Wide angle eyepiece

Claim 1

An eyepiece comprising a doublet, a singlet, a singlet, and a doublet, wherein each doublet includes a biconcave element cemented to a biconvex element and has a negative power, and each singlet is a biconvex lens with its stronger curvature facing the other singlet, and wherein the biconcave lens elements have a refractive index of 1.717 and an Abbe Number of 29.5 and the biconvex lens elements have a refractive index of 1.620 and an Abbe Number of 60.3, and wherein, for a 40 mm. focal length eyepiece, the lens data conforms substantially to the following table wherein lens radii, diameters, and axial thicknesses are given in millimeters: ______________________________________ Lens Radii Axial Thickness Lens Diameter ______________________________________ r1 = -98.30 d1 = 3.55 50 r2 = +68.76 d2 = 10.22 50 r3 = -123.86 r4 = +234.80 d3 = 10.22 56 L3 r5 = -82.86 r6 = +76.48 d4 = 15.32 60 L4 r7 = -111.24 r8 = +60.13 d5 = 21.21 60 L5, L6 r9 = -54.27 d6 = 4.42 r10 = +66.20 ______________________________________ and the separations between the doublets and the adjacent singlets, and between the singlets are 0.30 mm. air spaces.