Liquid Crystal Beam Shaper for Constant Color Temperature
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Solution Overview
Problem
Dynamic liquid crystal beam shapers cause a drop in correlated color temperature (CCT) at the center of the beam due to chromatic aberrations, leading to unacceptable changes in 'color over angle' distribution, particularly in applications like museums where CCT stability is crucial.
Innovation Solution
A beam shaping lens with a variable refractive index, combined with a CCT correction unit and an electrically tunable spectral filter, maintains a constant CCT across different angles by adjusting the color temperature and spectral content of the light beam, using a liquid crystal-based device to control the beam's shape and an angle adjuster interface to receive beam angle signals for precise CCT adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a dynamic liquid crystal beam shaper is used to control beam shape and broaden illumination area, then the beam angle and illumination area can be dynamically adjusted, but the correlated color temperature (CCT) drops at the center of the beam due to chromatic aberrations
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the refractive index of the liquid crystal material through voltage control. By changing the refractive index parameter, the beam shaping lens can control the beam angle and illumination area while compensating for chromatic aberrations to maintain constant CCT. The system modifies optical parameters (refractive index) to achieve both beam control and color temperature stability.
Solution Approach 2:
The patent implements feedback control by using a control unit that receives signals about the desired beam angle and illumination area, then adjusts the liquid crystal lens parameters accordingly. The system monitors the beam characteristics and makes real-time adjustments to maintain constant CCT while achieving the desired beam shaping, creating a closed-loop control system that compensates for chromatic aberrations.
2Ease of manufacture
If standard optical materials are used to create lenses for beam broadening, then the lens structure is simple and cost-effective, but chromatic aberrations cause different wavelengths to focus at different positions, changing the color over angle (COA) distribution
Solution Approach 1:
The patent uses liquid crystal material as a composite optical medium that combines the benefits of standard optical materials (ease of manufacture) with the ability to dynamically control refractive index. The liquid crystal layer works in conjunction with standard lens structures to achieve beam shaping while compensating for chromatic aberrations, maintaining stable COA distribution through material properties that can be electrically tuned.
Solution Approach 2:
The patent introduces dynamics by using a liquid crystal beam shaping lens where the refractive index can be dynamically adjusted through applied voltage. This dynamic property allows the lens to adapt its optical characteristics in real-time, compensating for chromatic aberrations and maintaining stable COA distribution across different beam angles, unlike static standard optical materials.
3Use of energy by moving object
If blue LED-pumped phosphor light sources are used to achieve white light, then the light source is efficient and compact, but the broadened light beam loses its CCT in the center compared to the periphery due to wavelength-dependent broadening
Solution Approach 1:
The patent introduces the liquid crystal beam shaping lens as an intermediary element between the blue LED-pumped phosphor light source and the final beam output. This intermediary device compensates for the wavelength-dependent broadening effect by dynamically adjusting the refractive index to counteract chromatic aberrations, ensuring that the CCT remains uniform across the beam center while preserving the efficiency of the LED light source.
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 ensures a consistent CCT variation of less than 200K across the beam, maintaining color stability even as the beam is broadened, effectively addressing the CCT drop issue in dynamic lighting systems.
Implementation Method 1
The operation of this device is based on the dynamic generation of micro lens arrays that can focus light very tightly at different positions over the transversal plane of the clear aperture of the light source and result into the broadening of the illumination area in a controllable way.
Implementation Method 2
The PCT application with international publication number WO2017041167A1 discloses liquid crystal (LC) based device that enables the dynamic control of the light beam's shape (LC beam shaper)
Implementation Method 3
The above-mentioned LC micro lenses have chromatic aberrations as almost all other lenses made of standard optical materials. These aberrations may be conditioned by the profile of the refractive index as well as by material's dispersion (the dependence of the material's refractive index upon the light wavelength).
Data Source
AI summary
A variable angle beam control device is capable of maintaining the same color temperature of the light source regardless of the changes in the angle of the beam. The controllable light beam device has a light source with primary optics producing a low divergence light beam having an inverted angular distribution of the correlated color temperature (CCT), and a liquid crystal device with an electrically variable refractive index distribution arranged to receive said light beam and to provide a variable angle beam.