Double exposure ESPI for non-contact photoacoustic tomography
Bibliographic record
Abstract
We have developed an apparatus for fast and non-contact assessment of photoacoustic signals from tissue-simulating media. The apparatus was based on electronic speckle pattern interferometry (ESPI), which in our case featured a Mach- Zehnder interferometer, a 532-nm probe laser, and a double exposure CMOS camera to record the holographic speckles that originated from the surface of a tissue-mimicking phantom. The double exposure camera enabled high speed recording of the speckle patterns at MHz timescales. The speckle patterns were reconstructed into phase and out-of-plane displacement maps of the phantom surface. Experiments were performed with an agarose phantom that contained a 1 cm diameter embedded spherical absorber 2 cm below the detection surface. Exposure of the phantom to a pulsed laser at 1064 nm resulted in photoacoustic waves from the absorber that were detectable at the surface of the phantom. Repeated laser exposure with increasing delay times between the two camera exposures enabled spatial-temporal sampling of the displacement maps. The results show the apparatus could identify the position and size of the photoacoustic source relative to the detection surface. Future work will investigate reconstruction of photoacoustic images from the recorded displacement maps.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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".