Achromatic Anamorphic Objective for Multi-Wavelength Flow Cytometry
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Solution Overview
Problem
Designing a focusing objective for flow cytometry that can effectively combine four or more laser radiation wavelengths in a common focal plane is complex and costly, often requiring multiple optical materials and cemented doublet or triplet elements, which can be problematic with ultraviolet wavelengths.
Innovation Solution
An anamorphic objective with two cylindrical lenses and a rotationally-symmetric lens is used to project collimated coaxial laser beams with different wavelengths, focusing them to the same beam-waist width in one direction and different locations in another direction, creating a common beam-width in the working plane without cemented elements, utilizing astigmatism to achieve this.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional achromatic or apochromatic objectives are used to focus multiple laser wavelengths, then the number of wavelengths that can be focused in a common focal plane increases, but the device complexity and cost increase significantly
Solution Approach 1:
The objective is divided into separate optical elements: a first lens for focusing in the first transverse direction and a second lens for focusing in the second transverse direction. This segmentation allows each lens to be optimized for its specific function, reducing the need for complex cemented doublets or triplets while still achieving multi-wavelength focusing capability
Solution Approach 2:
The patent introduces astigmatism to intentionally create different focal positions in the two transverse directions. By accepting and utilizing this dimensional difference rather than eliminating it, the system can focus multiple wavelengths in a common focal plane using simpler optical elements, as the astigmatic focus allows each wavelength to be focused at the same position in the first transverse direction while having different focal positions in the second transverse direction
2Adaptability or versatility
If cemented doublet or triplet elements are used in the objective, then the ability to focus multiple wavelengths improves, but reliability decreases due to UV radiation degradation of optical cements
Solution Approach 1:
The patent extracts and eliminates the cemented elements from the optical system. By using separate air-spaced lenses instead of cemented doublets or triplets, the system achieves multi-wavelength focusing capability without the reliability issues associated with UV degradation of optical cements
Solution Approach 2:
Air serves as an intermediary medium between the optical elements, replacing the cement that would otherwise bond the lenses together. This air spacing eliminates the UV degradation problem while still allowing the optical system to function as intended
3Adaptability or versatility
If more optical elements with different spectral dispersion are added to the objective, then the number of focusable wavelengths increases, but manufacturing cost increases
Solution Approach 1:
Each lens in the system performs multiple functions: the first lens focuses all wavelengths in the first transverse direction, and the second lens focuses all wavelengths in the second transverse direction. This multi-functionality reduces the total number of optical elements needed compared to conventional designs, lowering manufacturing costs while maintaining multi-wavelength capability
Solution Approach 2:
The patent changes the approach from using multiple optical elements with different spectral dispersion properties to using astigmatism with fewer elements. By changing the focusing parameter strategy and accepting astigmatic focus, the system achieves multi-wavelength capability with simpler, less expensive optical elements
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 allows for a simple and cost-effective focusing objective that is insensitive to beam parameter fluctuations, capable of focusing multiple wavelengths in a common focal plane with reduced material complexity and no cemented elements, maintaining beam quality and stability.
Implementation Method 1
An objective is provided including a first cylindrical lens-element, a second cylindrical lens-element, and a rotationally-symmetric lens-element. The objective is arranged such that, in a first transverse direction of the objective, the laser-beams are each focused to a beam-waist located about in the working-plane and having about the same beam-waist width. In a second transverse direction of the objective, the laser-beams are focused to beam-waists at different locations that are displaced from the working-plane.
Implementation Method 2
An anamorphic objective with two cylindrical lenses and a rotationally-symmetric lens is used to project collimated coaxial laser beams with different wavelengths, focusing them to the same beam-waist width in one direction and different locations in another direction, creating a common beam-width in the working plane without cemented elements, utilizing astigmatism to achieve this.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An anamorphic three-element objective lens projects a plurality of beams of different wavelengths and different diameters into an elongated focal spot in a working- plane. In one transverse direction of the lens, the beams are tightly focused with equal beam-waist widths in the working-plane, defining a height of the focal spot. In another transverse direction, the different beams are focused progressively beyond the working- plane such that the beams have a common beam-width in the working-plane, thereby defining a width of the focal spot.