Projection Optics Chromatic Aberration Correction
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Solution Overview
Problem
Entertainment lighting systems using LED sources often suffer from residual chromatic aberration, particularly when projecting images out of focus, leading to uneven color mixing and the presence of unwanted halos around image boundaries, which are not adequately corrected by existing solutions.
Innovation Solution
Incorporating a diffuser with adjustable position or varying diffusive properties at the gobo plane, coupled with an achromatic doublet and singlet lens system in the projection optics, to minimize axial and lateral chromatic aberrations and achieve smoother image projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single lens is used to project light onto the projection plane, then the device complexity is reduced, but chromatic aberration increases causing colored fringes and uneven color mixing
Solution Approach 1:
The single projection lens is segmented into multiple lenses with different refractive indices (first lens with lower refractive index, second lens with higher refractive index). This segmentation allows each lens to contribute differently to chromatic aberration correction, with the first lens providing base focusing and the second lens compensating for chromatic errors, thereby reducing overall chromatic aberration while maintaining reasonable device complexity
Solution Approach 2:
The optical system uses composite lens structures combining materials with different refractive indices. The first lens is made of material with lower refractive index while the second lens uses material with higher refractive index, creating a composite optical system that leverages the complementary properties of different materials to correct chromatic aberration that cannot be achieved with a single material
2Object-affected harmful factors
If the projection optics are adjusted to correct chromatic aberration, then color mixing improves, but the image sharpness and contour definition deteriorate
Solution Approach 1:
The system changes optical parameters by using lenses with specific refractive index values (first lens: lower refractive index, second lens: higher refractive index) and controlling their relative positions and focal lengths. This parameter optimization allows the system to achieve both good color mixing (reducing chromatic aberration) and sharp image contours simultaneously, rather than sacrificing one for the other
3Object-affected harmful factors
If a diffuser is added to reduce chromatic aberration, then halo effects decrease, but light efficiency and image brightness are reduced
Solution Approach 1:
The patent replaces the mechanical/diffusive approach (using physical diffusers to scatter light and reduce halos) with an optical design approach (using multi-lens systems with specific refractive indices to correct chromatic aberration optically). This substitution eliminates the need for diffusers that would attenuate light, thereby maintaining high light efficiency while still reducing halo effects through proper optical design
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 configuration significantly reduces chromatic aberrations and halo effects, allowing for more accurate and controlled image projection with sharper contours and maintained detail, even in out-of-focus scenarios, while maintaining acceptable efficiency.
Implementation Method 1
coupling to the gobo a light diffuser (22) to provide diffusion of light radiation at the gobo (16)
Implementation Method 2
achromatic doublet and singlet lens system in the projection optics, to minimize axial and lateral chromatic aberrations
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
A lighting device (10) such as a projector employed in the field of show and entertainment, comprises: - a light radiation source (12), - a first optical system (14) configured to project light radiation from the light radiation source (12) onto a gobo plane (GP), - a holder (18) of gobo (16), configured to hold a gobo (16) at the gobo plane (GP), - a second optical system (20) configured to project towards a projection surface (PP) light radiation projected onto the gobo plane (GP), and - a light diffuser (22) configured to be coupled to a gobo (16) held at the gobo plane (GP) by gobo holder (18).