UIST: Engineering: Grism Wheels 2004-2005
UIST has two 9-slot grism wheels which contain the polarimetry prism and the grisms for spectroscopy. The table below lists the grism wheel populations.
FILTERS: See the UIST filter-wheels web page for cut-on/cut-off wavelengths for the filters. Note that the short-/long- grisms are used in second order, so some of the blocking filter choices are driven by the need to block different orders (e.g. 2nd order lines between 1.34-1.51 passed by the B2 would appear in the short-K grism in 3rd order [at 2.00-2.26], so the short-K cutoff must be >1.51um; similarly, 2nd order lines between 1.58-1.67 would come through the HK filter and be seen by long-K in 3rd order [at 2.37-2.51], so the long-K blocker cut-off must be >1.67um).
WEIGHTS: These are for the grism AND the holder. The holders alone (with screws, clips, etc.) each weigh 124.2g.
REF: The refence number is etched onto the grism and the grism holder. The full reference number is 30a##m, e.g. for the short J the code is 30a54m.
9 March 2004 — 1 May 2005
| Wheel 1 | Wheel 2 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Posn | Grism | Ref. | Weight | Blocker | Posn | Grism | Ref. | Weight | Blocker | ||
| 1 | open | — | — | — | 1 | open | — | — | — | ||
| 2 | Short J | 54 | 242.4 | J-spectral | 2 | Empty | — | — | — | ||
| 3 | Wollaston | 81 | 225 | — | 3 | Long J | 53 | 250 | J-spectral | ||
| 4 | Short L | 59 | 217.4 | L-spectral | 4 | HK | 83 | 181.4 | B2 (cgs4) | ||
| 5 | blank | — | 221.7 | — | 5 | Short K | 56 | 250 | HK-spectral | ||
| 6 | KL | 57 | 205 | KL-spectral | 6 | Long H | 51 | 241.2 | H-spectral | ||
| 7 | Short H | 52 | 250 | H-spectral | 7 | Empty | — | — | — | ||
| 8 | Long K | 55 | 251.4 | KL-spectral | 8 | Long L | 58 | 235 | L-spectral | ||
| 9 | HK x-disp | 86 | 159.5 | none | 9 | M | 60 | 230 | M-spectral |
Movement between positions 5 or 6 and the other positions involves moving passed a datum switch.
History
9 March 2004: The new zeiss grisms (below) were found to be faulty (poor throughput). These were removed today for return to Zeiss. Posns 2 and 7 were left vacant (i.e. holder installed but with no grism or blank).
1 March 2003: New HK low and IJ grisms (Zeiss – direct ruled infrarsill) were installed. These replaced hyperfine grisms that were found to be faulty.
Previous grism wheel arrangements: Pre-20040309. Pre-20030301.