NAOJ GW Elog Logbook 3.2
Displaying report 1-1 of 1.
YuefanGuo - 14:54, Wednesday 28 June 2017 (518)
Few works did with the electrical board
1. Video board
We changed the layout of the end bench, added one more mirror after the beam splitter to divide the beam into two, one is received by a screen and a camera was set to look at this screen, the other goes directly into the CCD. The mirror we used has the maximum reflection when it is putting in 45 degree, so we turned it a bit in order to have large enough power also for the transmission. The one received by the screen we took it as a reference for the alignment of the cavity and the CCD is to find a good mode matching. In this configuration we will need three images sending back from the end room at the same time(two on the end bench and one for the second target), the electrical board we are using now for the video only has two channels. So we took the same board from the west end, but it seems one channel of that board is broken, but it is enough for our current need. The fiber used to send the video signal now is '1-13,1-14,1-15,1-16', each board need two fibers. Also each monitor only can receive two channels, so we also took the monitor at the second target of west end to the central room.
2.Analog signal board
On the reflection path of the beam splitter on the end bench we put a PD before and use the receiver box to send this signal to central room for locking the cavity. But since the the aperture of the PD is limited, the spectrum we saw will also be effected by the alignment of the beam. So yesterday we changed the PD to PSD in order to have the information of the beam position. But in this way, we need to send back three analog signals together. We found two board for this and one of them have four channels. We tested the board with a sine wave sent from the end room board, and received it in the central room. The fiber they used for this board is too short to connect into the rack('1-11,1-12'), but the fiber system of TAMA is too complicated, so we just simply changed with longer spare fibers, now we are using '3-13,3-14' for this board.
From the board it seems we can change the gain and offset of each channel, but when we sent a 4V peak to peak signal, it pretty hard to see if it is changed or not, so maybe we can only changed in very small scale. Also it seems four channels all have different setting offset and gains, but we need further check about this.
We changed the layout of the end bench, added one more mirror after the beam splitter to divide the beam into two, one is received by a screen and a camera was set to look at this screen, the other goes directly into the CCD. The mirror we used has the maximum reflection when it is putting in 45 degree, so we turned it a bit in order to have large enough power also for the transmission. The one received by the screen we took it as a reference for the alignment of the cavity and the CCD is to find a good mode matching. In this configuration we will need three images sending back from the end room at the same time(two on the end bench and one for the second target), the electrical board we are using now for the video only has two channels. So we took the same board from the west end, but it seems one channel of that board is broken, but it is enough for our current need. The fiber used to send the video signal now is '1-13,1-14,1-15,1-16', each board need two fibers. Also each monitor only can receive two channels, so we also took the monitor at the second target of west end to the central room.
2.Analog signal board
On the reflection path of the beam splitter on the end bench we put a PD before and use the receiver box to send this signal to central room for locking the cavity. But since the the aperture of the PD is limited, the spectrum we saw will also be effected by the alignment of the beam. So yesterday we changed the PD to PSD in order to have the information of the beam position. But in this way, we need to send back three analog signals together. We found two board for this and one of them have four channels. We tested the board with a sine wave sent from the end room board, and received it in the central room. The fiber they used for this board is too short to connect into the rack('1-11,1-12'), but the fiber system of TAMA is too complicated, so we just simply changed with longer spare fibers, now we are using '3-13,3-14' for this board.
From the board it seems we can change the gain and offset of each channel, but when we sent a 4V peak to peak signal, it pretty hard to see if it is changed or not, so maybe we can only changed in very small scale. Also it seems four channels all have different setting offset and gains, but we need further check about this.