| Huygenian eyepiece | <microscopy> An under corrected (blue rim at periphery of field) ocular designed by Huygens for the telescope and later adopted for achromatic objectives. This ocular consists of two plano-convex lenses separated by a diaphragm, hence it is of the negative type with the focal plane inside the system. Both plane surfaces face the eye, as distinguished from the Ramsden eyepiece. (05 Aug 1998) |
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