Microscope objective for accommodating different cover-glass thicknesses

Claim 2

In a microscope for observing objects covered by cover-glasses of differing thicknesses, an objective having a linear magnification of between 32× and 60×, an aperture of at least 0.5, and an optical axis along which are aligned, in the order of light transmission, a stationary first lens (L1), a movable second lens (L2/L3), and a stationary third lens (L4), said microscope objective comprising: a. a movable fourth lens (L5) arranged beyond said third lens in said order of light transmission; and b. an adjusting device, selectively positionable in accordance with the thickness of the cover-glass covering an object being observed, for moving said second and fourth lenses to adjust the objective to compensate for said cover-glass thickness, the movement of said fourth lens being in a direction opposite to movement of said second lens.

Claim 3

The microscope objective of claim 1 wherein the movements of said second and fourth lenses are linear.

Claim 4

The microscope objective of claim 1 wherein the stroke of movement of said fourth lens is larger than the stroke of movement of said second lens.

Claim 5

The microscope objective of claim 3 wherein said strokes of movement differ by at least a factor of three.

Claim 6

The microscope objective of claim 1 wherein said third lens is held in a centering mount.

Claim 7

The microscope objective of claim 1 wherein all of said lenses are mounted within a carrier (11) which is itself movable along said optical axis for focusing the objective, and wherein the selective positioning of said adjusting device also moves said carrier for resetting the focus of said microscope objective.

Claim 8

The microscope objective of claim 6 wherein said adjusting device includes a single actuating ring arranged for causing said opposing movement of said second and fourth lenses and for moving said carrier.

Claim 9

The microscope objective of claim 7 wherein said adjusting device includes a thread on an intermediate ring coupled with said actuating ring.

Claim 10

The microscope objective of claim 8 wherein said adjusting device includes two cams connected respectively to mounts for said second and fourth lenses and engaged respectively in grooves of constant but different pitch in said intermediate ring.

Claim 11

The microscope objective of claim 1 wherein movement of said fourth lens to change an air separation distance (d10) from said stationary third lens changes a field correction of said microscope objective for astigmatism.

Claim 12

The microscope objective of claim 1 wherein both of said first and third lenses are positive single lenses.

Claim 13

The microscope objective of claim 1 wherein said movable second lens has a positive refractive power.

Claim 14

The microscope objective of claim 1 wherein said movable fourth lens is a cemented component of negative refractive power.

Claim 15

The microscope objective of claim 1 in a planachromatic form containing eight lenses in four groups, arranged so that: said first lens (L1) is in the form of a concave-convex converging lens; said second lens includes a concave-convex single lens (L2) at a distance (d2) from said first lens (L1) and a cemented component (L3) consisting of three lenses, the middle lens of which is a bi-convex converging lens opposed by a convex-concave dispersing lens and a concave-convex dispersing lens; said third lens (L4) is a bi-convex single lens at a distance (d8) from said cemented component (L3); said fourth lens (L5) is a cemented component consisting of a bi-convex converging lens and a bi-concave dispersing lens at a distance (d10) from said third lens (L4); and said distances (d2, d8, and d10) are variable for said adjustment to said different cover-glass thicknesses.

