Describe OMC mode scanning here.
First, make sure you've completed the OMC Alignment. Recently.
There's a DTT template in /cvs/cds/caltech/users/rward/OMC/MODAL_CONTENT/OMC_MODE_SCAN_template.xml. Open this template.
Make sure the OMC length servo is off. Turn off the integrator. Set the LSC_OUTPUT offset to 5000.
Make sure the OMC alignment servos are off. Leave the integrators on.
Run the DTT template you opened. When it's done, save the results using "Save As". DO NOT save the results in this template file name, as the data is huge and so it takes years to open/write.