These are MMTF scans through somewhat more than 1 free spectral range, using a neon lamp and the 6600/260 blocking filter, at a range of different etalon spacings (Z coarse settings). They are provided to aid in line identification, and to demonstrate the issues with order overlap when the FSR is smaller than the width of the blocking filter.
Because the lines repeat themselves from order to order, when the FSR is smaller than the passband of the blocking filter, lines can appear to be out of sequence. For example, if the FSR is 200 A, the Ne 6507 line can appear at a wavelength that you expect to be "6707". Spectra toward the bottom of this page (higher etalon spacing, higher order, lower FSR) show this.
Note that because the lamp and optical setup used in lab testing were different from the IMACS internal lamp, and the 6600 A blocking filter has been recoated in the interim, relative intensities of neon lines at IMACS may be different from these plots, but the wavelength pattern should be similar. Note that 6402 A is a very bright neon line which is leaking through the tail of the 6600/260 filter; its intensity may be rather different than shown in the plots below.
Values of order, FSR, dw/dz from bench testing:
# zc=zcoarse, all at 6600 A, wavelengths in A # #zc zfine dwdz fsr fwhm order-num # -3 3.00 0.536 375 18 17.6 -2 0.20 0.469 325 15 20.3 -1 0.20 0.413 285 13 23.2 0 0.20 0.361 248 9.7 26.6 1 0.20 0.33 226 8.9 28.9 2 0.20 0.294 202 9 32.7 3 0.20 0.268 185 7.9 35.7 4 0.20 0.251 173 6.7 38.2 4 9.99 0.236 163 5.9 40.5
The x-axis of the following plots is CS-100 z setting. The FSR of the etalon is about 690 in z at 6600 A (independent of order).
Front panel Z was -3, 3.00. The lines are Ne 6599, 6678, 6717, 6402, 6507, 6533, 6599, 6678.
Front panel Z was --2, 0.20. The lines are Ne 6599, 6678, 6717, 6507, 6533, 6599, 6678.
Front panel Z was -1, 0.20. The lines are Ne 6599, 6678, 6717, 6507, 6533, 6599.
Front panel Z was +0, 0.20. The lines are Ne 6533, 6599, 6402, 6678, 6717, 6507, 6533, 6599.
Front panel Z was +1, 0.20. The lines are Ne 6599, 6402, 6678, 6717, 6507, 6533, 6599, 6402.
Front panel Z was +2, 0.20. The lines are Ne 6599, 6678, 6717+6507, 6533, 6599.
Front panel Z was +3, 0.20. The lines are Ne 6402, 6599, 6678, 6507, 6533+6717, 6402, 6599.
Front panel Z was +3, 9.99. The lines are Ne 6402, 6599, 6678+6507, 6533, 6717, 6402, 6599.
Benjamin Weiner, bjw at as.arizona.edu, 15 Nov 2006