See
http://translate.google.com.au/trans...%3Den%26sa%3DG
http://www.activenet.ru/storage/astr...hara/FPL51.pdf
http://www.activenet.ru/storage/astr...hara/FPL53.pdf
If you can find the Abbe No and n , you can compare.
Hoya say "
Extremely Low Dispersion Glass: FCD1
Low change in refractive index with different wavelength of light minimizes focusing error caused by the varying wavelength output by laser diodes"
According to
http://www.cdgmglass.com/glassreference.asp FCD1 is equivalent to FPL51.
Just have to use the right key words and be prepared to drill.
Guess Meade's claim of "highest quality" is hype unless you are looking at Meade's APOs. Will be a very nice bit of kit nonetheless.