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AIS is an acronym for Alignment Initialization System.
 
AIS is an acronym for Alignment Initialization System.<<BR>>
{{attachment:AIS_MEDM.png}} <<BR>>
The current AIS is in a very primitive state, but does a job well.

There is a sin-cos signal generator at the top left. This signal goes out from the DAC to be injected to a pitch or yaw actuator of an optics. The signal is also used as a LO for demodulators. Signals from a QPD are filtered for line removal and AC coupling. The demodulated signal is filtered by a LPF and a comb filter of 10Hz harmonics.

The alignment script ({{{DitherAlignment.py}}} obtains the error signal by reading an EPICS channel, such as K1:CTR-AIS_TRX_DEMOD_OUT.

=== Usage of the alignment script ===
First, you have to make sure that the EPICS-PicoMotor system is properly running.

Auto Alignment Script

This page explains the automatic alignment script. It resides in /cvs/cds/kami/scripts/AutoAlignment/

Working Principle

The dither alignment technique uses a sinusoidal signal to move a mirror in pitch or yaw. By demodulating the transmitted power signal at the same frequency as the excitation signal, we can obtain an error signal of misalignment.

Implementation

There are three parties involved in the dither alignment. The first one is the realtime code, which does the excitation and demodulation. Then the demodulated signal is read by a python script called DitherAlignment.py. This script feedback the error signal to corresponding Picomotors by writing appropriate values to EPICS PVs which are monitored by pmepics.py. The daemon script pmepics.py is responsible to drive Picomotors according to the values of the EPICS PVs reserved for Picomotors.

AIS realtime code

AIS is an acronym for Alignment Initialization System.
AIS_MEDM.png
The current AIS is in a very primitive state, but does a job well.

There is a sin-cos signal generator at the top left. This signal goes out from the DAC to be injected to a pitch or yaw actuator of an optics. The signal is also used as a LO for demodulators. Signals from a QPD are filtered for line removal and AC coupling. The demodulated signal is filtered by a LPF and a comb filter of 10Hz harmonics.

The alignment script (DitherAlignment.py obtains the error signal by reading an EPICS channel, such as K1:CTR-AIS_TRX_DEMOD_OUT.

Usage of the alignment script

First, you have to make sure that the EPICS-PicoMotor system is properly running.

CLIO/AutoAlignmentScripts (last edited 2010-04-16 15:06:39 by YoichiAso)