Ultrawide Projection System with Folded Optical Path
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Solution Overview
Problem
Existing projection systems face challenges in achieving a wide field angle while maintaining a compact configuration and avoiding performance deterioration, particularly in achieving an ultrawide half angle of view greater than or equal to 50° without increasing the size of the projection system.
Innovation Solution
A projection system comprising a first optical group formed of a plurality of lenses and a second optical group with a concave mirror, along with an optical path deflection system using two optical path deflectors, is designed to achieve an ultrawide field angle. The optical path deflectors are strategically placed between the first and second optical groups to fold the optical path, allowing for a compact configuration while maintaining performance by satisfying specific conditional expressions for the distances and focal lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a refractive optical system is used to achieve a wide field angle, then the field angle can be increased, but a very large lens is required on the enlargement side which increases the size of the projection system
Solution Approach 1:
The optical system is divided into multiple lens groups (first through fourth lens groups) with specific positive and negative powers arranged in sequence. This segmentation allows each group to contribute differently to the overall optical function, enabling wide field angle achievement without requiring a single large lens, thus reducing the overall system size.
Solution Approach 2:
Different lens groups are assigned specific optical powers and positions to optimize local optical characteristics. The first lens group has positive power and is positioned closest to the object, while the fourth lens group has positive power and is positioned closest to the image plane. This local optimization of optical properties enables wide field angle without proportionally increasing system size.
2Difficulty of detecting and measuring
If a concave mirror is used to achieve an ultrawide half angle of view greater than or equal to 70°, then the field angle is improved, but an intermediate image is generated which increases the length of the overall projection system
Solution Approach 1:
The concave mirror that would generate an intermediate image is replaced by a refractive optical system comprising four lens groups. This extraction of the mirror-based intermediate image formation eliminates the need for the additional optical path length required by mirror systems, achieving wide field angle without the penalty of increased system length.
Solution Approach 2:
The mechanical mirror-based optical system is replaced by a refractive lens-based system. The four lens groups work together to achieve the wide field angle function previously accomplished by a concave mirror, but without generating an intermediate image that would increase system length.
3Volume of stationary object
If reflection surfaces are provided in a relay lens system to reduce size, then the projection system size is reduced, but performance deteriorates due to shift and inclination of the optical axis between lens groups
Solution Approach 1:
The first and second lens groups are positioned adjacent to each other with minimal spacing, and the third and fourth lens groups are positioned adjacent to each other. This merging of lens groups reduces the need for intermediate reflection surfaces that would cause optical axis shifts, thereby maintaining performance while reducing system size.
Solution Approach 2:
The optical design achieves compactness through careful arrangement of lens groups in the optical path dimension rather than using reflection surfaces that would introduce misalignment issues. The four lens groups are positioned along the optical axis in a compact configuration that avoids the need for folding the optical path via mirrors.
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 the projection system to achieve an ultrawide field angle of 50° or greater, maintaining a compact size and suppressing performance deterioration, thus enhancing the projection system's efficiency and installability.
Implementation Method 1
a first optical group formed of a plurality of lenses and a second optical group formed of at least a single optical element with the first optical group and the second optical group sequentially arranged from a reduction side
Implementation Method 2
The second optical group enlarges the intermediate image formed by the first optical group and projects the enlarged intermediate image with a half angle of view being greater than or equal to 50°
Data Source
AI summary
A first optical group that forms an intermediate image and a second optical group that enlarges and projects the intermediate image formed by the first optical group satisfy a variety of conditions. Therefore, first of all, in a case where a projection system is incorporated in a projector, an ultrawide field angle that allows enlargement and projection of an image at a half angle of view of 50° or greater is achieved. Further, an optical path deflection system including two optical path deflectors is disposed between the first optical group and the second optical group to allow the optical path to be folded with deterioration in performance of the projection system suppressed.