Microscope Objective Lens Diffractive Element Aberration Correction
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Solution Overview
Problem
Conventional microscope objective lenses face challenges in correcting coma aberration at large angles of view and achieving high image performance across the visual field, particularly when using diffractive optical elements.
Innovation Solution
A microscope objective lens configuration comprising a first lens group with a positive refractive power, a second lens group including a diffractive optical element with diffractive grating grooves on bonded surfaces of different optical materials, and a third lens group with achromatic components, optimized by specific focal length and refractive index conditions to effectively correct chromatic aberration and maintain image quality across the field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a diffractive optical element is used to correct chromatic aberration, then the number of cemented lenses can be reduced, but coma aberration correction at large angles of view becomes difficult
Solution Approach 1:
The patent combines a diffractive optical element with a specific lens group configuration (positive first group, positive second group, negative third group) to merge the advantages of both diffractive and refractive optics. This hybrid approach maintains chromatic aberration correction while improving coma aberration performance through the coordinated action of multiple optical elements.
Solution Approach 2:
The patent applies different optical properties to different parts of the system: the diffractive optical element handles chromatic aberration correction, while the specific lens surfaces (particularly the concave image-side surface of the third group) address coma aberration. Each component is optimized for its specific function rather than trying to make a single element do everything.
2Manufacturing precision
If conventional cemented lenses and anomalous dispersion glass are used to correct chromatic aberration, then image quality is improved, but the lens system becomes expensive
Solution Approach 1:
The patent replaces expensive anomalous dispersion glass materials with a diffractive optical element that can be manufactured more economically. The diffractive structure achieves chromatic aberration correction through its periodic pattern rather than relying on rare and costly glass compositions, making the system more affordable while maintaining performance.
Solution Approach 2:
The patent substitutes material-based chromatic correction (using special glass materials with specific dispersion properties) with a structural approach (diffractive optical element with specific grating patterns). This replaces the need for expensive anomalous dispersion glass with a manufacturable diffractive structure that achieves the same optical effect.
3Area of stationary object
If the visual field range is expanded, then more of the specimen can be observed, but image performance in the periphery deteriorates
Solution Approach 1:
The patent optimizes different regions of the optical system for different functions: the lens groups and diffractive element work together to correct aberrations at the center, while the specific configuration of the third lens group with its concave image-side surface addresses peripheral coma aberration. This localized optimization allows the entire field to maintain high performance.
Solution Approach 2:
The patent uses a dynamic combination of optical elements where the diffractive optical element and the three lens groups work together in a coordinated manner. The specific focal length relationships (f12/f and f3/f) create a balanced system that maintains aberration correction across the entire visual field, from center to periphery.
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 configuration ensures sufficient correction of chromatic aberration and other aberrations, providing a wide visual field with improved image performance and manufacturing efficiency.
Implementation Method 1
a diffractive optical element that joins two diffractive element components respectively made from different optical materials and which has a diffractive optical surface on which diffractive grating grooves are formed
Implementation Method 2
a first lens group having a positive refractive power, a second lens group, and a third lens group having a negative refractive power
Data Source
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AI summary
A microscope objective lens OL comprises, in order from the object side: a first lens group G1 having a positive refractive power, a second lens group G2, and a third lens group G3 having a negative refractive power, wherein the first lens group G1 includes a positive lens component L1 having a lens surface with a negative refractive power and at least one cemented lens component CL11 having a positive refractive power, the second lens group G2 includes a diffractive optical element GD that joins two diffractive element components L6 and L7 respectively made from different optical materials and which has a diffractive optical surface D on which diffractive grating grooves are formed on the bonded surface of the two diffractive element components, and at least one cemented lens component CL21, and the third lens group G3 includes at least one achromatic lens component CL31 and a lens surface of the third lens group G3 nearest to the image side is arranged so that a concave surface of the lens surface faces the image side.