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--- groups:mg:experiment:laser:tisa [2015/08/14 10:29] – ssauer
+++ groups:mg:experiment:laser:tisa [2018/10/23 16:40] (current) – [Locking the TiSa] njha
@@ Line 9: / Line 9: @@
 ==== Locking the TiSa ====
-TODO
+The TiSa is locked to a transfer cavity. The PID for this lock works in series mode where the output of the "current" part of the PID is used as input for the "piezo" part of the PID. The PID scheme has been modified as well. Since the fast output of PID goes to the high voltage amplifier (which only takes in 0-10 volts input) which then drives the fast piezo in TiSa, we have added an offset 5 Volts on this output. The high voltage amplifier is based on the Apex PA98 op-amp. This has roughly an amplification factor of 15 and can go from -15 V to 250 V. There is a low pass filter of 50 kHz placed within the amplifier to limit the bandwidth. Also the maximum current of the amplifier is also limited. The TiSa fast piezo can be operated in +- 300 V range and the capacitance of piezo is 3 nF. The first resonance of the piezo is at around {{ :groups:mg:experiment:laser:piezo_response_directly_measured_by_network_analyzer.pdf |77 kHz}}. Therefore the PID bandwidth is limited to around 33 kHz.
+The whole PID modified scheme is attached here: {{ :groups:mg:experiment:laser:tisa_lockpid.pdf |}}
 ====== Aligning the TiSa ======
 Alignment for the TiSa has to be done from time to time.