Compact Projection Optical System with Free-Form Surface
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Solution Overview
Problem
Conventional projection optical systems and image projecting apparatuses face challenges in achieving a compact design capable of projecting high-quality images at shorter distances without compromising image quality or increasing the system's size.
Innovation Solution
A projection optical system comprising a first refractive optical system with a positive power and a second reflection optical system, including a free-form surface, which projects an image onto a surface while maintaining a throw ratio of Tr ≤ 0.7, allowing for a more compact design and improved image quality by optimizing the length of the intermediate image and the optical path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional projection optical system is used, then the system can project images, but the system size is large and the projection distance is long
Solution Approach 1:
The projection optical system is divided into two distinct optical systems: a first optical system for forming an intermediate image and a second optical system for projecting the final image. This segmentation allows each system to be optimized independently, enabling compact design while maintaining short projection distance.
Solution Approach 2:
The system introduces an intermediate image plane that adds a spatial dimension to the projection path. By forming an intermediate image first and then projecting it to the final image plane, the system achieves compact configuration in the optical path dimension while maintaining short projection distance.
2Volume of moving object
If the projection distance is shortened, then the system becomes more compact, but image quality deteriorates due to increased aberration
Solution Approach 1:
Dividing the projection into two stages with intermediate imaging allows each optical system to be designed with specific aberration correction capabilities. The first system handles initial image formation while the second system optimizes for final image quality, enabling short projection distance without sacrificing image quality.
Solution Approach 2:
Each optical system is designed with specific local characteristics: the first optical system optimizes for intermediate image formation while the second optical system optimizes for final image quality and aberration correction. This local optimization enables compact design while maintaining high image quality.
3Manufacturing precision
If the intermediate image length is increased, then aberration correction improves, but the system size increases
Solution Approach 1:
The two-stage projection system allows the intermediate image to be formed at an optimized position and size. By segmenting the projection path, the system can achieve effective aberration correction through the intermediate image without requiring excessive system size, as each stage can be compactly designed.
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 solution enables a more compact projection optical system that can project high-quality images at shorter distances, reducing the risk of image obstruction and improving aberration correction, thus providing a better image projection with reduced system size and distortion.
Implementation Method 1
a first optical system which forms an intermediate image conjugate to an object and has an optical axis
Implementation Method 2
a second optical system which forms an image conjugate to the intermediate image on a surface to be projected on
Data Source
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AI summary
Disclosed is a projection optical system including a first optical system configured to form a first image conjugate to an object and have an optical axis and a second optical system configured to project a second image conjugate to the first image onto a surface to be projected on, wherein the first image satisfies a condition of: wherein Im denotes a length of the first image in a direction of an optical axis of the first optical system, normalized by a focal length of the first optical system, and Tr denotes a throw ratio for the projection optical system.