Projection Lens System Optical Path Folding
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Solution Overview
Problem
Existing projection optical apparatuses face challenges in reducing size while maintaining image quality, as folding the optical path leads to increased size and cost of components, particularly the concave mirror, and results in image degradation due to errors from folding mirror shape.
Innovation Solution
Folding the light beam closer to the spatial light modulator within the projection lens system, using lenses with positive power to prevent beam spreading, and balancing aberrations to control image quality and reduce apparatus size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the optical path is folded using a concave mirror and folding mirrors to reduce projection distance, then the projection distance is reduced, but the apparatus height and depth increase due to the size of the concave mirror and optical path deflection requirements
Solution Approach 1:
The patent folds the optical path within the projection lens system by deflecting the optical axis at multiple stages using folding mirrors, transforming the linear optical path into a multi-dimensional folded configuration. This allows the light beam to traverse a longer effective path within a compact apparatus footprint, reducing projection distance without proportionally increasing apparatus external dimensions.
Solution Approach 2:
The optical path folding is nested within the projection lens system itself, with folding mirrors positioned at strategic locations inside the lens assembly. This nested configuration allows the optical path to be folded without requiring additional external space, as the folding mechanism is integrated within the existing lens system boundaries.
2Volume of stationary object
If folding mirrors are used to deflect the optical path, then the apparatus size is reduced, but image quality degrades due to errors from folding mirror shape
Solution Approach 1:
The patent introduces intermediate imaging lenses between the folding mirrors and the spatial light modulator. These intermediary lenses serve to correct and balance aberrations introduced by the folding mirrors, acting as mediators that compensate for the negative effects of optical path folding while maintaining the compact apparatus configuration.
Solution Approach 2:
The patent carefully controls the optical parameters of the folding mirrors and imaging lenses, including their positions, curvatures, and focal lengths. By optimizing these parameters, the system minimizes aberration effects from the folding mirrors while maintaining the desired compact form factor, thus balancing apparatus size reduction with image quality preservation.
3Volume of stationary object
If the optical path is folded to reduce apparatus depth, then dead space is utilized more effectively, but the light beam spreads which degrades image quality
Solution Approach 1:
The patent employs positive power imaging lenses positioned to prevent beam spreading before the light reaches critical optical elements. These lenses perform preliminary correction of the light beam configuration, ensuring that the beam maintains its convergence properties throughout the folded optical path, thereby preventing image quality degradation that would result from beam spreading.
4Volume of stationary object
If components are minimized in size to reduce apparatus volume, then the apparatus becomes more compact, but aberration control becomes more difficult affecting image quality
Solution Approach 1:
The patent optimizes the optical parameters of all components including the folding mirrors and imaging lenses, carefully selecting their positions, curvatures, and focal lengths to balance aberration control with compact size. By precisely controlling these parameters, the system achieves effective aberration management within a minimized apparatus volume.
Solution Approach 2:
Intermediate imaging lenses are strategically positioned within the compact apparatus to serve as aberration correction elements. These intermediary components compensate for the increased aberration effects that result from miniaturization, allowing the system to maintain image quality despite the reduced component sizes and compact overall configuration.
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 approach reduces the depth and height of the apparatus, effectively utilizing dead space, minimizing the size of components, and maintaining image quality by controlling light beam spread and aberrations, thus achieving a more compact and cost-effective projection optical apparatus.
Implementation Method 1
a projection lens system, comprising: a first optical system, disposed closer to the spatial light modulator with reference to a folded space, for transmitting light
Implementation Method 2
an optical path deflecting unit, disposed in the optical path space in the first optical system, for deflecting the optical axis
Implementation Method 3
using lenses with positive power to prevent beam spreading, and balancing aberrations to control image quality
Data Source
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AI summary
A projection optical apparatus capable of providing high image quality and having a reduced size. The projection optical apparatus comprises a light valve and a projection optical system including a first optical system(5) having a transmissive-ref ractive element and a second optical system (3') having a reflective-refractive element. An image formed on the light valve is projected by the projection optical system on a projection surface (4). The optical axis in the first optical system(5) is folded both vertically and horizontally. The first group (5A) of the first optical system is contained in a space (dead space) whose lower limit is defined by a lower edge of the second optical system(3') / thereby reducing the depth of the apparatus.