Immersion Microscope Objective Lens Configuration for High NA and Long Working Distance
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Solution Overview
Problem
Traditional fluorescent microscopy techniques face limitations in observing living specimens due to high burdens from dyeing and restricted observation targets, with existing immersion microscope objectives struggling to balance numerical aperture and working distance while maintaining optical performance.
Innovation Solution
The development of an immersion microscope objective with a specific lens configuration, including a first lens group with a plano-convex and meniscus lens, a second lens group with three-piece cemented lenses, and a third lens group with a Gaussian type structure, optimized to achieve a high numerical aperture, long working distance, and wide field of view, while correcting aberrations across visible and near-infrared light ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the numerical aperture is increased to improve imaging brightness and resolution, then the working distance decreases, limiting observation capability
Solution Approach 1:
The objective lens is divided into multiple lens groups (first lens group with positive refractive power, second lens group with positive refractive power, and third lens group with negative refractive power). Each group is optimized for specific functions: the first group provides high numerical aperture for brightness, the second group corrects aberrations, and the third group extends working distance, collectively resolving the contradiction between numerical aperture and working distance.
Solution Approach 2:
Different lens groups are assigned different refractive powers and optical properties tailored to their specific roles. The first lens group uses high refractive index materials (n1≥1.7) to maximize light gathering, while the third lens group uses negative refractive power to extend working distance, allowing each part to optimize its local function without compromising overall performance.
2Measurement precision
If fluorescent dye is used to enhance observation of living body specimens, then the burden and damage to the specimen increases
Solution Approach 1:
The objective lens is designed to operate across a broad spectral range from visible light to near-infrared wavelengths. This enables the use of fluorescent proteins that emit in the near-infrared region, which penetrate living tissue more effectively and cause less phototoxicity compared to traditional visible light fluorescent dyes, thereby reducing specimen damage while maintaining observation precision.
3Device complexity
If a simple lens structure is used to reduce manufacturing complexity, then aberration correction performance deteriorates
Solution Approach 1:
The complex aberration correction requirements are divided among multiple specialized lens groups. The first lens group focuses on achieving high numerical aperture with controlled spherical aberration, the second lens group addresses chromatic and spherical aberrations through three-piece cemented lenses, and the third lens group corrects field curvature and astigmatism. This segmentation allows each group to be optimized for its specific correction task, achieving high manufacturing precision without requiring an overly complex monolithic structure.
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 bright and clear fluorescent imaging with a large numerical aperture and long working distance, effectively observing living specimens with reduced damage, and supports applications in confocal and two-photon excitation microscopy.
Implementation Method 1
a first lens group having a positive refractive power, including a cemented lens composed of a plano-convex lens whose plane surface faces the object side and a meniscus lens whose concave surface faces the object side
Implementation Method 2
Fluorescent observation is a method for observing a specimen by applying excitation light to a living body specimen to which a tag is attached by fluorescent dye and detecting fluorescent light generated from the fluorescent dye
Data Source
AI summary
An immersion microscope objective comprises, in order from an object side, a first lens group having a positive refractive power comprising a cemented lens composed of a plano-convex lens whose plane surface faces the object side and a meniscus lens whose concave surface faces the object side, and at least one single lens having a positive refractive power; a second lens group having a positive refractive power comprising a three-piece cemented lens; and a third lens group having a negative refractive power including a Gaussian type lens structure, wherein the objective satisfies the following conditions when n1, NAob, d0 and β are a refractive index at a d-line of the single lens having the highest refractive index included in the first lens group, a numerical aperture on the object side of the objective, a working distance of the objective, and a magnification of the objective, respectively.1.7≦n10.75≦NAob≦1.450.4≦NAob*d0≦30.03≦NAob/β≦0.1.