Laser Beam Shaping Optics for Uniform Flow Cell Illumination
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Solution Overview
Problem
Existing optical systems for fluorescent analysis of flow cells suffer from measurement errors and inefficiencies in illuminating biological samples with laser light.
Innovation Solution
The system employs a combination of lasers emitting different wavelengths, a beam combiner, and a series of optical elements including polychroic filters and cylindrical lenses to produce coaxial or offset beams with flat-top distributions, which are then expanded and directed through a telecentric lens system for precise illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple lasers with different wavelengths are combined and directed through a complex optical assembly with polychroic filters and cylindrical lenses, then illumination uniformity and measurement precision are improved, but device complexity increases
Solution Approach 1:
The optical system is divided into separate functional modules: a beam combiner for merging multiple laser wavelengths, a polychroic filter for wavelength-specific beam separation, and cylindrical lenses for beam shaping. Each module performs a specific function, allowing for optimized performance while maintaining manageable complexity through functional decomposition.
Solution Approach 2:
A telecentric lens system is introduced as an intermediary between the laser assembly and the flow cell. This telecentric lens ensures that light rays enter the flow cell at uniform angles, eliminating perspective errors and improving illumination uniformity across the sample area, thereby enhancing measurement precision without requiring direct complex positioning of multiple lasers.
2Illumination intensity
If a complex optical assembly with multiple surfaces and polychroic filters is used to separate and shape laser beams, then illumination uniformity is improved, but device complexity increases
Solution Approach 1:
Cylindrical lenses are employed to create a flat-top beam profile by redistributing the laser light intensity locally across the beam cross-section. This transforms the natural Gaussian intensity distribution into a uniform flat-top distribution, ensuring even illumination across the flow cell sample area while maintaining a relatively simple optical configuration.
Solution Approach 2:
The polychroic filter serves multiple functions: it separates different laser wavelengths, directs each wavelength through appropriate optical paths, and enables the system to handle multiple laser sources simultaneously. This multi-functionality reduces the need for separate optical components for each wavelength, thereby managing device complexity while achieving uniform illumination.
3Device complexity
If laser beams are focused directly without beam shaping, then device complexity is reduced, but measurement precision deteriorates due to non-uniform illumination and speckle
Solution Approach 1:
The beam profile parameter is transformed from a natural Gaussian distribution to a flat-top distribution using cylindrical lenses. This parameter change in the light intensity distribution ensures uniform illumination across the sample, reducing measurement errors and improving precision while adding only moderate optical components.
Solution Approach 2:
A telecentric lens system is introduced as an intermediary to modify the convergence properties of the laser beams. The telecentric lens ensures that all light rays are parallel to the optical axis at the sample plane, eliminating perspective distortion and improving measurement precision without requiring overly complex beam delivery systems.
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 enhances the accuracy and efficiency of optical analysis by reducing speckle and ensuring uniform illumination, thereby improving measurement precision and reducing errors.
Implementation Method 1
a second surface that can be configured to transmit the first light of the first wavelength along a first optical path and to reflect the second light of the second wavelength along a second optical path
Implementation Method 2
a second surface that can be configured to reflect the second light of the second wavelength along a second optical path
Implementation Method 3
a first surface that can be configured to receive the combined beam of light and to transmit the first light of the first wavelength and the second light of the second wavelength
Implementation Method 4
The cylindrical lens array can be configured to alter a distribution of light of the first beam to output a first substantially flat-top distribution of light, and to alter a distribution of light of the second beam to output a second substantially flat-top distribution of light
Implementation Method 5
The objective lens system can be configured to output a first flat-top output line of the first wavelength at a sample plane, and to output a second flat-top output line of the second wavelength at the sample plane
Data Source
AI summary
Various embodiments of a laser illumination system are disclosed. In some examples, a system includes one or more lasers and a beam combiner configured to direct a combined light beam along a path. The system can include a polychroic optical assembly that receives the combined light beam and to output a first beam of the first light of the first wavelength and a second beam of the second light of the second wavelength. The second beam can be offset from the first beam. The polychroic optical assembly can be a prism assembly. The system can include one or more optical elements configured alter a distribution of light of the first beam to output a first output line at a sample plane, and to alter a distribution of light of the second beam to output a second output line at the sample plane.