Table 3
Differential dispersion and length characteristics of the GRAVITY fiber chains at 240 K and for zero extension of the FDDLs.
| Channel | Telescope | Beam | Differential length (m) | Differential dispersion (µrad cm2) | Min–max contrast (%) |
|---|---|---|---|---|---|
| FT | 4 | A | 0 | 0 | 99.8–100.0 |
| 3 | B | 1.90 | 0.3 | 99.7–100.0 | |
| 2 | C | −0.27 | −1.1 | 99.7–100.0 | |
| 1 | D | 0.69 | −1.2 | 99.7–100.0 | |
| SC | 4 | E | 0 | 0 | 99.4–100.0 |
| 1 | F | 1.48 | 2.04 | 99.4–100.0 | |
| 2 | G | −0.81 | 1.94 | 99.4–100.0 | |
| 3 | H | −0.43 | 0.35 | 99.6–100.0 | |
Notes. No error bars are given for the differential dispersion measurements but the minimum value measured with the setup is of the order of 0.1 µrad cm2, which gives an idea of the accuracy of the method. The ranges of fringe contrasts in the last column are deduced from these values and obtained by pairing a fiber with the fibers of closest or most different measured differential dispersion in a given channel. The fringe contrast is given for the lowest resolution of GRAVITY (λ/δλ ≃ 22).
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