High energy laser pulse coupling in a multimode fiber for photoacoustic tomography
Bibliographic record
Abstract
In traditional photoacoustic tomography, external illumination is used to excite acoustic waves. However, with the assistance of fibre-transmitted light, multidirectional illumination or internal illumination can be achieved which can obtain a better image at a deeper depth. Laser pulses delivered by fibre are energy-limited by the fibre core size and damage threshold. To increase the amplitude of photoacoustic waves and their penetration, it is necessary to improve the fibre coupling energy and efficiency. To improve the coupling performance of single fibres, we use a cylindrical lens array to homogenize the incident beam before a coupling lens. Simulation in Zemax shows that this approach flattens the beam profile on the front surface of the fibre, decreasing the risk of fibre damage. Experimental results with fibre core diameters of 1mm and 1.5mm show that both types of fibre can output more than 50mJ energy per pulse at 700nm wavelength. The coupling efficiency is measured to be above 70% and even reaches 90% as the wavelength changes from 675nm to 900nm. This improvement of coupling energy in single fibres will benefit photoacoustic tomography applications using internal illumination.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".