VPH grating technology for the Thirty Meter Telescope instrumentation program
Bibliographic record
Abstract
Volume Phase Holographic Gratings (VPHG) provide unique advantages over traditional dispersive elements and are being considered for instruments on many large telescopes, including the Wide Field Optical Spectrograph (WFOS) for the Thirty Meter Telescope (TMT). In this paper we review the properties of VPHG particularly with regard to their use in large multi-object spectrographs such as WFOS. Design considerations include optimal sizes and working angles, and variations in blaze efficiencies as a function of grating and field angles. For instruments like WFOS, a gratings mosaic is a promising solution to meet the size requirements. The methodologies of mosaics and the required tolerances are evaluated. VPH gratings may also be used in echelette mode with significant advantages, although more lab tests should be carried out to explore and optimize performance. A brief status report on the VPHG development activities in the Goodman lab is included, with a plan for future development.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.015 | 0.005 |
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".