High Aperture Immersion Objective for Confocal Microscopy
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Solution Overview
Problem
Existing high-aperture immersion objectives for confocal microscopy using oil as an immersion liquid face limitations in achieving apochromatic correction across a wide spectral range and maintaining parfocality, especially in the UV range, with numerical apertures being capped at 1.2 and lacking transparency beyond 365 nm.
Innovation Solution
A high-aperture immersion objective composed of three optical subsystems, featuring cemented elements, collecting lenses made of fluoro-crown glass, diverging lenses from highly-refractive lanthanum glass, and meniscuses with specific refractive properties, enabling apochromatic correction from 365 to 900 nm with numerical apertures of 1.3 to 1.4 and an object field of 0.4 to 0.625 mm, while maintaining transparency up to 340 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If water is used as the immersion medium, then the objective can achieve apochromatic correction in a wide wavelength range, but the numerical aperture is limited to about 1.2
Solution Approach 1:
The patent changes the immersion medium from water to oil, fundamentally altering the refractive index parameter. This enables the objective to achieve numerical apertures of 1.3 to 1.4 while maintaining apochromatic correction across the 365-900 nm wavelength range, resolving the contradiction between immersion medium adaptability and measurement precision.
2Measurement precision
If oil immersion is used to increase numerical aperture, then resolution capability improves, but parfocality is not achieved in the UV range from 400 nm to 365 nm
Solution Approach 1:
The patent employs composite lens designs combining multiple glass types (fluoro-crown glass, lanthanum glass, short flint glass) with specific refractive indices and dispersion properties. This composite approach enables simultaneous optimization for UV parfocality and high numerical aperture oil immersion performance, achieving both 1.3-1.4 NA and correct parfocality across 365-900 nm.
Solution Approach 2:
Different regions of the optical system use specialized lens elements with locally optimized properties. The objective incorporates specific meniscus lenses and cemented elements with tailored refractive powers in critical UV paths, while other regions optimize for visible and infrared performance, enabling simultaneous UV parfocality and high-resolution capability.
3Measurement precision
If the objective is designed for high numerical aperture, then resolution improves, but the object field size is reduced
Solution Approach 1:
The patent divides the optical system into three distinct subsystems, each optimized for specific functions. This segmentation allows the objective to achieve high numerical aperture (1.3-1.4) for resolution while maintaining a relatively large object field diameter of 0.4 to 0.625 mm, as each subsystem contributes differently to the overall optical performance.
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 solution achieves apochromatic correction across a broad spectral range with high-resolution numerical apertures and large object fields, ensuring excellent transparency and parfocality, thereby enhancing the performance of confocal microscopy applications.
Implementation Method 1
the cemented element comprises a flat surface facing the object side and consists of a collecting lens and a meniscus that is curved toward the object side, the meniscus having a negative refractive power
Implementation Method 2
the collecting lens of the first optical member of the second subsystem out of fluorspar (CaF2) or a fluoro-crown glass
Implementation Method 3
Known immersion objectives that use water as known solutions have the disadvantage that the numerical aperture is limited to about 1.2. However, higher numerical apertures and thereby a higher resolution capability require an oil immersion as a necessity.
Data Source
AI summary
The invention relates to a high aperture immersion objective particularly for uses in confocal microscopes where oil is the immersion fluid, which objective is composed of three lenses and/or subsystems comprising lens groups. An apochromatic correction in a range from 365 to 900 nm is achieved at high resolving numeric apertures of 1.3 to 1.4 and an object field from 0.4 to 0.625 mm by the specification of the optical components. Additionally, the immersion objective has sufficiently good transparency up to a wavelength of 340 nm.