Method 2
Depending upon the tilt angle of the light injection element, the index of refraction of the light guide, and the index of refraction of the external interface of the injection surface, radiation may be totally internally reflected from the face of the light injection element
Data Source
AI summary
A light guide apparatus includes a light guide layer further including light injection elements and respective light bypass elements disposed optically upstream of the light injection elements. The light injection elements and/or the bypass elements can take the form of injection facets (air prisms), surface diffraction elements, volume diffraction elements, and gradient index profiles. A light collection and concentration system comprises a single light guide apparatus, a light-transmitting medium layer disposed immediately adjacent the single light guide apparatus, and a primary light concentrator component disposed adjacent the light-transmitting medium layer, including a plurality of primary concentrator elements each of which is in optical registration with a respective one of the light injection elements of the single light guide apparatus.