Immersion Microscope Objective Lens NA 1.25 Near-Infrared Correction
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Solution Overview
Problem
Conventional microscope objective lenses have insufficient numerical aperture and inadequate chromatic aberration correction in the near-infrared wavelength range, particularly for fluorescence observation and optical tweezers applications.
Innovation Solution
An immersion-type microscope objective lens design comprising a first lens group with positive refractive power, a second lens group with achromatic lenses, and a third lens group with negative refractive power, optimized with specific refractive index and Abbe number ratios, and surface power conditions to achieve high numerical aperture (NA=1.25) and excellent chromatic aberration correction from visible light to near-infrared wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional objective lens design is used, then chromatic aberration correction is achieved, but numerical aperture is insufficient
Solution Approach 1:
The objective lens is divided into multiple lens groups (first lens group G1 with positive refractive power, second lens group G2 with negative refractive power, and third lens group G3 with positive refractive power). Each group contains specific lens elements with defined refractive indices and Abbe numbers that work together to simultaneously achieve high numerical aperture (1.25) and excellent chromatic aberration correction across visible and near-infrared wavelengths.
Solution Approach 2:
The patent employs composite lens design using materials with different optical properties. Specific glass materials are selected for each lens element based on their refractive index (nd) and Abbe number (νd) characteristics. For example, the first lens group uses materials with nd≥2.0 and νd≤50, while the third lens group uses materials with 1.80≤nd≤2.20 and 30≤νd≤70, creating a composite optical system that achieves both high NA and chromatic correction.
2Illumination intensity
If high numerical aperture is achieved, then observation brightness and resolution are improved, but chromatic aberration correction becomes inadequate
Solution Approach 1:
Different regions of the optical system are assigned different material properties to address local optical requirements. The first lens group (G1) near the object uses high refractive index materials (nd≥2.0) for strong light gathering, the second lens group (G2) uses materials with specific Abbe numbers for chromatic correction, and the third lens group (G3) uses materials with 1.80≤nd≤2.20 and 30≤νd≤70 for final image quality optimization. This local optimization of material properties enables simultaneous achievement of high brightness and chromatic correction.
3Manufacturing precision
If chromatic aberration correction is optimized for visible light, then visible light performance is improved, but near-infrared correction becomes insufficient
Solution Approach 1:
The objective lens is designed with multi-functionality to serve both visible light fluorescence observation and near-infrared applications including two-photon microscopy and optical tweezers. The lens groups are configured with specific refractive index and Abbe number combinations that provide excellent chromatic aberration correction across a broad spectrum from visible to near-infrared wavelengths, making the same lens suitable for multiple different wavelength ranges and applications.
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 design effectively corrects various aberrations across a broad wavelength range, enabling high-resolution, bright observation images with a numerical aperture of 1.25 and excellent chromatic aberration correction from visible light to near-infrared wavelengths.
Implementation Method 1
each of which includes a positive lens and a negative lens... Pt=(nd−nt)/(ng−nd)... ΔPt3/Δνd3 satisfying the following conditional expression: 0.0035≦ΔPt3/Δνd3≦0.0062
Implementation Method 2
a first lens group having positive refractive power; a second lens group having positive refractive power; and a third lens group having negative refractive power
Data Source
AI summary
An immersion type microscope objective lens OL includes, in order from a cover plate C side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 includes at least one cemented lens. The second lens group G2 includes at least two achromatic lenses. The third lens group G3 includes, in order from the object side, an achromatic lens CL31 having a strong concave surface facing an image side, and an achromatic lens CL32 having a strong concave surface facing the object side.