Diode Laser Beam Profile Evaluation for Flow Cytometry
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Solution Overview
Problem
Semiconductor laser diodes with non-Gaussian beam shapes pose challenges in flow cytometry due to their poor beam quality and variability in emission spectra, despite meeting standard specifications, necessitating improved characterization methods to assess their suitability for use in flow cytometers.
Innovation Solution
A method and device for evaluating diode laser performance by receiving laser beam profiles, determining specific beam widths at different intensities, computing ratios to assess deviation from a Gaussian beam shape, and determining suitability for use in flow cytometry, which includes a beam profiler, heat sink, and processor for optical alignment and evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If semiconductor laser diodes are used as excitation sources in flow cytometry, then cost and lifetime are improved, but beam quality and beam shape become poor
Solution Approach 1:
The patent changes the evaluation parameters from standard laser specifications (M2, divergence, beam waist) to intensity-dependent beam width ratios measured at multiple intensity levels. This parameter transformation enables detection of non-Gaussian beam shapes that standard single-point measurements miss, thereby resolving the contradiction by finding a new measurement approach that works with the actual laser diode output characteristics.
2Device complexity
If standard laser specifications (M2, divergence, beam waist) are used for evaluation, then manufacturing and measurement are simplified, but beam shape variability and emission spectra variability are not detected
Solution Approach 1:
The patent segments the beam width measurement into multiple intensity levels (first, second, and third intensity levels) rather than using a single measurement point. By computing ratios of beam widths at different intensity levels, the method creates a multi-dimensional evaluation that detects non-Gaussian profiles while maintaining measurement feasibility through systematic segmentation of the intensity range.
Solution Approach 2:
The patent adds an intensity dimension to the beam width measurement by evaluating beam width at multiple intensity levels rather than a single point. This dimensional expansion transforms the evaluation from a scalar measurement to a multi-level assessment, enabling detection of beam shape variability that single-point measurements cannot capture.
3Measurement precision
If laser alignment optimization is repeated, then alignment precision is improved, but beam shape variability and emission spectra variability persist
Solution Approach 1:
The patent performs preliminary evaluation of beam shape characteristics using intensity-dependent width ratios before final alignment optimization. By assessing the beam profile structure in advance through ratio calculations at multiple intensity levels, the method identifies lasers with inherently poor beam shapes early in the evaluation process, preventing wasted effort on alignment optimization that cannot fix fundamental beam shape defects.
Data Source
AI summary
Methods for evaluating performance a diode laser are provided. In embodiments, methods include receiving a laser beam profile of a diode laser, determining first, second and third laser beam widths at first, second and third laser intensities, respectively, for the laser beam profile, computing a first ratio between the second and third laser beam widths, computing a second ratio between the first and second laser beam widths, evaluating laser performance based on the first and second ratios, and outputting a determination regarding the suitability of the laser for use in a flow cytometry setting. Devices for practicing the subject methods are also provided, and include first and second stages configured to receive a diode laser and beam profiler, respectively. Aspects of the invention further include flow cytometers incorporating a diode laser that has been evaluated by the subject method.