Achromatic condenser for microscope

Claim 1

A lens having a focal length f and comprising a plurality of optical elements described by successive subnumerated radii R taken as positive when centered on one side of said lens and negative when centered on the other side and ratioed to f, by successive subnumerated thicknesses t and spatial separations S both ratioed to f, and by successive subnumerated glass characteristics, refractive indices nD and dispersions Nu , said plurality of optical elements comprising in increasing consecutive numerical order: a substantially plano parallel plate I of radii R1 and R2 and thickness t1; a plano-hemispheroidal lens II of radii R2 and -R3 and thickness t2 in surface contact with said plate I; a positive meniscus lens III of radii -R4 and -R5 very narrowly spaced by a space S1, from said lens II; a biconvex lens IV of radii R6 and -R7 and thickness t4 airspaced from said lens III by a space S2; a substantially plano parallel plate V having radii R8 and R9 and thickness t5 airspaced from said lens IV by a space S3; a biconvex lens VI of radii R10 and -R11 and thickness t6 airspaced from said plate V by a space S4; a negative meniscus lens VII of radii -R11 and -R12 and thickness t7 in surface contact with said lens VI; a biconvex lens VIII of radii R13 and -R14 and thickness t8 Airspaced from said lens VII by a space S5; a negative meniscus lens IX of radii -R14 and -R15 and thickness t9 in surface contact with said lens VIII; a biconcave lens X of radii -R16 and R17 and thickness t10 airspaced from said lens IX by a space S6; and a lens XI widely airspaced by a space S7 from said lens X said lens XI being defined by a substantially plano radius R18 facing said lens X, a radius -R19, and a thickness t11: wherein: 10f<R1<-10f10f<R2<-10f0.036f<-R3<0.039f0.160f< -R4<0.162f0.096f<R5<0.098f0.262f<R6<0.264f0.202f<-R7<0.204f10f<R8<-10f 10f<R9<10f0.345f<R10<0.381f0.134f< -R11<0.144f0.431f<R12<0.497f0.169f<R13<0.179f0.143f< -R14<0.162f1.211f<R15<2.398f0.257f<-R16<0.261f0.815f<R17<0.896f10f<R18< -10f0.279f<R19<0.281f0.002f<t1<0.005f0.050f<t2<0.053f0.033f<t3<0.037f0.060f< t4<0.063f0.009f<t5<0.016f0.051f<t6<0.061f0.019f<t7<0.031f0.051f<t 8<0.063f0.011f<t9<0.015f0.013f<t10<0.018f0.032f<t11<0.038f0<S1<0. 001f0.0002f<S2<0.003f0.043f<S3<0.050f0.010f<S4<0.012f0.001f<S5<0. 003f0.009f<S6<0.011f0.330f< S7 (focusable)<0.370f 1.718<nD1<1.7221.515<nD2<1.5191.515<nD3<1.5191.521<nD4<1.5251.520 <nD5<1.5241.515<nD6<1.5191.749<nD7<1.7531.515<nD8<1.5191.718<nD9< 1.7221.718<nD10<1.7221.539<nD11<1.54328.3< Nu 1<30.363.5< Nu 2<65.563.5< Nu 3<65.557.6< Nu 4<59.657.6< Nu 5<59.663.5< Nu 6<65.526.8< Nu 7<28.863.5< Nu 8<65.528.3< Nu 9<30.328.3< Nu 10<30.358.9< Nu 11<60,9