Multiaxis applications of a cryogenic range-resolved laser interferometer
Bibliographic record
Abstract
A range-resolved laser interferometer is the leading candidate for providing displacement metrology that can meet the stringent precision and low power dissipation requirements of cryogenic space astronomy missions. In prior work, a three-phase homodyne laser interferometer was developed using a simple optical and signal processing scheme that achieved the desired dynamic performance required for state-of-the-art cryogenic far-infrared spectrometers, however, the system required three detectors and amplifiers, and exhibited poor performance at low speeds due to 1/f noise associated with the detector and electronics.1,2 A frequency modulation continuous wave (FMCW) heterodyne approach was subsequently adopted to address this shortcoming by shifting the signal of interest well away from the 1/f region.1,3 This technique provides the additional advantage of enabling simultaneous multiaxis measurements all using a single laser and a single detector. This paper discusses several applications of the multiaxis FMCW design that as currently implemented can provide simultaneous measurements of up to 8 axes. The need for a precise and intrinsically low power 1-D displacement metrology system to measure the optical path difference of a cryogenic Fourier transform spectrometer was the initial driver for this research; applications in N-dimensions are currently being explored. Several applications of the technique at both high and low speeds are considered, including multiaxis precision linear positioning, the simultaneous measurement of the cryogenic coefficients of thermal expansion for multiple materials, and cryogenic accelerometry. Results from these applications will be presented and used to discuss limitations of the technique.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".