The Renishaw RGH24 is what we use in our Trilogy positioners for the optical encoder option.
The W version is .2um, has a 6MHz clock frequency option and a maximum speed of 700mm/sec. Since the clock frequency is less than the maximum input frequency into the Gemini drive, which is 8MHz (post quad), this is a compatible readhead.
The Y version is .1um, has an option for 8MHz clock frequency. This would also be compatible with the Gemini drive. However, it has a maximum speed limit of 500mm/sec. Depending upon the application requirements, this may work.
If you are needing higher speeds but with .1um resolution, it would be a good idea to change the amplifier from the Gemini to the newer Aries which has a higher 5MHz pre-quad (which would be 20MHz post-quad) maximum input frequency. Then use the RGH24Y with the 30 option (12MHz frequency).
The Aries is an AC powered servo drive, much like the Gemini. It has more advanced electronics (higher encoder frequency and higher servo update rates) but many of the same features of the base Gemini drive. The ViX is a DC powered servo drive and that would work with this read-head as well because it has a 12MHz post-quad max encoder frequency.
Full specifications of the RGH24 optical encoder are available from the Renishaw website: