Microscope Objective Lens Diffractive Element Placement
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Solution Overview
Problem
Microscope objective lenses face challenges in balancing on-axis and off-axis chromatic aberrations while maintaining a long working distance, particularly when using diffractive optical elements, as the arrangement of these elements needs to be optimized to correct aberrations effectively.
Innovation Solution
A microscope objective lens configuration is proposed, including a first lens group with positive refractive power and a second lens group with negative refractive power, where the diffractive optical element is positioned closer to the image than the maximum diameter of the light flux passing through the first lens group, with specific conditions on the ratios of focal lengths and diameters to ensure effective aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the focal length of the lens group is increased to secure a long working distance, then the working distance is improved, but the space for arrangement of lenses is limited and correction of aberrations becomes difficult
Solution Approach 1:
The patent replaces part of the traditional refractive lens system with a diffractive optical element. The diffractive optical element is introduced to correct chromatic aberration, allowing the lens system to achieve both long working distance and effective aberration correction without requiring excessive lens complexity. The diffractive element provides a different mechanism for aberration correction compared to traditional refractive lenses.
Solution Approach 2:
The patent employs a composite optical system combining refractive lenses and a diffractive optical element. This composite approach leverages the advantages of both refractive and diffractive optics to simultaneously achieve long working distance and effective aberration correction. The combination allows for optimized performance that neither component could achieve alone.
2Manufacturing precision
If a diffractive optical element is used to correct chromatic aberration, then chromatic aberration correction is improved, but on-axis and off-axis chromatic aberrations need to be balanced which requires optimized arrangement
Solution Approach 1:
The patent specifies precise parameter relationships for the diffractive optical element arrangement. Condition (1) defines the ratio between the maximum diameter of light flux passing through the first lens group and the maximum diameter of light flux passing through the diffractive optical surface. Condition (2) defines the ratio between the focal length of the second lens group and the focal length of the entire system. These parameter optimizations enable balanced correction of on-axis and off-axis chromatic aberrations.
Solution Approach 2:
The patent introduces different lens groups with specific refractive powers positioned at different locations. The first lens group has positive refractive power and the second lens group has negative refractive power, creating localized regions with different optical characteristics. This local differentiation enables targeted correction of different types of aberrations in different regions of the optical path.
3Manufacturing precision
If the diffractive optical element is arranged closer to the image, then aberration correction is improved, but the arrangement position must be precisely controlled
Solution Approach 1:
The patent establishes specific parameter conditions that define the optimal arrangement position. Condition (1) specifies the ratio relationship between diameters of light flux at different locations, and condition (2) specifies the focal length ratio relationship. These parameter definitions provide clear criteria for positioning the diffractive optical element, transforming the positioning requirement from a vague precision control problem into a solvable parameter optimization problem.
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 sufficiently corrects both on-axis and off-axis chromatic aberrations while maintaining a long working distance, enhancing the imaging performance by optimizing the placement and characteristics of the diffractive optical element within the lens system.
Implementation Method 1
a diffractive optical element including a diffractive optical surface
Implementation Method 2
a first lens group with positive refractive power; and a second lens group with negative refractive power
Data Source
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AI summary
Provided is a microscope objective lens that sufficiently corrects on-axis and off-axis chromatic aberrations and that has a long working distance. A microscope objective lens OL includes, in order from an object side, a first lens group G1 with positive refractive power and a second lens group G2 with negative refractive power. The first lens group G1 of the microscope objective lens OL includes a diffractive optical element GD including a diffractive optical surface D, and the diffractive optical element GD is arranged at a position closer to the image than a section where a diameter of a light flux passing through the first lens group G1 is the largest.