Double-Pyramid Wavefront Sensors: Tolerance Relaxation and Cheaper Alternatives using Achromatic Double-Roof Prisms
Bibliographic record
Abstract
We present the current design of the double-pyramid planned for the TMT-NFIRAOS Visible Natural Guide Star WFS and its manufacture challenges to meet all the requirements in terms of tip size, pupil image quality and mapping on the detector pixels. We show that the angular tolerance of the pyramid can be relaxed from 6 arcsec. to 2 arcmin. without significant impact on the AO performance, which is within the capabilities of most optical suppliers and reduces the fabrication cost by a factor 10 or more. Then we compare the pyramid design to a new concept using two double-roof prisms, optically equivalent to an achromatic double-pyramid and offering very similar performance. Roof prisms are easier to manufacture to tolerance than pyramids since there is no tip. We also present an adjustable version of the achromatic double-roof prism allowing very fine adjustments of the positions of the four pupils onto the detector pixels, which can relax the manufacture tolerance of the prisms even more.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 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".