An interesting paper
describes a new design for an earthshine telescope. They describe the essential instrument.
It seems to me that:
1) they only have 2 lenses (although both are doublets - we have one doublet and two singlets)
2) Their masks (like our SKE) sits outside the telescope. At least thatmakes it easier to fix when it breaks.
3) Their telescope is a Cassegrain system - so lots of optics there...
Hmm. We should try to understand this design in case we want to try fresh approaches. Perhaps it is an option for a FW-less CMOS-based system?
It seems their 'instrument' sits on a conventional telescope - so many many optical surfaces in total...