Immersion Microscope Objective with Cemented Triplet Lens Groups
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Solution Overview
Problem
Conventional microscope objectives with a numerical aperture of about 1.0 struggle to achieve high image plane flatness and resolution, especially for 40-fold magnification, and are inadequate for fluorescence observation with short-wavelength excitation light.
Innovation Solution
An immersion microscope objective with a numerical aperture ranging from 1.35 to 1.5, comprising a five-group configuration including a first cemented lens with a planoconvex and meniscus lens, a second and third cemented triplet lens, a fourth cemented lens with a meniscus shape, and a fifth lens with a concave surface, optimized to correct Petzval sum, chromatic aberrations, coma, and astigmatism through specific refractive index and focal length relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the numerical aperture is increased to improve resolution, then the resolution is improved, but the image plane flatness deteriorates
Solution Approach 1:
The objective lens is divided into five distinct lens groups (first through fifth lens groups) with specific configurations. Each group contains carefully designed cemented lenses and individual lenses that work together to independently control different aspects of aberration correction, allowing simultaneous optimization of resolution and image plane flatness at high numerical aperture (1.35-1.5).
Solution Approach 2:
Different regions of the optical system are assigned specific functions: the first lens group (with positive refractive power) primarily corrects spherical aberration, the second and third lens groups (cemented triplets) correct chromatic aberrations, the fourth lens group (meniscus shape) corrects coma, and the fifth lens group corrects astigmatism. This localized functional assignment enables comprehensive aberration control while maintaining high NA.
2Measurement precision
If the numerical aperture is increased to improve resolution, then the resolution is improved, but the complexity of the optical system increases
Solution Approach 1:
Multiple lens elements are combined into cemented lens assemblies (first cemented lens, first cemented triplet lens, second cemented triplet lens, second cemented lens) to reduce the total number of air-glass interfaces and simplify the optical system. The cemented triplets integrate three lens elements into single functional units that correct multiple types of aberrations simultaneously, reducing overall system complexity while maintaining high numerical aperture (1.35-1.5) and excellent image quality.
3Adaptability or versatility
If the numerical aperture is increased to enable fluorescence observation, then the observation capability is improved, but the aberration correction becomes more difficult
Solution Approach 1:
The optical system employs composite lens designs with different glass materials having specific refractive indices and Abbe numbers. The cemented lenses and triplets are constructed from combinations of positive and negative lenses made from different glass types, enabling simultaneous correction of chromatic aberrations across multiple wavelengths (including short-wavelength excitation light for fluorescence) and other monochromatic aberrations at high numerical aperture (1.35-1.5).
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 objective provides high image plane flatness and resolution, effectively correcting aberrations and maintaining high numerical aperture, suitable for 40-fold magnification and fluorescence observation.
Implementation Method 1
a first lens group that has a positive refractive power and includes a first cemented lens, the first cemented lens consisting of a planoconvex lens having a plane surface facing an object and a meniscus lens having a concave surface facing the object
Data Source
AI summary
An immersion microscope objective includes: a first lens group that has a positive refractive power and includes a first cemented lens consisting of a planoconvex lens having a plane surface facing an object and a meniscus lens having a concave surface facing the object; a second lens group that includes a first cemented triplet lens; a third lens group that includes a second cemented triplet lens; a fourth lens group that includes a second cemented lens with a meniscus shape having a concave surface facing an image; and a fifth lens group that includes a lens having a concave surface facing the object, wherein the immersion microscope objective has a numerical aperture within a range from 1.35 to 1.5. The first and second cemented triplet lenses each consist of a positive lens, a negative lens, and a positive lens.