81
menu. Specify the number of averages, the number of waveforms desired to acquire,
the file format and destination. Once the time sequence starts, the software saves one
waveform named “Wfml”, which should be discarded later. Afterwards, the system
acquires a new waveform at every fall edge of the trigger signal.
Acquisition of each waveform in the T-ray 4000 system takes 10ms, thus the
maximum acquisition speed for the T-ray 4000 system is 100Hz (better use 50Hz
because of potential problems in software). For acquisition speed less than 10Hz,
the .picotd text file format or TDMS format can be used. Acquisition at higher rate
should use the picostream format, which can be converted to .picotd format under the
software File menu. Always ensure proper acquisition by setting the trigger period
10ms longer than the total time required for signal averaging. For example, 100 signal
averages would require the trigger period to be more than Is.
More questions about synchronization with the T-ray 4000 system should be di-
rected to Chris Megdanoff from Picometrix, LLC.
Caution: The frequency of the output trigger signal from the FPGA circuit always
equals to the input clock frequency divided by 256. See implemented Verilog programs
for more details.
B.8 System test procedure
All SLM experiments, including the SLM characterization experiments described in
the Section 5.5 or any future imaging experiments, require proper operation of the
SLM control system. Here briefly describes the procedure of testing the system for a
typical experiment.
1. Turn on the power supply, the signal generator and the oscilloscope.