ECR Title: ECR: Fiber Polarization Correction	DCC No: E12xxxxx-vx
Date: 10/2/2012
Requester: Daniel Sigg	Impacted Subsystem(s): ISC
Description of Proposed Change(s): Add a motorized polarization controller at the launch point of the fibers (MSR). Add a polarizer and a sampler to each fiber exit port in the end stations.
Reason for Change(s): We observed during OAT that the polarization of the fiber beam on ISCBT10R changed slowly over time. This required us to manually adjust a halfwave plate. Worse, we had no diagnostics to indicate the problem. Adding a polarizer and measuring both the passed-through and the rejected beam will remedy this problem. Adding a motorized polarization controller further allows us to correct for polarization drift automatically.
Estimated Cost: Fiber Control MPC1-2-2-2-FC-UPC-R (3 dual channel units): 34,500 Optics (polarizer, sampler, mounts): $4,800 Total: $39,300
Schedule Impact Estimate: None.
Nature of Change (check all that apply): Safety Correct Hardware Correct Documentation	Improve Hardware Improve/clarify Documentation Change Interface Change Requirement
Importance: Desirable for ease of use, maintenance, safety Desirable for improved performance, reliability Essential for performance, reliability Essential for function Essential for safety	Urgency: no urgency desirable by date/event: _Feb 2013____ Essential by date/event: ____________ Immediately (ASAP)
Impacted Hardware (select all that apply): Repair/modify. List part & SNs: ______________________ Scrap & Replace. List part & SNs:_____________________ Installed units? List IFO, part & SNs: _________________ Future units to be built	Impacted Documentation (list all dwgs, design reports, test reports, specifications, etc.): D1100607, MSR drawing
Disposition (to be completed by Systems Engineering): TRB CCB Approved Additional information required. Define: [Requester re-submits with new information with the same DCC E-number for the ECR but the next version number.] Concurrence by Project Management: (Acknowledged Electronically in DCC) Project Systems Engineer: Dennis Coyne Project Systems Scientist: Peter Fritschel