Catadioptric Optical System Aberration Control
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Solution Overview
Problem
Existing optical systems for imaging and projecting apparatuses face challenges in achieving high resolution over a wide field angle while maintaining a small size, as they often require complex and costly spherical lenses or struggle with aberration correction, especially when trying to keep the f-number low.
Innovation Solution
The optical system comprises a front group with a refractive surface convex toward the enlargement side and a rear group with a concave reflective surface, where specific curvature radius and distance ratios are maintained to satisfy conditional expressions, allowing for effective aberration correction and a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a spherical lens is used to correct on-axis aberration, then on-axis aberration such as spherical aberration and axial chromatic aberration can be corrected favorably, but the imaging plane becomes spherical requiring a spherical imaging device or display device, leading to increased complexity and size
Solution Approach 1:
The patent replaces the spherical imaging device requirement with a planar imaging device by substituting the spherical lens system with a catadioptric system comprising a meniscus lens and a reflective surface. This substitution allows the light flux to be reflected and redirected to form an image on a planar surface, eliminating the need for complex spherical imaging devices while maintaining aberration correction capabilities
Solution Approach 2:
The patent employs a composite optical system combining refractive elements (meniscus lens with specific curvature ratios) and reflective elements (reflective surface). This composite approach integrates the advantages of both lens and mirror systems to achieve aberration correction with a planar imaging plane, resolving the contradiction between correction quality and device simplicity
2Area of stationary object
If a catadioptric lens with a concave inner reflective surface is used to achieve a wide field angle, then a wide field angle can be realized, but it is difficult to favorably correct aberration while keeping the f-number low
Solution Approach 1:
The patent optimizes specific geometric parameters of the meniscus lens, particularly the curvature radius ratios (0.7 < |R1|/L1 < 1.5 and 2 < |Rm|/Lm < 7), to achieve a balance between wide field angle and aberration correction. By carefully controlling these parameter ranges, the system achieves both wide field coverage and acceptable aberration levels with a low f-number
3Measurement precision
If existing optical systems are designed to achieve high resolution over a wide field angle, then high resolution can be achieved, but the system size increases and complexity increases leading to higher costs
Solution Approach 1:
The patent divides the optical system into distinct functional segments: a front meniscus lens for light collection and initial aberration control, an aperture diaphragm for light flux control, and a rear reflective surface for image formation. This segmentation allows each component to be optimized independently for its specific function, achieving high resolution with reduced overall complexity compared to monolithic optical systems
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 enables high-resolution imaging over a wide field angle with a small and cost-effective optical system, reducing the complexity and size of imaging and projecting apparatuses while maintaining low f-numbers, thus enhancing optical performance.
Implementation Method 1
a front group (1), an aperture diaphragm (3), and a rear group (2) in this order from an object side, the front group (1) having a refractive surface (11a)
Implementation Method 2
the rear group (2) having a reflective surface (12b) on which a light flux reflected at the reflective surface (12b) forms an image
Data Source
AI summary
An optical system 10 includes, in order from an enlargement side, a front group 1, an aperture diaphragm 3, and a rear group 2, the front group 1 including a refractive surface 11a convex toward the enlargement side, the rear group 2 including a concave reflective surface 12b, and Conditional Expressions of 0.7≤|Rl|/Ll≤1.5 and 2≤|Rm|/Lm≤7 are satisfied, where a curvature radius of the refractive surface 11a is Rl (mm), a distance between the refractive surface 11a and the aperture diaphragm 3 is Ll (mm), a curvature radius of the reflective surface 12b is Rm (mm), and a distance between the aperture diaphragm 3 and the reflective surface 12b is Lm (mm).