Edge Emitting Laser Line Source for Raman Spectroscopy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Raman spectroscopy systems face challenges in producing high aspect ratio illumination with minimal astigmatism and spectral full width at half maximum (FWHM), particularly with edge emitting lasers which generate strongly diverging beams with high astigmatism and large spectral FWHM, limiting their effectiveness in microbiological testing and sampling applications.
Innovation Solution
An apparatus and method utilizing an astigmatic beam from an edge emitting laser, corrected by an aspherical lens to produce high aspect ratio illumination with a diffraction grating to reduce spectral FWHM, ensuring the beam is collimated with different foci in orthogonal directions to achieve astigmatism-corrected and monochromatic light for improved microscopy and spectroscopy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If an edge emitting laser is used to generate a high aspect ratio beam, then the beam aspect ratio is improved, but the astigmatism and spectral FWHM increase
Solution Approach 1:
The patent divides the beam correction process into separate functional stages: first correcting astigmatism using an aspherical lens, then shaping the beam into a line using cylindrical lenses. This segmentation allows each optical element to be optimized for its specific function without compromising the other.
Solution Approach 2:
The aspherical lens serves as an intermediary element between the edge emitting laser and the subsequent cylindrical lenses. It specifically corrects the astigmatism introduced by the laser, producing a beam with minimal astigmatism that can then be effectively shaped into a line illumination pattern.
2Shape
If an edge emitting laser is used to produce line illumination, then the illumination aspect ratio is improved, but the spectral FWHM increases
Solution Approach 1:
The optical system is segmented into distinct functional components: the aspherical lens for astigmatism correction, cylindrical lenses for line formation, and a diffraction grating for spectral filtering. This segmentation allows each component to address a specific parameter independently.
Solution Approach 2:
The diffraction grating acts as an intermediary element that selectively filters the laser beam spectrum. It allows only the desired wavelength range to pass through, reducing the spectral FWHM while preserving the high aspect ratio line illumination geometry established by the preceding optical elements.
3Device complexity
If conventional circular illumination is used, then the light source design is simplified, but the resolution for microbiological detection is reduced
Solution Approach 1:
The illumination system is segmented into functional stages that transform circular light into line illumination: aspherical lens for astigmatism correction, cylindrical lenses for line formation, and diffraction grating for spectral control. This segmentation enables precise control over the illumination geometry for improved microbial detection.
Solution Approach 2:
The system transitions from two-dimensional circular illumination to one-dimensional line illumination by introducing cylindrical lenses that collapse the beam in one dimension while maintaining the other. This dimensional transformation provides the high aspect ratio illumination needed for improved resolution in microbiological detection 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 solution provides high aspect ratio illumination with reduced astigmatism and spectral FWHM, enhancing the resolution and accuracy of Raman spectroscopy for biological and chemical detection, particularly suitable for microbiological testing and sampling applications.
Implementation Method 1
an aspherical lens arranged to compensate the astigmatism of the astigmatic beam... with a finite focal length in the direction of the largest beam divergence angle β effective to collimate light with the largest beam divergence angle β and has a finite focal length in the direction of the smallest beam divergence angle α effective to collimate light with the smallest beam divergence angle α
Implementation Method 2
a diffraction grating arranged respective to the laser to provide feedback reducing a spectral full width at half maximum (FWHM) of the astigmatic beam
Implementation Method 3
a laser generating an astigmatic beam having astigmatism tan(β)/tan(α), where β is largest divergence angle of the astigmatic beam and α is the smallest divergence angle of the astigmatic beam
Data Source
Figure 1~2
AI summary
An apparatus comprises: a microscope objective focused on a microscope field of view; a light source including a laser generating an astigmatic beam and optics configured to couple the astigmatic beam into the microscope objective to produce high aspect ratio illumination at the microscope field of view; and a data acquisition system configured to generate data pertaining to light emanating from the microscope field of view responsive to the high aspect ratio illumination. The apparatus may be a Raman spectroscopy system. The laser may be an edge emitting laser. The optics of the light source may include an aspherical lens arranged to compensate the astigmatism of the astigmatic beam. The optics of the light source may include a diffraction grating arranged respective to the laser to provide feedback reducing a spectral full width at half maximum (FWHM) of the astigmatic beam.