This is an update on the situation as far as PZT installation is concerned. I measured the required cable (PZT driver board to PZT) lengths for the X and Y ends as well as the PSL table once again, with the help of a 3m long BNC cable, just to make sure we had the lengths right. The quoted cable lengths include a meter tolerance. The PZTs themselves have cable lengths of 1.5m, though I have assumed that this will be used on the tables themselves. The inventory status is as follows.
- Stuff ordered:
- RG316 LEMO 00 (female) to SMB (female) cables, 10 meters - 6pcs (for the Y-end)
- RG316 LEMO 00 (female) to SMB (female) cables, 11 meters - 6pcs (for the X-end)
- RG316 LEMO 00 (female) to SMB (female) cables, 15 meters - 8pcs (6 for the PSL, and two spares)
- RG316 SMA (male) to open cables, 3 meters - 3pcs (1 each for the X end, Y end and PSL table, for connecting the driver boards to the 100V DC power supply)
- 10 pin IDC connectors for connecting the DAC interface to the PZT driver boards
- Stuff we have:
- 40 pin IDC connectors which connect to the DAC interface
- PZT driver boards
- PZT mounts
- Twisted ribbon wire, which will be used to make the custom ribbon to connect the 10 pin IDC to the 40 pin IDC connector
I also did a preliminary check on the driver boards, mainly to check for continuity. Some minor modifications have been made to this board from the schematic shown here (using jumper wires soldered on the top-side of the PCB). I will have to do a more comprehensive check to make sure the board as such is functioning as we expect it to. The plan for this is to first check the board without the high-voltage power supply (using an expansion card to hook it up to a eurocrate). Once it has been verified that the board is getting powered, I will connect the high-voltage supply and a test PZT to the board to do both a check of the board as well as a preliminary calibration of the PZTs.
To this end, I need something to track the spot position as I apply varying voltage to the PZT. QPDs are an option, the alternative being some PSDs I found. The problem with the latter is that the interfaces to the PSD (there are 3) all seem to be damaged (according to the labels on two of them). I tried connecting a PSD to the third interface (OT301 Precision Position Sensing Amplifier), and hooked it up to an oscilloscope. I then shone a laser pointer on the psd, and moved it around a little to see if the signals on the oscilloscope made sense. They didn't on this first try, though this may be because the sensing amplifier is not calibrated. I will try this again. If I can get one of the PSDs to work, mount it on a test optical table and calibrate it. The plan is then to use this PSD to track the position of the reflected beam off a mirror mounted on a PZT (temporarily, using double sided tape) that is driven by feeding small-amplitude signals to the driver board via a function generator.
Misc
The LEMO connector on the PZTs have the part number LEMO.FFS.00, while the male SMB connectors on the board have the part number PE4177 (Pasternack)
Plan of Action:
- The first task will be to verify that the board is working by the methods outlined above.
- Once the board has been verified, the next task will be to calibrate a PZT using it. I have to first identify a suitable way of tracking the beam position (QPD or PSD?)
- I have identified a position in the eurocrate at 1Y4 to install the board, and I have made sure that for this slot, the rear of the eurocrate is not hooked up to the cross-connects. I now need to figure out the exact pin configuration at the DAC interface: the bank is marked 'DAC Channels 9-16' (image attached) but there are 40 pins in the connector, so I need to map these pins to DAC channels, so that when making the custom ribbon, I get the pin-to-pin map right.
The wiring scheme has been modified a little, I am uploading an updated one here. In the earlier version, I had mistaken the monitor channels as points from which to log data, while they are really just for debugging. I have also revised the coaxial cable type used (RG316 as opposed to RG174) and the SMB connector (female rather than male).
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