Photo eyepiece for microscopes

Claim 2

A photo eyepiece for microscopes comprising a front lens group comprising a first lens and rear lens group comprising a second, third and fourth lenses, said first lens being a positive lens, said second lens being a biconvex lens, said third lens being a negative lens, said fourth lens being a biconvex lens, said photo eyepiece for microscopes satisfying the following conditions: 2.0 < f1/f234 < 2.77 (1) 0.73 < d2/f < 0.75 (2) 0.2 < |r6 |/f < 0.26 (3) 1.65 < (n2 + n4)/2 < 1.68 (4) 0.06 < n3 - n4 < 0.084 wherein reference symbol f represents the focal length of the lens system as a whole, reference symbol f1 represents the focal length of the first lens, i.e., of the front lens group, reference symbol f234 represent the focal length of the rear lens group, reference symbol r6 represents the radius of curvature of the surface on the image side of the third lens, reference symbol d2 represents the airspace between the front and rear lens groups, and reference symbols n2, n3 and n4 respectively represent refractive indices of the second, third and fourth lenses.

Claim 3

A photo eyepiece for microscopes according to claim 1 further satisfying the following condition: 0.09 < d7/f < 0.16 wherein reference symbol d7 represents the thickness of the fourth lens.

Claim 4

A photo eyepiece for microscopes according to claim 1, in which said photo eyepiece for microscopes has the following numerical data: ______________________________________ f = 1.0 r1 = 0.3808 d1 = 0.0876 n1 = 1.62041 ν1 = 60.27 r2 = 0.5603 d2 = 0.7360 r3 = 0.6860 d3 = 0.0678 n2 = 1.640 ν2 = 60.09 r4 = -0.6695 d4 = 1.1550 r5 = -3.2301 d5 = 0.0290 n3 = 1.76182 ν3 = 26.55 r6 = 0.2033 d6 = 0.0968 r7 = 0.3764 d7 = 0.0968 n4 = 1.6779 ν4 = 55.33 r8 = -0.4025 f1 = 1.6139 f234 = 0.5832 ______________________________________ wherein reference symbols r1 through r8 respectively represent radii of curvature of respective lens surfaces, reference symbols d1 through d7 respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n1 through n4 respectively represent refractive indices of respective lenses, reference symbols ν1 through ν4 respectively represent Abbe's numbers of respective lenses, reference symbol f represents the focal length of the lens system as a whole, reference symbol f1 represents the focal length of the front lens group, and reference symbol f234 represents the focal length of the rear lens group.

Claim 5

A photo eyepiece for microscopes according to claim 1, in which said photo eyepiece for microscopes has the following numerical data: ______________________________________ f = 1.0 r1 = 1.7029 d1 = 0.1210 n1 = 1.7620 ν1 = 40.2 r2 = -2.2936 d2 = 0.7464 r3 = 1.1145 d3 = 0.0814 n2 = 1.6516 ν2 = 58.67 r4 = 2.0890 d4 = 0.0922 r5 = 1.4063 d5 = 0.0352 n3 = 1.76182 ν3 = 26.55 r6 = 0.2598 d6 = 0.0896 r7 = 0.3621 d7 = 0.1496 n4 = 1.6968 ν4 = 55.52 r8 = -0.7023 f1 = 1.2995 f234 = 0.6262 ______________________________________ wherein reference symbols r1 through r8 respectively represent radii of curvature of respective lens surfaces, reference symbols d1 through d7 respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n1 through n4 respectively represent refractive indices of respective lenses, reference symbols ν1 through ν4 respectively represent Abbe's numbers of respective lenses, reference symbol f represents the focal length of the lens system as a whole, reference symbol f1 represents the focal length of the front lens group, and reference symbol f234 represents the focal length of the rear lens group.