Immersion Objective Lens Design for High Numerical Aperture Aberration Correction
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Solution Overview
Problem
Conventional microscope objectives with high numerical apertures face challenges in achieving a numerical aperture of 1.42 or higher while effectively correcting spherical and chromatic aberrations without specific immersion media.
Innovation Solution
The design incorporates a first lens group with a plano-convex and meniscus lens, a second lens group with multiple cemented lenses, and a third lens group with specific cemented and meniscus lenses, satisfying conditional expressions to achieve a high numerical aperture of 1.42 or higher and correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional high numerical aperture objectives are used, then the numerical aperture can be increased, but spherical and chromatic aberrations cannot be effectively corrected without specific immersion media
Solution Approach 1:
The objective lens is divided into multiple lens groups (first, second, and third lens groups) with different refractive powers and configurations. Each group contributes to correcting specific types of aberrations while maintaining the high numerical aperture, allowing independent optimization of each segment's function.
Solution Approach 2:
The patent employs multiple cemented lenses within the lens groups, combining different glass materials with varying refractive indices and dispersion properties. This composite approach enables simultaneous correction of spherical and chromatic aberrations while achieving the target numerical aperture of 1.42 or higher.
2Measurement precision
If the numerical aperture is increased to 1.42 or higher, then imaging resolution is improved, but the complexity of lens configuration increases
Solution Approach 1:
Different lens groups are assigned specific functions: the first lens group with positive refractive power addresses certain aberrations, the second lens group with positive refractive power handles other correction needs, and the third lens group with negative refractive power completes the aberration correction. This localized functional assignment simplifies the overall design complexity.
Solution Approach 2:
The patent optimizes specific parameters including the conditional expression 3.5 ≤ (H/f) × NAob ≤ 5.2, where H is the maximum height of axial marginal ray, f is focal length, and NAob is numerical aperture. By controlling these parameters within specific ranges, the design achieves high numerical aperture while managing complexity through quantitative constraints.
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 allows for a high numerical aperture of 1.42 or higher while effectively correcting aberrations, enabling wide-field, high-resolution observations with bright and high-contrast imaging.
Implementation Method 1
a first lens group that has a positive refractive power; a second lens group that has a positive refractive power; and a third lens group that has a negative refractive power
Data Source
AI summary
An immersion objective has a numerical aperture of 1.42 or higher, and includes in order from the object side a positive first lens group, a positive second lens group, and a negative third lens group. The first lens group includes a first cemented lens that includes a plano-convex lens and a first meniscus lens, and a positive lens. The second lens group includes a plurality of cemented lenses. The third lens group includes in order from the object side a second cemented lens that includes a positive lens and a negative lens, a negative lens that has a concave surface facing the object side, and a positive lens. When H is a maximum height of an axial marginal ray, f is a focal length of the objective, and NAob is the numerical aperture, the objective satisfies a conditional expression below3.5≤(H/f)×NAob≤5.2 (1).