Convex Transmissive Surface Reduces Reflective Size in Projection Systems
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Solution Overview
Problem
In projection systems with a reflective surface on the magnifying side of an intermediate image, shortening the projection distance leads to an increase in the size of the reflective surface, making it challenging to maintain a compact system while preventing distortion and aberrations.
Innovation Solution
Incorporating a second transmissive surface with a convexly curved shape in the second optical system, which refracts light and reduces the size of the reflective surface, allowing for a shorter focal length and minimizing the increase in reflective surface size, even at shorter projection distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the projection distance is shortened in a projection system with a reflective surface on the magnifying side of an intermediate image, then the projection system becomes more compact, but the size of the reflective surface increases
Solution Approach 1:
The second optical system is divided into multiple functional surfaces: a reflective surface for folding the optical path and convex transmissive surfaces for aberration correction. This segmentation allows each surface to have a specialized function, enabling the reflective surface to remain compact while the convex surfaces correct the field curvature and aberrations that would otherwise require a larger reflective surface.
Solution Approach 2:
The patent employs convexly curved transmissive surfaces in the second optical system to counterbalance the field curvature introduced by the concave reflective surface. The specific curvature of these convex surfaces is designed to correct spherical aberration and other optical imperfections, allowing the system to maintain image quality with a compact reflective surface size.
2Length of moving object
If the projection distance is shortened, then the system becomes more compact, but field curvature and aberrations increase
Solution Approach 1:
The patent uses convexly curved transmissive surfaces strategically positioned in the second optical system to counterbalance the field curvature generated by the concave reflective surface. The curvature of these convex surfaces is specifically designed to correct spherical aberration and other optical imperfections, maintaining image quality even at shortened projection distances.
Solution Approach 2:
The patent optimizes various parameters including the refractive indices of the convex transmissive surfaces, their curvature radii, and their positions relative to the reflective surface. By carefully adjusting these parameters, the system achieves aberration correction and maintains image quality while keeping the projection distance short.
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 more compact projection system with reduced field curvature and aberrations, maintaining image quality and preventing the need for larger reflective surfaces, while allowing for efficient light distribution across the screen.
Implementation Method 1
the second transmissive surface has a convexly curved shape protruding toward the magnifying side... which refracts light and reduces the size of the reflective surface
Implementation Method 2
The reflective surface has a concavely curved shape... forms an intermediate image in a position between the first optical system and the reflection surface
Data Source
AI summary
A projection system has a first optical system and a second optical system arranged on a magnifying side of the first optical system. The projection system forms an intermediate image in a position between a demagnifying-side image formation plane and a magnifying-side image formation plane of the projection system. The second optical system is an optical element having a first transmissive surface, a reflective surface, and a second transmissive surface arranged from a demagnifying side toward the magnifying side. The first transmissive surface and the reflective surface are located at one side with respect to an optical axis. The second transmissive surface is located at another side with respect to the optical axis. The reflective surface has a concavely curved shape. The second transmissive surface has a convexly curved shape protruding toward the magnifying side.