The original user's manual was written with the "classical" beam combination table in mind, which was the first
application of the NICMOS3 detector.
In May 1998 work was started to incorporate our NICMOS3 dewar into the FLUOR experiment, and culminated in June 1999 with the additional upgrade in FLOUR to a new control system based on a faster computer (G3) and a piezo scanner (180 um mechanical stroke).
As far as the NICMOS3 detector is concerned, the basic idea is that the G3 replaces the Quadra when operating with FLUOR. That is, the Pentium is still responsible for the data acquisition, and sends the data to the G3 for display and storage. However, the G3 does more than the Quadra because it also sets the readout mode (through a GUI) and controls the fast scanner (also the short delay line, but that is irrelevant here).
From the data acquisition point of view, the basic difference between the FLUOR and "classical" modes is that in FLUOR 4, instead of 2, pixels are sampled.
Custom Pentium software was written to do this, and to communicate with the G3, and therefore the location of Pentium executables is different. Typically they are in a C:>fluor/ directory. There is still a "q_read" program used for alignment, and a "fringes7" program used for fringe sampling. The coordinates of the 4 pixels to be sampled are still specified in a "fringes7.cfg" file. When the Pentium starts, it now displays a message telling the user how to get to the FLUOR and "classical" data acquisition programs.
The G3 GUI now takes care of most of the details about fringe data acquisition and synchronization with the piezo scanner, and therefore a user's manual for NICMOS3 in this mode would amount to a user's manual of that part of the G3 GUI, which perhaps we should write soon. Conceptually, everything is the same, except that the frame times for the different readout modes are different because 4 pixels are sampled instead of 2 (see Nov 2000 note below).
From the hardware point of view, no FG is required in FLUOR mode since a digital-analog card in the G3 generates the piezo driving waveform for input to a PI amplifier.
To take NICMOS3 data in FLUOR mode, one must simply connect the Pentium's DIO-32F data transfer board to the analogous board in the G3, via a the special purpose 50 pin flat ribbon cable (which replaces a similar special purpose cable that connects to the Quadra - and has a BNC for receiving the FG TTL signal - in classical mode).
UPDATE: NOVEMBER 2000:
As mentioned above, the FLUOR Observing Software (OS) needs to know the Frame Rates (inverse of sampling time per data point) in order to apply the correct digital filtering in the QuickLook signal, which is the real time signal displayed and used by the fringe envelope tracking algorithm.
We have been used values deduced from timing in software the scan data acquisition time. Now I have actually measured the sampling time for each readout mode by measuring the time length of the HIGH state of the SAMPLE signal at the ADC card, and dividing by the number of data points in a scan selected when making this measurement (320 in this case). The results are shown below, and should be entered in the FLUOR OS. The measurement was made while sampling 4 pixels located in typical locations in our observing runs: column 1= row 1= 28, column 2 = row 2 = 36. Note that these measured values are pretty similar to the ones previously estimated.
|Samples/Frame (N Loops)||Reads/Sample (N Reads)||Sampling Time (ms)||Frame Rate (Hz)|