26 opposite the reservoir 24 is a fill tube 28 and shutoff valve 30 through which liquid plastic can be introduced to fill the reservoir 24 a two way valve 32 in the pumping tube 22 permits the pumping tube 22 and chamber 20 to be either evacuated using a vacuum means 36 or vented to the atmosphere through vent tube 34 fig3 and 4 are schematic illustrations of cross sectional and planar views respectively or a fresnel lens 40 fabricated by the method of the invention the lens comprises a transparent substrate 10 having opposed surfaces 12 and 14 bonded to the surface 14 of said substrate is the plastic layer 42 this plastic layer 42 has refracting facets 44 which correspond to the segments of the master fresnel lens used to form the mold a particular set of facet interconnect channels 50 used in the lens fabrication are shown in fig4 using the fabrication technique of the invention the grooves 46 between the individual facets 44 reach down essentially to the glass surface 14 the thickness of the sublayer 48 varies from zero to about 0 0075 cm which is less than it is possible to obtain using other conventional molding or casting methods the overall thickness of plastic layer 42 can vary from about 0 025 to about 0 10 cm it is desirable that the thickness of sublayer 48 be as thin as possible since bulk sheer stresses produced by thermal expansion and contraction during manufacture and use can cause loss of bonding of the plastic layer 42 to the substrate 10 the invention is a multi step process for the fabrication of the novel fresnel lens prior to the fabrication of the fresnel lens a plastic mold which is flexible after curing or hardening is.