Optometer eyepiece

A four component optometer eyepiece being substantially free of chromatic aberration comprising a biconcave negative singlet I, a plano-convex positive singlet II, a biconvex positive singlet III and a biconvex positive doublet IV all aligned in sequence along an optical axis and having the values set forth below with axial thicknesses of the successive lens components being designated T.sub.1 to T.sub.5, successive axial spaces from the first component to an observer's eye being designated S.sub.1 to S.sub.4, successive lens radii being designated R.sub.1 to R.sub.9 where the minus sign (-) indicates surfaces whose center of curvature lies on an observer's side of their vertices, refractive indices and Abbe numbers are absolute values designated ND.sub.1 to ND.sub.5 and .nu..sub.1 to .nu..sub.5, respectively,

• ______________________________________ Thick- Index of ness Refraction Abbe Lens Radius(R) (T) Spacing(S) (ND) No. ( ) ______________________________________ R.sub.1 = 0.90598x T.sub.1 = 1.58<
• I R.sub.2 = 0.034188x ND.sub.1 <1.60 .nu..sub.1 =61 0.90598x S.sub.1 = R.sub.3 = 0.28222x 100x T.sub.2 = 1.58<
• II R.sub.4 = 0.051282x ND.sub.2 <1.60 .nu..sub.2 =61 1.6036x S.sub.2 = R.sub.5 = 0.0008547x 1.5231x T.sub.3 = 1.58<
• III R.sub.6 = 0.068376x ND.sub.3 <1.60 .nu..sub.3 =61 0.89786x S.sub.3 = R.sub.7 = 0.17239x -1.8352x T.sub.4 = 1.58<
• R.sub.8 = 0.08547x ND.sub.4 <1.60 .nu..sub.4 =61 IV 0.42966x T.sub.5 = 1.77<
• R.sub.9 = 0.059829x ND.sub.5 <1.79 .nu..sub.5 =26 1.1479x S.sub.4 = 0.9982x and x is 115 to 119mm. ______________________________________