Gouy phase shift in Fourier-domain optical coherence tomography
Bibliographic record
Abstract
A Gouy phase shift is acquired each time a beam goes through a focal point. It is a common practice in optical coherence tomography (OCT) systems to focus the light on a sample to obtain a good transverse resolution in addition to the axial resolution provided by the coherence gating. In presence of chromatic aberration, the position of the focal point is wavelength dependent. This leads to an enhanced wavelength dependency of the Gouy phase shift for measurements performed in the focal region of the sample arm. This affects the positioning of the envelope of the interferogram and can thus have a strong impact on the axial position accuracy as measured by an OCT system using the maximum of the envelope. Chromatic aberration not only leads to a Gouy phase shift, but also to an additional wavelength-dependent term related to the transverse phase distribution over the aperture of the collecting optics. This last term brings a contribution that is of the same order as the Gouy phase shift. We demonstrated these effects in time-domain OCT in a previous paper [Lamouche et al., Optics Comm., Vol. 239, 297 (2005)]. This problem is revisited with Fourier-domain OCT by performing measurements with a swept-source OCT system. This allows to confirm that the effect observed is not interferometer dependent but purely optical in origin. It also provides a clear experimental confirmation that the effect is related to chromatic aberration. This work is of interest for OCT measurements that require accurate relative position measurements in the focal region.
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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 | 0.002 | 0.009 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 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".