Projection Optical System Aberration Correction via Intermediate Image
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Solution Overview
Problem
Current projection optical systems fail to achieve a wide angle of view with high projection performance and miniaturization while effectively correcting various aberrations, as they often result in excessive lens size, distortion, and increased total length.
Innovation Solution
A projection optical system comprising a first optical system forming an intermediate image and a second optical system with specific lens groups and optical path bending means, satisfying conditional formulae to optimize focal lengths, refractive powers, and optical axis distances, which includes a first lens group with positive refractive power, a reflective optical path bending means, a second lens group with positive refractive power, and a third lens group with negative refractive power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the focal length is shortened to achieve a wide angle of view, then the angle of view is widened, but the lenses toward the magnification side become excessively large
Solution Approach 1:
The projection optical system is divided into a first optical system and a second optical system that form an intermediate image between them. This segmentation allows the second optical system to have a shorter back focus and smaller lens diameters while achieving a wide angle of view, as the intermediate image formation enables more efficient light path management.
Solution Approach 2:
An intermediate image is formed between the first and second optical systems, serving as an intermediary stage. This intermediate image allows the second optical system to work with reduced requirements for lens size while maintaining wide angle capability, as the intermediate formation point enables optimized light convergence.
2Manufacturing precision
If aberrations are corrected independently by separate optical systems, then each system can be optimized, but the total length of the optical system increases
Solution Approach 1:
The first and second optical systems are combined to form an intermediate image, with the second optical system designed to focus this intermediate image on the magnification side conjugate plane. This merging approach allows for effective aberration correction while maintaining a compact total length, as the systems work cooperatively rather than independently.
Solution Approach 2:
The second optical system is designed with specific local characteristics: a first lens group with positive refractive power, followed by optical path bending means, then a second lens group with positive refractive power, and finally a third lens group with negative refractive power. This localized optimization of refractive powers and optical path management enables effective aberration correction within a compact configuration.
3Adaptability or versatility
If a fish eye lens is used in the second optical system, then the angle of view can be widened, but distortion remains to a great degree in the final image surface
Solution Approach 1:
Instead of using a fish eye lens with extreme parameters, the second optical system employs a third lens group with negative refractive power positioned toward the magnification side. This parameter optimization allows for wide angle of view while controlling distortion to acceptable levels, achieving a balance between angular coverage and image quality.
Solution Approach 2:
The second optical system uses a distributed arrangement of lens groups with different refractive powers (positive, positive, negative) rather than a single fish eye element. This localized distribution of optical functions corrects distortion while maintaining wide angle capability, as each lens group contributes to specific aspects of image quality.
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 a projection optical system with high performance, wide angle of view, and miniaturization, effectively correcting aberrations such as field curvature and distortion, while maintaining a compact design.
Implementation Method 1
a first optical system constituted by a plurality of lenses that forms the image displayed by the image display elements as an intermediate image
Implementation Method 2
a first optical path bending means for bending an optical path with a reflective surface
Implementation Method 3
a second optical system constituted by a plurality of lenses that focuses the intermediate image on the magnification side conjugate plane
Data Source
AI summary
A projection optical system is constituted by, in order from the reduction side, a first optical system for forming an image displayed by image display elements as an intermediate image, and a second optical system for forming the intermediate image on a magnification side conjugate plane. The second optical system is constituted by, in order from the reduction side, a first lens group having a positive refractive power, a first optical path bending means that bends an optical path with a reflective surface, a second lens group having a positive refractive power, a second optical path bending means that bends an optical path with a reflective surface, and a third lens group having a negative refractive power. Conditional Formulae (1) and (2) below are satisfied.0.05<|f23|/D223<0.50 (1)5.0<D212/|f|<20.0 (2).