Projection System Lens Group Power Distribution for Aberration Control
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Solution Overview
Problem
The existing projection systems, such as described in JP-A-2018-97046, face a decrease in resolution performance due to the lens group on the reduction side affecting the optical performance, particularly with larger positive power lenses leading to increased aberrations from manufacturing errors.
Innovation Solution
A projection system with a first optical system of positive power and a second optical system of negative power, where the second optical system includes a first lens group on the enlargement side of the intersection position, a second lens group with negative power on the reduction side, and a third lens group with positive power, distributing power among multiple lenses to minimize aberrations and improve resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single lens with large positive power is used in the second optical system, then the back focal length can be sufficient, but manufacturing errors cause large aberrations and resolution performance decreases
Solution Approach 1:
The patent divides the second optical system into multiple lens groups (first, second, and third lens groups) instead of using a single lens. The second lens group is further divided into multiple lenses with different powers. This segmentation distributes the optical power across multiple elements, reducing the impact of manufacturing errors on overall aberration and improving resolution performance.
Solution Approach 2:
The patent assigns different power characteristics to different lens groups: the first lens group has positive power, the second lens group has negative power, and the third lens group has positive power. This local differentiation of optical properties allows each lens group to contribute differently to aberration correction, with the negative power second lens group specifically addressing aberrations caused by the positive power lenses.
2Manufacturing precision
If the power is concentrated in fewer lenses, then the system structure is simpler, but aberrations increase and resolution performance decreases
Solution Approach 1:
The optical system is segmented into three main lens groups within the second optical system, with the second lens group containing multiple individual lenses. This segmentation improves resolution by distributing power and reducing aberrations, while the modular lens group structure maintains manageable system complexity through organized functional divisions.
3Length of stationary object
If lenses with larger power are used, then the back focal length can be maintained, but aberrations from manufacturing errors increase
Solution Approach 1:
Instead of relying on a single high-power lens to achieve the required back focal length, the patent segments the optical power across multiple lens groups. The positive power first and third lens groups contribute to back focal length, while the negative power second lens group corrects aberrations, achieving both goals simultaneously through distributed power design.
Solution Approach 2:
Different lens groups are assigned different power signs (positive and negative) to perform different functions: the positive power lenses help establish the back focal length, while the negative power second lens group specifically addresses aberration correction, allowing the system to maintain back focal length without sacrificing resolution 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
The configuration enhances resolution performance by distributing power among lenses, reducing aberrations and maintaining a balanced correction of spherical aberrations, field curvature, and distortion, while ensuring a sufficient back focal length without increasing the overall system size.
Implementation Method 1
a first optical system having positive power and a second optical system disposed on a reduction side of the first optical system and having negative power. An intermediate image conjugate with an enlargement-side conjugate plane and a reduction-side conjugate plane of the projection system is formed between the first optical system and the second optical system.
Data Source
AI summary
A projection system includes a first optical system and a second optical system. The second optical system includes a first lens group disposed on an enlargement side of an intersection position where a chief ray of an off-axis beam having a maximum angle of view intersects with an optical axis of the projection system in the second optical system, a second lens group disposed on the reduction side of the intersection position and having negative power, and a third lens group disposed on the reduction side of the second lens group and having positive power. The second lens group includes a first lens having positive power, a second lens disposed on the reduction side of the first lens and having positive power, and a third lens disposed on the reduction side of the second lens and having negative power. The third lens group includes two lenses each having positive power.