1. FSR was adjusted and measured with "the golden arches" technique again.
FSR = 264.8412 MHz +/- 1400Hz => Lcav = 1.13197 m. (nominal 1.132m)
2. Transverse mode spacings for the vertical and horizontal modes were measured.
TMS/FSR = 0.218144 (V) / 0.219748 (H)
This is almost perfect!
The 19th-order lower sideband hit the resonance. Next step is to glue some of the flat mirrors.