Describe LCGT/subgroup/ifo/ISC/TaskList/SpatialMode/SpatialModeDesign here.

== Preliminary (base) desisn of folded stable cavities ==
The task is to determine the locations and the ROCs of the folding mirrors given the following constraints.

=== Boundary Conditions ===
The boundary conditions for the design of the folded RCs are the following. {{attachment:BoundaryCondition.png||width="700"}}

 * The TEM00 mode in the RCs should match the arm cavity modes.
 * Out of 73m of the RC length, 25m should be allocated between the BS and the ITMs for radiation shield.
 * The Gouy phase shift in the RC (one-way) must be about 20deg.
 * The beam spot sizes on the optics should not be too small (what is the tolerance ?).
 * The incident angle of the beam to the folding mirrors should be as small as possible, to avoid astigmatism (1deg max).
 * There is a minimum distance between two optics (e.g., the PRM and PR2) coming from the size of the SAS.

== Design of folded stable cavities ==
 * [[attachment:folded_report_v7.pdf]]
 * [[attachment:ROC_ERROR_v2.pdf]] (revised on 2010-07-14)
 * [[attachment:LCGT_thermal_lens_v2.pdf]]
 * [[attachment:folded_negative_v2.pdf]]
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 * [[attachment:back_scattered_power.pdf]]
 * [[attachment:telescope_optimize.pdf]]
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 * [[attachment:ISC_SMD_100804_v2.pdf]]

== Design of unfolded stable cavities ==
 . [[attachment:100429.pdf]]

== Current design of marginally stable cavities ==
== Some limitations in the view of vacuum and seismic attenuation group ==
 * maximum beam shift
 * minimum tank separation

== Higher order mode check ==
Higher order modes of the arm cavities should not overlap with sidebands and their harmonics.

This was checked [[LCGT/subgroup/ifo/ISC/TaskList/SpatialMode/SpatialModeDesign/HOMCheck|here]].

== Old (current) layout of vacuum tanks ==
 * Layout
 * Limitations