Optical system for inverted microscopes

Claim 1

An optical system for extending the distance between a conventional infinity-corrective microscope objective and a telescope lens, which comprise a pair of bi-convex triplets, a mirror, and a pentaprism having the parameters set forth below where lens radii (R 1 -R 8 ), a minus sign (-) indicates the center curvature on the back focal plane side of the surface vertex, lens thicknesses (T 1 -T 6 ), axial spacings along the optical axis of the system (S 1 -S 7 ), refractive indicies (ND 1 -ND 6 ), and Abbe numbers (ν 1 -ν 6 ) are determined by the following relationship, all radii, thicknesses and spacings being in millimeters. ______________________________________ Thick- Refractive Abbe Radius ness Spacing Index Number Lens R T S ND ν ______________________________________ S.sub.1 =118.9 R.sub.1 =85.285 T.sub.1 =6.0 ND.sub.1 =1.504 ν.sub.1 =66.9 R.sub.2 =-52.24 I T.sub.2 =3.2 ND.sub.2 =1.613 ν.sub.2 =44.3 R.sub.3 =31.84 T.sub.3 =6.0 ND.sub.3 =1.589 ν.sub.3 =48.7 R.sub.4 =-113.24 S.sub.2 =17.2 S.sub.3 =101.0 S.sub.4 =87.9* S.sub.5 =17.1** S.sub.6 =26.3* R.sub.5 =113.24 T.sub.4 =6.0 ND.sub.4 =1.589 ν.sub.3 =48.7 R.sub.6 =-31.84 II T.sub.5 =3.2 ND.sub.5 =1.613 ν.sub.5 =44.3 R.sub.7 =52.24 T.sub.6 =6.0 ND.sub.6 =1.504 ν .sub.6 =66.9 R.sub.8 =-85.285 S.sub.7 =213.6 ______________________________________ ##STR3## - ##STR4##