The Collaborative International Dictionary of English v.0.48:

Huyghenian \Huy*ghe"ni*an\, a.
   Pertaining to, or invented by, Christian Huyghens, a Dutch
   astronomer of the seventeenth century; as, the Huyghenian
   telescope.
   [1913 Webster]

   Huyghenian eyepieceSee under Eyepiece.
      [1913 Webster]