Blazed Diffraction Gratings for Spectral Solar Control
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Solution Overview
Problem
Conventional window technologies fail to efficiently control solar radiation based on its wavelength, leading to increased cooling and heating costs, as they either block daylight or allow heat, and existing smart windows lack the ability to dynamically manage infrared and visible radiation separately.
Innovation Solution
The use of blazed diffraction gratings in smart windows, positioned in series with opposite blaze directions, to effectively separate and control visible and near-infrared radiation, allowing for dynamic control of solar radiation transmission and rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional mechanical methods (awnings, blinds, louvers) are used to block solar radiation, then solar heat gain is reduced, but daylight transmission is also blocked requiring extra interior lighting
Solution Approach 1:
The patent segments the solar spectrum into different wavelength bands (visible, near-infrared, far-infrared) and applies separate optical control mechanisms to each band. The diffractive grating structure spatially separates these spectral components, allowing independent control of daylight (visible) and heat (infrared) transmission through the window system.
Solution Approach 2:
The patent applies local quality by making different parts of the window system have different optical properties for different wavelengths. The diffractive grating directs visible light primarily to the left while directing infrared radiation primarily to the right, creating wavelength-specific transmission paths that allow simultaneous daylight entry and heat rejection.
2Object-affected harmful factors
If spectrally selective coatings are applied to window glass to reject infrared radiation, then solar heat gain is reduced, but the coating property is fixed and cannot adapt to seasonal changes
Solution Approach 1:
The patent implements dynamics by making the window system's optical properties adjustable and controllable. The diffractive grating structure can be configured to direct different wavelengths to different destinations, and the system can dynamically switch between allowing infrared transmission (winter mode) and blocking infrared transmission (summer mode) based on seasonal requirements.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the diffractive grating with specific blaze angles and orientations that are optimized for different seasonal conditions. The window system can be prepared in advance for seasonal changes by adjusting the grating configuration before the heating or cooling season begins.
3Extent of automation
If photochromic windows are used to change optical transparency, then the window responds to light intensity, but it blocks infrared radiation as well as useful visible light in summer months
Solution Approach 1:
The patent segments the optical control function by separating the control of visible light transmission from infrared radiation transmission. The diffractive grating structure spatially divides these spectral components, allowing the window to automatically respond to visible light intensity while maintaining independent control over infrared transmission, thus avoiding the problem of photochromic windows that block both simultaneously.
Solution Approach 2:
The patent uses the diffractive grating as an intermediary element that mediates between incident solar radiation and the interior space. The grating acts as a wavelength-selective mediator that can direct different spectral components to different destinations, enabling selective control of visible and infrared transmission independent of each other.
4Device complexity
If a single diffraction grating is used for both visible and infrared radiation, then the structure is simple, but it cannot efficiently separate different spectral regions
Solution Approach 1:
The patent segments the diffraction grating system into multiple specialized gratings, each optimized for specific wavelength ranges. This segmentation allows each grating to have precisely engineered blaze angles and groove densities tailored to its designated spectral band, achieving high spectral separation efficiency that would be impossible with a single general-purpose grating.
Solution Approach 2:
The patent applies local quality by giving different gratings different optical properties optimized for their specific functions. Each grating in the series has locally optimized characteristics (blaze angle, groove density, material) matched to the spectral region it processes, enabling precise control of different wavelength bands through the window system.
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
This solution enables efficient angular separation of visible and near-infrared radiation, reducing heating and cooling costs while maintaining daylight entry, thereby enhancing energy efficiency and reducing interior lighting needs.
Implementation Method 1
a first blazed diffraction grating for diffracting visible electromagnetic radiation... a second blazed diffraction grating for diffracting near-infrared electromagnetic radiation
Implementation Method 2
Energy-efficient windows incorporating suitably designed diffraction gratings to optimize the efficiency of the utilization of different spectral components of the solar radiation
Data Source
AI summary
Energy-efficient windows incorporating spectrally selective optical elements capable of providing desirable optical characteristics (transmission, reflection, refraction or diffraction) for different wavelengths are disclosed herein. More specifically, energy-efficient windows incorporating suitably designed diffraction gratings to optimize the efficiency of the utilization of different spectral components of the solar radiation are disclosed.