US PATENT SUBCLASS 359 / 742
.~.~ Echelon (e.g., Fresnel lens, etc.)

Current as of: June, 1999
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359 /   HD   OPTICS: SYSTEMS (INCLUDING COMMUNICATION) AND ELEMENTS

642  DF  LENS {32}
741  DF  .~ With multipart element {1}
742.~.~ Echelon (e.g., Fresnel lens, etc.) {1}
743  DF  .~.~.~> Having curvilinear lens

DEFINITION

Classification: 359/742

Echelon (e.g., Fresnel lens, etc.):

(under subclass 741) Subject matter wherein at least one of the refracting surfaces of the lens is discontinuous, being formed of a plurality of stepped refracting surfaces connecting at their adjacent edges by other surfaces which extend substantially parallel to the intended direction of light travel through the lens, the surfaces being so shaped

and arranged that they form in conjunction with the opposed refracting surface of the lens, a plurality of lenses all of which have a common focus.