Fixed-Focus Projection Lens Aberration Control
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Solution Overview
Problem
Conventional projector lenses face a trade-off between achieving high image quality and low distortion, which requires multiple lenses, leading to bulkiness and increased weight, contradicting the trend of miniaturization.
Innovation Solution
A fixed-focus projection lens design comprising six lenses, including a negative meniscus, biconvex, biconcave, and meniscus lenses, with specific refractive powers and aspherical surfaces, arranged to minimize volume and weight while maintaining high image quality and low distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If more than ten lenses are used for compensation, then image quality and distortion are improved, but the projector becomes bulky and heavy
Solution Approach 1:
The patent applies parameter changes by using aspherical surfaces instead of traditional spherical surfaces in the lens design. This fundamental change in the geometric parameter of the lens surfaces enables high image quality correction with fewer lens elements. The aspherical surfaces provide better aberration correction capabilities, allowing the system to achieve the required optical performance with only six lenses rather than ten or more.
Solution Approach 2:
Each lens element in the six-element design is designed to perform multiple optical functions simultaneously. For example, the lenses are configured with specific refractive powers and aspherical surface combinations that allow them to correct multiple types of aberrations (spherical, coma, astigmatism, field curvature) while also providing the required focal length and image formation. This multi-functionality reduces the need for additional specialized correction lenses.
2Manufacturing precision
If more than ten lenses are used for compensation, then distortion is reduced, but the projector becomes bulky and heavy
Solution Approach 1:
The patent uses aspherical surface parameters to achieve superior distortion control. The aspherical surfaces provide enhanced control over light ray paths, enabling precise correction of distortion aberrations. This parameter change from spherical to aspherical surfaces allows effective distortion compensation with fewer lens elements, directly reducing the overall weight of the projection lens assembly.
Solution Approach 2:
The patent employs composite lens structures where different lens elements with specific refractive indices and aspherical surface profiles are combined. The third and fourth lenses are adhered together to form a doublet, creating a composite optical element that achieves complex aberration correction functions. This composite approach allows distortion control without requiring additional separate correction lenses, thereby reducing weight.
3Manufacturing precision
If lenses with greater processing difficulty are used, then image quality is improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies precise aspherical surface parameters that, while providing high image quality, are designed to be manufacturable using modern optical fabrication techniques. The aspherical surfaces are defined with specific mathematical parameters that balance optical performance with manufacturing feasibility. This controlled approach to parameter specification allows high-quality imaging while maintaining reasonable manufacturing standards.
Solution Approach 2:
The patent combines multiple lens elements into adhesive bonded doublets (third and fourth lenses adhered together). This merging reduces the total number of separate optical components that need to be individually manufactured, aligned, and assembled. The adhesive bonding process is a well-established manufacturing technique that simplifies assembly compared to traditional mechanical mounting, thereby improving ease of manufacture while maintaining optical performance.
4Volume of moving object
If a six-lens design is used, then the projector is miniaturized, but achieving high image quality becomes more difficult
Solution Approach 1:
The patent achieves high image quality in a compact six-lens design through the use of aspherical surface parameters. The aspherical surfaces provide enhanced aberration correction capabilities that allow the system to maintain high optical performance with fewer elements. The specific aspherical parameters are optimized to correct spherical aberration, coma, and other distortions that would otherwise require additional lens elements in a conventional spherical design.
Solution Approach 2:
The patent uses composite lens structures, particularly the adhesive-bonded doublet of third and fourth lenses, to achieve complex optical functions within the limited six-element configuration. This composite approach allows a single optical subsystem to perform multiple correction functions, enabling high image quality in a miniaturized design. The different refractive indices and aspherical profiles of the bonded lenses work together to correct various aberrations simultaneously.
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 design achieves high image quality and low distortion with a reduced number of lenses, resulting in a miniaturized and lightweight projector that is easier to manufacture and assemble, effectively addressing the bulkiness and weight issues of conventional lenses.
Implementation Method 1
at least one surface of the first lens is aspherical; at least one surface of the sixth lens is aspherical
Implementation Method 2
The second lens is a biconvex lens with a positive refractive power. The third lens has a negative refractive power. The fourth lens has a positive refractive power
Data Source
AI summary
A fixed-focus projection lens, in order from an image side to an image source side along an optical axis, includes a first lens with negative refractive power, a second lens with positive refractive power, a third lens with negative refractive power, a fourth lens with positive refractive power, a fifth lens with positive refractive power, and a sixth lens with positive refractive power. The second lens is a biconvex lens. While projecting, a light enters the fixed-focus projection lens from the image source side, and passes through the fixed-focus projection lens. Further more, at least one surface of the first lens is aspherical, a refractive index of the second lens is greater than 1.8, and a refractive index of the fifth lens is greater than 1.7. Such arrangement helps to lower a spherical aberration of spherical lens, shortening the optical system, and effectively lower the distortion.