Measurement of rotated Janus particle’s position and orientation in the optical trap
Bibliographic record
Abstract
Optical tweezers are precise tools for translating and rotating micrometer-sized particles and are used widely in biology and physics. In a linearly polarized optical trap, Janus particles comprising two hemispheres with different refractive indexes can be rotated about the beam axis following the polarization direction. In previous research, the position and orientation of a Janus particle relative to the polarization direction were simulated using the T-matrix method, whereas this paper is focused on accurate experimental measurements. The position and orientation of a Janus particle are extracted by image processing, and the polarization direction is controlled by a motor-driven half-wave plate (HWP). The particle’s orientation and the polarization direction are related via the HWP’s rotation angle. However, rotating the HWP not only rotates the polarization direction but also causes the trap center to fluctuate positionally because of the inevitable misalignment between the HWP’s rotation axis and the optical axis. Both the trap center and the polarization direction affect the particle’s position, but the influence of the former is removed with the aid of a homogeneous microsphere. The experimental results show that the Janus particle rotates following the polarization direction to keep the interface between its two hemispheres always parallel to the polarization direction. Also, the particle’s centroid moves in a circular orbit around the trap center to hold the trap center in the hemisphere with the higher refractive index. The experimental results agree with the previous simulation results and are of use for future applications.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".