Projection Optical System Aspherical Lens Zoom Mechanism
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Solution Overview
Problem
Existing projection optical systems with high zoom ratios face challenges in maintaining sufficient resolution performance across the entire zoom range while minimizing total lens length.
Innovation Solution
A projection optical system comprising multiple lens groups, including a first lens group with negative power and at least one aspherical lens, with specific lens configurations and movements during zooming to maintain resolution and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of aspherical lenses is reduced from two to one in the first lens group, then the manufacturing complexity and cost are reduced, but the ability to correct aberrations may deteriorate
Solution Approach 1:
The patent applies local quality by introducing an aspherical surface specifically in the first lens group to correct aberrations at critical locations in the optical path. Instead of making all lenses aspherical, only the first lens group contains an aspherical lens, concentrating the aberration correction function where it is most needed while keeping other lenses simple spherical shapes for easier manufacturing.
Solution Approach 2:
The patent employs asymmetry by using an aspherical lens design in the first lens group rather than symmetric spherical lenses. The aspherical surface has different curvatures at different radial positions, allowing it to correct various aberrations (spherical aberration, coma, astigmatism) that cannot be corrected by symmetric spherical lenses, thereby improving optical performance while limiting aspherical surfaces to only where necessary.
2Adaptability or versatility
If multiple lens groups move during zooming, then the zoom ratio is increased, but the device complexity increases
Solution Approach 1:
The patent divides the projection optical system into nine distinct lens groups (G1-G9) with specific powers and functions. This segmentation allows each group to be optimized for its role in the zoom mechanism, with the first lens group (negative power) and ninth lens group (positive power) remaining fixed while the intermediate groups move during zooming, achieving high zoom ratio with controlled complexity.
Solution Approach 2:
The patent implements a dynamic zoom mechanism where seven lens groups (G2-G8) move along the optical axis during zooming operations. This dynamic arrangement allows the focal length to be continuously adjusted from wide-angle to telephoto, achieving a zoom ratio of 2.50 or more while maintaining a compact structure by having only the necessary groups move rather than the entire lens assembly.
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 high zoom ratio and compact total lens length while ensuring sufficient resolution performance across the entire zoom range, simplifying the lens barrel structure and improving optical performance by effectively correcting aberrations.
Implementation Method 1
The first lens group has negative power and includes one first aspherical lens. Any one of the second lens group, the third lens group, the fourth lens group, the fifth lens group, the sixth lens group, the seventh lens group, the eighth lens group, and the ninth lens group includes at least one second aspherical lens.
Data Source
AI summary
A projection optical system includes: a first lens group; a second lens group; a third lens group; a fourth lens group; a fifth lens group; a sixth lens group; a seventh lens group; an eighth lens group; and a ninth lens group, and these lens groups are in an order from a magnification side to a reduction side. The projection optical system includes an aperture stop disposed between the second lens group and the eighth lens group. The first lens group has negative power and includes one first aspherical lens. Any one of the second lens group, the third lens group, the fourth lens group, the fifth lens group, the sixth lens group, the seventh lens group, the eighth lens group, and the ninth lens group includes at least one second aspherical lens. During zooming, the first lens group and the ninth lens group are fixed, and the second lens group, the third lens group, the fourth lens group, the fifth lens group, the sixth lens group, the seventh lens group, and the eighth lens group move.