Wide-Angle Optical System Lens Diameter Reduction
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Solution Overview
Problem
Existing wide-angle image-formation optical systems with a half angle of view of 90° or greater face challenges in reducing the size and cost while minimizing the number of lenses, as they often suffer from increased lens diameter and aberrations due to the need for stronger negative refracting power, leading to higher fabrication costs and longer system lengths.
Innovation Solution
The optical system comprises a first negative lens, a second meniscus lens concave on its object side, an aperture stop, and a lens group with positive refracting power, where the entrance pupil is positioned in front by configuring the lens group of negative refracting power as a single lens, and the positive lens is strategically placed near the image side to balance telecentric capability and correct aberrations, adhering to specific conditions to optimize lens diameters and system length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the power of the lens group having negative refracting power is strengthened to achieve a half angle of view of 90° or greater, then the half angle of view is improved, but the optical effective diameter of the first lens grows large leading to increased fabrication cost and system size
Solution Approach 1:
The lens group with negative refracting power is divided into multiple lenses (first lens and second lens) arranged in sequence. This segmentation allows the negative refracting power to be distributed across multiple elements rather than concentrated in a single large lens, thereby reducing the optical effective diameter of the first lens while achieving the required half angle of view of 90° or greater
Solution Approach 2:
The second lens is specifically designed as a meniscus lens with its concave surface facing the object side, creating local optical properties that help control the chief ray angles and reduce the required diameter of the first lens. This localized design optimization enables the system to achieve wide angle of view without proportionally increasing the first lens diameter
2Manufacturing precision
If multiple negative lenses are used to reduce aberrations in the front group, then aberration correction is improved, but the whole length of the optical system increases
Solution Approach 1:
The aperture stop is positioned between the two negative lenses (first and second lenses) of the front group with negative refracting power. This merging of the stop with the negative lens group allows for effective aberration correction through the interaction of the two negative lenses while preventing the system length from increasing proportionally, as the stop serves dual purposes of aperture control and aberration management
3Ease of manufacture
If the number of lenses is reduced to lower fabrication cost, then manufacturing cost is improved, but aberration correction becomes more difficult
Solution Approach 1:
The second lens serves multiple functions: it contributes to the negative refracting power of the front group, helps correct aberrations through its meniscus shape with concave object-side surface, and works in conjunction with the aperture stop positioned between the negative lenses. This multi-functionality allows effective aberration correction with a limited number of lenses, reducing fabrication cost while maintaining optical quality
Solution Approach 2:
The second lens is specifically designed as a meniscus lens with its concave surface facing the object side, creating specific optical parameters that enable effective aberration correction. By changing the shape parameter (meniscus configuration) and positioning it with the aperture stop between the negative lenses, the system achieves good aberration control with fewer total lenses, thereby reducing manufacturing cost
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 configuration results in a compact, low-cost optical system with reduced lens diameter and effective aberration correction, enabling a wide-angle view while maintaining a compact form factor, suitable for applications like onboard cameras.
Implementation Method 1
a first lens L1 that is a negative lens, a second lens L2 that is a meniscus lens concave on its object side
Implementation Method 2
a lens group that has positive refracting power
Data Source
AI summary
The invention relates to a compact image-formation optical system that is diminished in a diametrical direction with as few lenses as possible while well adapting to an wide-angle arrangement having a half angle of 90° or greater, and an imaging system incorporating the same. The image-formation optical system comprises, in order from its object side, a first lens L1 that is a negative lens, a second lens L2 that is a meniscus lens concave on its object side, an apertures stop S, and a lens group G having positive refracting power.