Compact Imaging Lens System Using Free-Form Prism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional imaging lens systems for wide-angle applications face challenges in correcting off-axis and color aberrations while maintaining a compact size, ease of machining, and low cost, due to the complexity of free-form surface prisms and the need for multiple lens elements.
Innovation Solution
A compact imaging lens system comprising a first biconcave lens, a free-form surface prism with aspheric surfaces, and a biconvex or concave-convex second lens, where the prism rotates the optical axis by 90 degrees, reducing system length and volume, and using injection molded plastic lenses to lower production costs and simplify assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional spherical ground glass lenses are used, then material availability and color aberration correction are improved, but spherical aberration and astigmatic aberration correction becomes difficult in small F-number and large wide angle applications
Solution Approach 1:
The patent employs aspheric lens surfaces instead of conventional spherical surfaces. The aspheric surfaces are defined by mathematical equations with multiple coefficients that allow precise control of the surface curvature at different zones, enabling effective correction of spherical aberration and astigmatic aberration while maintaining manufacturability through injection molding processes.
2Manufacturing precision
If aspheric glass lens elements are used to correct aberrations, then image quality and barrel distortion reduction are improved, but machining difficulty and system cost increase
Solution Approach 1:
The patent replaces expensive and difficult-to-machine aspheric glass lens elements with aspheric plastic lens elements made through injection molding. This substitution significantly reduces manufacturing cost and machining difficulty while maintaining the aberration correction capabilities provided by the aspheric surfaces, making the solution economically viable for mass production.
3Manufacturing precision
If multiple lens elements are used to correct off-axis aberrations and color aberrations in wide angle applications, then aberration correction is improved, but system length, volume and cost increase
Solution Approach 1:
The patent designs each lens element to perform multiple functions simultaneously. The aspheric surfaces of the lens elements are optimized to correct spherical aberration, astigmatic aberration, off-axis aberrations, and color aberrations all at once, rather than requiring separate dedicated elements for each type of aberration correction. This multi-functional design reduces the total number of elements needed while maintaining comprehensive aberration correction.
4Length of moving object
If free-form surface prisms are used to reduce system length, then optical path folding is improved, but construction complexity and machining difficulty increase
Solution Approach 1:
The patent combines the functions of multiple optical components into a single integrated free-form surface prism. The prism simultaneously performs optical path folding, aberration correction, and field of view expansion functions that would traditionally require separate elements. This integration reduces the total number of components, simplifies assembly, and decreases overall system complexity while achieving the desired compact form factor.
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 high image resolution with reduced size and weight, simplified assembly, and lower production costs by employing a free-form surface prism and aspheric plastic lenses, effectively correcting aberrations and aligning with the compact trend in image pick-up devices.
Implementation Method 1
The above-mentioned prism type design folds the optical path by 90 degrees by means of a 45° reflecting mirror
Implementation Method 2
aspheric glass or plastic lenses have been introduced to help reduce these aberrations
Implementation Method 3
For a wide-angle lens system, important design considerations include correction of off-axis aberrations and color aberrations associated with a wide angle of view
Data Source
AI summary
A compact imaging lens system includes, in order from the object side to the image side, a first lens (1) of negative refractive power, a free-form surface prism (2) of positive refractive power and a second lens (3) of positive refractive power. The free-form surface prism has an incidence surface (S3), a reflection surface (S4) and an exit surface (S5). The first lens is disposed on the side of the incidence surface, and the second lens is disposed on the side of the exit surface. The free-form surface prism functions equivalent to a right-angle prism with aspheric surfaces.