Projection Optical System with Single Aspherical Lens
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Solution Overview
Problem
Existing projection optical systems face challenges in achieving a compact total lens length while maintaining high zoom ratios and effectively correcting various aberrations, particularly due to manufacturing accuracy issues with aspherical lenses.
Innovation Solution
A projection optical system comprising multiple spherical lens groups with a fixed first lens group and moving lens groups during zooming, including an aperture stop between specific lens groups to correct aberrations, and utilizing only one aspherical lens to minimize manufacturing accuracy-related issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If multiple aspherical lenses are used to correct aberrations and achieve compact total lens length, then the total lens length is reduced and aberration correction is improved, but manufacturing accuracy deteriorates due to cumulative errors from multiple aspherical lenses
Solution Approach 1:
The patent extracts the aspherical surface requirement from multiple lens elements and concentrates it into a single lens element. Specifically, only the first lens element has an aspherical surface, while all other lens elements have spherical surfaces. This extraction approach maintains the aberration correction benefits of aspherical lenses while eliminating the cumulative manufacturing errors that would result from using multiple aspherical lenses.
Solution Approach 2:
The patent changes the parameter of aspherical surface distribution from multiple lens elements to a single lens element. By modifying the spatial distribution parameter of aspherical surfaces (from 2 or more locations to 1 location), the system achieves compact total lens length while improving manufacturing precision by reducing the number of aspherical surfaces that require high-precision manufacturing.
2Adaptability or versatility
If more lens groups are made movable to achieve higher zoom ratio, then the zoom ratio is improved, but the device complexity increases
Solution Approach 1:
The patent segments the lens system into nine distinct lens groups with specific functional assignments. The first and ninth lens groups are fixed, while the second through eighth lens groups are movable. This segmentation allows the system to achieve high zoom ratio through coordinated movement of seven lens groups while maintaining manageable structural complexity through clear functional division.
Solution Approach 2:
The movable lens groups (second through eighth) serve multiple functions: they enable zooming operations, correct various optical aberrations, and maintain focus across the zoom range. By designing these lens groups to perform multiple functions simultaneously, the patent achieves high zoom ratio without proportionally increasing device complexity.
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 higher zoom ratio with a shorter total lens length while effectively correcting aberrations, simplifying the lens barrel structure and ensuring telecentricity on the reduction side, thus improving image quality and compactness.
Implementation Method 1
The first lens group has negative power and includes one aspherical lens. Each 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 only a spherical lens.
Data Source
AI summary
A projection optical system includes: first lens group; second lens group; third lens group; fourth lens group; fifth lens group; sixth lens group; seventh lens group; eighth lens group; ninth lens group; and an aperture stop disposed between second and eighth lens groups, and these lens groups are in an order from magnification side to reduction side. The first lens group has negative power and includes one aspherical lens. Each of the second lens group, third lens group, fourth lens group, fifth lens group, sixth lens group, seventh lens group, eighth lens group, and ninth lens group includes only a spherical 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.