Projection Optical System with Intermediate Image for Compact High Resolution
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Solution Overview
Problem
Existing laser scanning projectors face challenges in achieving high resolution while maintaining a small size and long projection distance, as increasing resolution leads to upsizing of the apparatus and deterioration of response characteristics, and existing methods to increase resolution are incompatible with maintaining focus-free characteristics.
Innovation Solution
A projection optical system is designed with a first lens group that condenses light from a light source to a primary image-forming point between the first and second lens groups, allowing for a small-sized, lightweight projector with high resolution, by optimizing the numerical aperture and beam diameter, and using a scanning mirror positioned in proximity to the primary image-forming point to increase the numerical aperture at the secondary image-forming point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution of the projector is increased, then the image quality is improved, but the apparatus size increases
Solution Approach 1:
The optical system is divided into two separate lens groups (first lens group and second lens group) with an intermediate image-forming point positioned between them. This segmentation allows the system to achieve high resolution through optimized numerical aperture while maintaining a compact overall structure, resolving the contradiction between resolution and apparatus size.
Solution Approach 2:
The patent introduces an intermediate image-forming point in the optical path between the two lens groups, adding a dimensional element to the optical configuration. This intermediate imaging stage enables the system to achieve high resolution without proportionally increasing the apparatus size, as the intermediate point allows for optimized beam diameter and numerical aperture at different stages.
2Measurement precision
If the numerical aperture is increased to improve resolution, then the image quality is improved, but the apparatus size increases
Solution Approach 1:
The optical system is divided into two separate lens groups (first lens group and second lens group) with an intermediate image-forming point positioned between them. This segmentation allows the system to achieve high resolution through optimized numerical aperture while maintaining a compact overall structure, resolving the contradiction between resolution and apparatus size.
Solution Approach 2:
The patent optimizes the numerical aperture locally at the intermediate image-forming point and at the final image plane, rather than requiring uniformly high numerical aperture throughout the entire optical path. This local optimization allows high resolution to be achieved without proportionally increasing the apparatus size, as the numerical aperture can be tailored to specific critical regions of the optical system.
3Length of stationary object
If the projection distance is increased, then the projection capability is improved, but the focus-free characteristics deteriorate
Solution Approach 1:
The optical system is divided into two separate lens groups (first lens group and second lens group) with an intermediate image-forming point positioned between them. This segmentation allows the system to achieve high resolution through optimized numerical aperture while maintaining a compact overall structure, resolving the contradiction between resolution and apparatus size.
Solution Approach 2:
The patent employs an optical configuration that dynamically adapts to different projection distances through the intermediate image-forming point. The two-lens-group design with intermediate imaging enables the system to maintain stable focus-free characteristics across varying projection distances, as the intermediate point serves as a reference that stabilizes the optical path regardless of the final projection distance.
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 projector with high resolution and a long projection distance, while maintaining a compact size and preventing deterioration in mirror characteristics, thus achieving a balance between resolution and apparatus size.
Implementation Method 1
a first lens group that includes one or more lenses, has a positive focal length, and condenses light from the light source on a primary image-forming point that is an image of the light source
Implementation Method 2
a deflector that scans light from the first lens group
Implementation Method 3
a second lens group that includes one or more lenses, has a positive focal length, and forms an image of light from the deflector at a position of a secondary image-forming point that is an image of the primary image-forming point
Data Source
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AI summary
A projection optical system according to the present disclosure includes, in order from a side on which a light source is located to a projection side along an optical axis: a first lens group that includes one or more lenses, has a positive focal length, and condenses light from the light source on a primary image-forming point that is an image of the light source; a deflector that scans light from the first lens group; and a second lens group that includes one or more lenses, has a positive focal length, and forms an image of light from the deflector at a position of a secondary image-forming point that is an image of the primary image-forming point, and the first lens group forms the primary image-forming point between the first lens group and the second lens group along the optical axis.