Projector Optical System Diffractive Element Compact Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-performance projector optical systems face challenges in achieving both high image forming performance and small size due to increased lens count for achromatism, leading to larger system size and weight.
Innovation Solution
A projector optical system incorporating a diffractive optical element, specifically a multilayer diffractive optical element with diffraction gratings on two components facing each other, is used in conjunction with a lens group configuration that includes a first lens group, an aperture diaphragm, and a third lens group with positive refractive power, optimizing the air gap and refractive index differences to achieve compactness and effective chromatic aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple lens groups are used to correct chromatic aberration, then image forming performance is improved, but system size increases
Solution Approach 1:
The patent combines refractive optical elements (lens groups) with a diffractive optical element into a single integrated optical system. The diffractive optical element is positioned between the second and third lens groups, merging multiple functions (chromatic aberration correction, light focusing, and beam shaping) into a compact configuration that reduces overall system size while maintaining high image forming performance.
Solution Approach 2:
The patent employs specific parameter relationships to optimize the optical system: G/L ≤ 0.05 where G is the air gap between lens groups and L is the total length, and ΔNd ≤ 0.005 where ΔNd is the refractive index difference between lens materials. These parameter constraints enable compact design while ensuring effective chromatic aberration correction and high-resolution image formation.
2Manufacturing precision
If lens count is increased for achromatism, then chromatic aberration correction is improved, but device complexity increases
Solution Approach 1:
The patent uses composite optical materials by combining refractive index differences between lens groups with diffractive optical elements. This composite approach allows for advanced chromatic aberration correction that cannot be achieved with single-material lens systems, enabling better color accuracy and reduced chromatic aberration while managing system complexity through integrated design.
Solution Approach 2:
The diffractive optical element serves as an intermediary component between the refractive lens groups, mediating the correction of chromatic aberration and other optical imperfections. This intermediary element enables sophisticated optical correction without requiring excessive lens count, as it works in conjunction with the existing lens groups to achieve the desired optical performance.
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 enables good image forming performance while reducing the size and weight of the projector, allowing for efficient chromatic aberration correction and minimizing flare, thus suitable for small projector applications.
Implementation Method 1
a diffractive optical element provided in at least one of the first lens group and the second lens group which are adjacent to the aperture diaphragm
Implementation Method 2
a first lens group having positive refractive power; an aperture diaphragm; a second lens group; a third lens group having positive refractive power
Data Source
AI summary
A projector optical system for forming a real image by projecting an image of a display element has, sequentially from a screen side or an observation side, a first lens group having positive refractive power, an aperture diaphragm, a second lens group, and a third lens group having positive refractive power, with a diffractive optical element being provided on at least one of the first lens group and the second lens group which are adjacent to the aperture diaphragm. The projector optical system satisfies:0.05<G/L<0.9wherein G is an air gap on the optical axis between the second lens group and the third lens group, and L is a length on the optical axis, from the surface that is closest to the screen side to the display element.