Impact of laser guide star fratricide on TMT MCAO system
Bibliographic record
Abstract
Laser beams projected from the ground to form laser guide stars (LGS) experience scattering and absorption that reduce their intensity as they propagate through the atmosphere. Some fraction of the scattered light will be collected by the other LGS wavefront sensors and causes additional background in parts of the pupil. This cross-talk is referred to as the fratricide effect. In this paper we quantify the magnitude of four different sources of scattering/absorption and back scattering, and evaluate their impact on performance with various zenith angles and turbulence profiles for the Thirty Meter Telescope (TMT) MCAO system, NFIRAOS. The resulting wavefront error is on the order of 5 to 20 nm RMS, provided that the mean background from the fratricide can be calibrated and subtracted with an accuracy of 80%. We have also found that the impact of fratricide is a weak function of LGS asterism radius.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| 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".