Projection Optical System Aberration Control via Dynamic Lens Groups
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Solution Overview
Problem
Existing projection optical systems for projectors face challenges in achieving a wide range of magnification change while maintaining high resolution and brightness, particularly in ultra-wide angle applications, where the system tends to increase in size and complexity, making them unsuitable for portable equipment and bright environments.
Innovation Solution
A projection optical system comprising a first optical group with a fixed positive power and a second optical group with a concave aspheric mirror, where the first optical group is divided into three moving lens groups, including a resin aspheric lens on the outermost enlargement side, to correct aberrations and enhance contrast across a wide range of magnification changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a refraction optical system with multiple lenses is used to achieve wide angle of view, then the angle of view is increased, but the lens size and system complexity are enormously increased
Solution Approach 1:
The optical system is divided into multiple lens groups (first lens group with positive power, second lens group with negative power, and third lens group with positive power) that can move independently. This segmentation allows each group to be optimized for specific functions (wide angle coverage, aberration correction, focusing) rather than requiring a single complex lens to handle all requirements.
Solution Approach 2:
The patent employs dynamic lens groups that can move along the optical axis during focusing operations. The first lens group remains fixed while the second and third lens groups move to adjust focus, enabling the system to maintain wide angle of view across different focus positions without requiring a static, oversized lens configuration.
2Area of moving object
If a refraction/reflection complex optical system with concave mirror is used to achieve ultra-wide angle of view, then the angle of view is increased, but the mirror size and entire length are enormously increased
Solution Approach 1:
The patent extracts the reflective element (concave mirror) from the optical path, using only refractive lens groups to achieve the wide angle of view. This eliminates the need for large mirrors and the associated long optical path lengths, while still achieving the desired wide angle coverage through the multi-group lens configuration.
3Manufacturing precision
If a system with aspheric surfaces is used to correct aberrations, then image quality is improved, but manufacturing accuracy and assembly difficulty are increased
Solution Approach 1:
The patent incorporates aspheric surfaces on specific lens elements (particularly on the second and third lens groups) to correct spherical aberration and other optical imperfections. The aspheric profiles are strategically placed where they provide maximum benefit for image quality while minimizing manufacturing complexity compared to making all surfaces aspheric.
4Illumination intensity
If the F-number is reduced to about 1.7 for high brightness, then brightness is improved, but the range of magnification change is narrowed to about 1.2 times
Solution Approach 1:
The patent employs dynamic lens groups (second and third groups that move during focusing) that enable the system to maintain a low F-number (high brightness) across a wide range of magnification changes. The coordinated movement of these lens groups allows the optical system to preserve both brightness and magnification flexibility, overcoming the trade-off present in fixed-focus systems.
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 allows for a compact, high-resolution image projection system with improved contrast and reduced distortion, suitable for both portable and bright environment applications, by effectively managing aberrations and maintaining brightness across varying magnification ranges.
Implementation Method 1
a second optical group which has one reflective surface having a concave aspheric shape
Implementation Method 2
a resin aspheric lens on the outermost enlargement side
Data Source
AI summary
The 1-2nd lens group is divided into three lens groups which move when focusing is performed during the magnification change. Even in a case in which the second optical group is formed of one mirror, it is possible for a primary image to contain appropriate aberration and to hereby reduce aberration of an image which is finally projected onto a screen through the second optical group.