[Ian, Daniel]

We met to discuss the window design for the LFC with a cavity length of 4.49 meters. We looked at windows and single and multi port conflats and decided that the best option was to use the four port CF0600X4 (diagram of the conflat here). This would allow us to access inputs and outputs for each mirror if needed. I don't think we have any plans to use 775 nm to control the cavity but having the extra ports would allow for that and allow for different orientations for cavity. for example if we decide we want to have it enter and exit at a different port in the future. 

With the preferred conflat and window I did the calculation for where to put the mirrors. In window geometry notebook I calculate how far apart the mirrors need to be and the angle between the incoming and reflected beam. 

If we want all of the cavities inputs and outputs to be available then the angle of the incoming and reflected beam should be 3.7 degrees. This uses the middle 25% of the window so there shouldn't be any distortion. This gives a mirror separation of 2.2 inches from center to center. This is rather close but should be useable. These calculations also offer some wiggle room for moving the mirrors slightly apart. With this geometry the beam angle of 3.7 degrees means that the beams will be separated by about 1.2 inches one foot behind the cavity mirror (M1). This means the beams can be separated without too much trouble. I will update the layout for the LFC area also.

The windows for the chamber should be 2.75 inch windows with an AR coating for 1550. The VPZL-275LDIO2 which is the right size and optimized with the correct AR coating. If we wanted to use a 775 nm control we would use  the VPZL-275LDIO3 which is optimized for 808 nm.

We also came up with the mounts: we should get 1 Polaris-K1S3P which has piezoelectric control and 3 Polaris-K1S5 for the other mirrors.