Projection Optical System Aberration Correction via Movable Lens Group
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Solution Overview
Problem
Existing projection optical systems face challenges in projecting sharp, wide-angle images with minimal aberrations and fluctuations in image formation performance due to changes in projection distance and temperature, particularly in maintaining a deep depth of field and focus while correcting for chromatic aberrations and curvature of field.
Innovation Solution
A projection optical system comprising a first refractive optical system, a second refractive optical system with a moving focus lens group, and a reflective optical system with a stationary reflective surface, where the second refractive optical system has a larger correction effect for curvature of field and distortion, and the first refractive optical system corrects coma aberration, allowing for fine adjustment of focus and suppression of aberration fluctuations through strategically positioned and moving lens groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a wide-angle projection optical system with short focal length is used, then the projection angle is increased, but fluctuations in curvature of field increase in the periphery of projected images when projection distance changes
Solution Approach 1:
The patent applies dynamics by making the focus lens group movable along the optical axis. This allows the system to dynamically adjust focus and correct curvature of field fluctuations in real-time based on projection distance changes, thereby maintaining image quality across the wide projection angle without sacrificing precision
Solution Approach 2:
The patent changes the position parameter of the focus lens group to correct aberrations. By adjusting the lens group's position along the optical axis, the system modifies optical parameters to compensate for curvature of field fluctuations, enabling wide-angle projection while maintaining manufacturing precision
2Length of moving object
If the projection distance between the reflective surface and screen is reduced, then the projection space is minimized, but focus fluctuations increase in the periphery of projected images
Solution Approach 1:
The movable focus lens group enables dynamic compensation for focus fluctuations that occur when projection distance is reduced. This allows the system to achieve compact projection space while maintaining focus precision through real-time optical adjustment
Solution Approach 2:
The patent replaces mechanical adjustment of the entire optical system with a more efficient mechanism: moving only the focus lens group. This substitution achieves the same focus correction effect with minimal mechanical movement, enabling compact projection space without sacrificing image quality
3Manufacturing precision
If multiple lens groups are added to correct aberrations, then image sharpness is improved, but the device complexity increases
Solution Approach 1:
The patent segments the optical system into distinct functional groups: a stationary reflective surface, a first refractive optical system, and a movable second refractive optical system containing the focus lens group. This segmentation allows each component to be optimized for its specific function while maintaining overall system simplicity
Solution Approach 2:
By making only the focus lens group movable rather than adjusting multiple lens groups, the patent reduces mechanical complexity while maintaining image sharpness. The dynamic adjustment of a single lens group is sufficient to correct the primary aberrations in the wide-angle projection system
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 sharp, enlarged images with reduced aberrations and improved image formation performance across varying projection distances and temperatures, maintaining a deep depth of field and focus while simplifying the configuration of the second refractive optical system and minimizing the influence of mounting tolerance.
Implementation Method 1
a first refractive optical system that forms a first intermediate image on an enlargement side using light incident from a reducing side
Implementation Method 2
a second refractive optical system that forms the first intermediate image into a second intermediate image on the enlargement side
Implementation Method 3
a first reflective optical system including a first reflective surface with positive refractive power that is positioned on the enlargement side of the second intermediate image
Data Source
AI summary
A projection optical system (2) projects from a DMD (7) on a reducing side onto a screen (9) on an enlargement side, and includes: a first refractive optical system (10) that forms a first intermediate image (51) on the enlargement side using light incident from the reducing side; a second refractive optical system (20) that forms the first intermediate image (51) on the reducing side into a second intermediate image (52) on the enlargement side; and a first reflective optical system (30) including a first reflective surface (31a) with positive refractive power that is positioned on the enlargement side of the second intermediate image (52), wherein the second refractive optical system (20) includes a first focus lens group (61) that moves when focusing is carried out, and the first focus lens group (61) includes at least one lens (L13) included in the second refractive optical system (20).