Claim 16

The microscope objective of claim 14 wherein said lenses are structured according to the following table for lens radii r, lens thicknesses and distances d, indexes of refraction nd, and Abbe numbers γd of the values of said lenses, to produce the indicated linear magnification and numerical aperture and accommodate cover-glass thicknesses from zero to 2 millimeters, as follows: TABLE I __________________________________________________________________________ Index of Abbe Radius Thickness Distance Refrac- Number Lens r/mm d/mm d/mm tion nd γ d __________________________________________________________________________ r1 = -3.566 L1 d1 = 3.24 1.5205 69.7 r2 = -3.839 d2 = 1.43 to 0.48 r3 = -659.4 L2 d3 = 2.50 1.5891 61.3 r4 = -10.96 d4 = 0.62 r5 = 48.448 d5 = 1.0 1.6134 44.3 r6 = 7.515 L3 d6 = 4.7 1.4866 84.5 r7 = -8.485 d7 = 1.0 1.8807 41.0 r8 = -24.36 d8 = 0.20 to 1.15 r9 = 17.013 L4 d9 = 3.0 1.5285 77.0 r10 = -25.925 d10 = 15.75 to 19.06 r11 = 8.593 d11 = 4.0 1.4585 67.7 L5 r12 = -29.03 d12 = 1.5 1.6967 56.4 r13 = 5.975 __________________________________________________________________________ Cover-glass: 0 to 2 mm Working distance: W = 3.3 mm to 2.2 mm Linear magnification: β = 40 x Numerical aperture: A = 0.6.

Claim 17

The microscope objective of claim 14 wherein said lenses are structured according to the following table for lens radii r, lens thicknesses and distances d, indexes of refraction nd, and Abbe numbers γd of the values of said lenses, to produce the indicated linear magnification and numerical aperture and accommodate cover-glass thicknesses from zero to 2 millimeters, as follows: TABLE II __________________________________________________________________________ Index of Abbe Radius Thickness Distance Refrac- Number Lens r/mm d/mm d/mm tion nd γ d __________________________________________________________________________ r1 = -2.751 L1 d1 = 2.05 1.5205 69.7 r2 = -3.110 d2 = 1.44 to 0.21 r3 = -132.1 L2 d3 = 2.15 1.4866 84.5 r4 = -7.032 d4 = 3.38 r5 = 34.383 d5 = 2.0 1.5986 46.9 r6 = 9.040 L3 d6 = 5.0 1.4866 84.5 r7 = -7.766 d7 = 1.0 1.8807 41.0 r8 = -17.974 d8 = 3.73 to 4.96 r9 = 15.281 L4 d9 = 3.0 1.4866 84.5 r10 = -163.8 d10 = 10.48 to 16.07 r11 = 5.862 d11 = 3.9 1.4875 70.4 L5 r12 = -21.964 d12 = 1.0 1.6228 56.9 r13 = 4.278 __________________________________________________________________________ Cover-glass: 0 to 2 mm Working distance: W = 2.4 mm to 1.55 mm Linear magnification: β = 32 x Numerical aperture: A = 0.55.

Claim 18

The microscope objective of claim 14 wherein said lenses are structured according to the following table for lens radii r, lens thicknesses and distances d, indexes of refraction nd, and Abbe numbers γd of the values of said lenses, to produce the indicated linear magnification and numerical aperture and accommodate cover-glass thicknesses from zero to 2 millimeters, as follows: TABLE III __________________________________________________________________________ Index of Abbe Radius Thickness Distance Refrac- Number Lens r/mm d/mm d/mm tion nd γ d __________________________________________________________________________ r1 = -3.563 L1 d1 = 2.21 1.5205 69.7 r2 = -3.091 d2 = 1.40 to 0.11 r3 = -354.6 L2 d3 = 2.22 1.4866 84.5 r4 = -8.262 d4 = 0.9 r5 = 39.776 d5 = 0.9 1.6134 44.3 r6 = 8.778 L3 d6 = 4.63 1.4866 84.5 r7 = -6.945 d7 = 1.02 1.8807 41.0 r8 = -17.314 d8 = 0.19 to 1.48 r9 = 13.598 L4 d9 = 3.4 1.4866 84.5 r10 = -54.136 d10 = 13.85 to 20.30 r11 = 5.143 d11 = 3.87 1.4585 67.7 L5 r12 = -10.086 d12 = 1.24 1.6511 55.6 r13 = 3.927 __________________________________________________________________________ Cover-glass: 0 to 2 mm Working distance: W = 2.35 mm to 1.3 mm Linear magnification: β = 50 x Numerical aperture: A = 0.65.