Wide-Angle Optical Layout With Stationary Field Curvature Correction
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Solution Overview
Problem
Wide-angle imaging optical systems face challenges with aberration fluctuation, such as field curvature aberration and astigmatism, during focus adjustment, leading to degraded optical performance, and existing focus mechanisms are either heavy or require multiple moving lens groups.
Innovation Solution
An optical system with a configuration that includes a first positive lens group and a negative lens group moving in the optical axis direction, while a second positive lens group remains stationary, facilitating easier focus adjustment and reducing the size and weight of the focus mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple focus groups are used to reduce aberration fluctuation during focusing, then optical performance is improved, but the weight and complexity of the focus mechanism increases
Solution Approach 1:
The optical system is divided into three distinct lens groups with specific functions: the first positive lens group (G1) handles focusing, the second positive lens group (G2) corrects field curvature aberration, and the negative lens group (G3) provides overall optical power. This segmentation allows each group to be optimized for its specific function, reducing the need for heavy actuators on multiple groups.
Solution Approach 2:
The field curvature correction function is extracted from the focusing mechanism and assigned to the stationary second positive lens group (G2). This separation means that focusing operations on G1 do not need to simultaneously manage field curvature correction, reducing the complexity and weight of the focusing actuator while maintaining optical performance through the dedicated correction group.
2Adaptability or versatility
If the field of view is made wider-angle, then wide-angle projection capability is improved, but aberration fluctuation during focus adjustment increases
Solution Approach 1:
Different regions of the optical system are assigned different optical properties: the first positive lens group (G1) has positive refractive power for focusing, the second positive lens group (G2) has positive refractive power specifically positioned to correct field curvature at the intermediate image plane, and the negative lens group (G3) has negative refractive power for overall power control. This local differentiation of optical properties allows wide-angle performance while controlling aberrations in their respective zones.
Solution Approach 2:
The second positive lens group (G2) acts as an intermediary between the focusing group (G1) and the negative power group (G3), specifically positioned at the intermediate image plane to correct field curvature aberration. This intermediary group mediates the aberration introduction from focusing operations and the wide-angle geometry, providing localized correction that enables both wide-angle capability and stable aberration performance.
3Ease of operation
If focus adjustment is performed by moving lens groups, then focusing function is achieved, but the center of gravity shifts and operation complexity increases
Solution Approach 1:
The optical system uses an asymmetric configuration where only the first positive lens group (G1) moves for focusing operations, while the second positive lens group (G2) remains stationary at the intermediate image plane and the negative lens group (G3) has a different movement pattern. This asymmetric arrangement simplifies the focusing mechanism compared to symmetric multi-group movement, reducing operational complexity while maintaining effective focus control.
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 enables efficient focus adjustment with reduced aberration fluctuation and lighter focus mechanisms, improving optical performance and ease of operation.
Implementation Method 1
a first positive lens group (G1) including a plurality of lens elements and positioned on a magnification side with respect to an intermediate imaging position; a second positive lens group (G2) including a plurality of lens elements and positioned between the first positive lens group (G1) and the intermediate imaging position
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3C
AI summary
The present disclosure is directed to an optical system internally having an intermediate imaging position MI that is conjugate with both of a magnification conjugate point on a magnification side and a reduction conjugate point on a reduction side, the optical system including: a first positive lens group GP1 including a plurality of lens elements and positioned on the magnification side with respect to the intermediate imaging position; a second positive lens group GP2 including a plurality of lens elements and positioned between the first positive lens group GP1 and the intermediate imaging position M1; and a negative lens group GN including a plurality of lens elements and positioned on the reduction side with respect to the intermediate imaging position MI, wherein, during focusing, the first positive lens group GP1 and the negative lens group GN move in an optical axis direction, and the second positive lens group GP2 is stationary.