Prism Projection Optics for Short Throw and Distortion Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical systems face challenges in achieving a shorter focal length and larger-sized screen while maintaining optical performance and reducing the size of the prism.
Innovation Solution
An optical system with a reduction conjugate point and a magnification conjugate point, incorporating a prism with specific optical surfaces and a first sub-optical system, which includes an aperture stop positioned between these points, and a second sub-optical system with a prism having transmission and reflection surfaces, allowing for a compact design and excellent optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If a smaller prism is used, then the overall size and weight of the optical system are reduced, but achieving shorter focal length and larger screen becomes more difficult
Solution Approach 1:
The optical system is divided into multiple sub-optical systems: a first sub-optical system containing rotationally symmetric lens elements for initial light path control, and a second sub-optical system containing the prism with asymmetric surfaces for final light path adjustment. This segmentation allows each component to be optimized independently, enabling the prism to be smaller while still achieving the required focal length and screen size.
Solution Approach 2:
The prism employs asymmetric surface geometry with different curvatures in different directions (first direction and second direction perpendicular to the optical axis). This multi-dimensional surface design enables compact light path folding while maintaining the required optical path length for short focal length projection onto a large screen.
2Length of stationary object
If a smaller prism is used, then the overall length of the optical system is reduced, but maintaining optical performance becomes more difficult
Solution Approach 1:
Different surfaces of the prism are designed with different local properties: the first transmission surface has a first curvature in the first direction and a second curvature in the second direction, while the second transmission surface has different curvatures. This local quality differentiation enables precise control of light path and aberration correction within a compact structure, maintaining excellent optical performance.
Solution Approach 2:
The optical system combines multiple types of optical elements with different properties: rotationally symmetric lens elements in the first sub-optical system and an asymmetric prism in the second sub-optical system. This composite approach leverages the advantages of each element type to achieve both compact size and high optical performance.
3Device complexity
If the prism size is reduced, then the device complexity is lowered, but distortion correction becomes more challenging
Solution Approach 1:
The prism employs asymmetric surface geometry where the first transmission surface and second transmission surface have different curvature characteristics in perpendicular directions. This asymmetric design provides enhanced degrees of freedom for distortion correction while maintaining a compact overall size, effectively addressing the contradiction between device complexity and manufacturing precision.
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 system achieves a shorter focal length and larger-sized screen while maintaining excellent optical performance and reducing the overall length and weight of the optical system, with improved distortion correction and balanced center of gravity.
Implementation Method 1
a prism PM having a first transmission surface T1 located on a reduction side, a second transmission surface T2 located on a magnification side, and a first reflection surface R1 and a second reflection surface R2 located on an optical path between the first transmission surface T1 and the second transmission surface T2
Implementation Method 2
a first reflection surface R1 and a second reflection surface R2 located on an optical path between the first transmission surface T1 and the second transmission surface T2
Implementation Method 3
The first reflection surface R1 has a shape in which a concave surface is oriented in a direction in which light rays made incident on the first reflection surface R1 are reflected
Implementation Method 4
The first sub-optical system includes a plurality of rotationally symmetric lens elements
Data Source
AI summary
The optical system includes a first sub-optical system including an aperture stop and a second sub-optical system including a prism. The prism has a first transmission surface located on a reduction side, a second transmission surface located on a magnification side, and at least one reflection surface between the first transmission surface and the second transmission surface. The first sub-optical system includes a plurality of rotationally symmetric lens elements. When the axis passing through at least two centers of the rotationally symmetric lens element is defined as a reference optical axis, at least one optical surface of the prism is formed such that in a plane perpendicular to the reference optical axis, a maximum angle θmax and a minimum angle θmin in terms of an angle at which a principal ray of light rays having an image-forming relationship on a concentric circle centered on an intersection of the reference optical axis and a reduction conjugate point of the rectangular region intersects a normal line of the plane at a position where the principal ray is made incident on the optical surface satisfy the following Expression (1): 45°>|θmax|−|θmin|>0.014°.