Symmetrical copy lenses

Claim 2

A symmetrical lens having four singlet meniscus elements symmetrical about and concave toward a central stop, the first and second elements having radii, proceeding toward the center, R1, R2, R3, and R4, and thicknesses, proceeding toward said center, t1 and t2, said lenses being spaced apart by a space S1 and said second lens being spaced from said center by a space S2, said radii, thicknesses, and spaces being expressed as a fraction of the focal length f falling within the ranges listed below and said elements being of glass having characteristic refractive indices nD1 and nD2 and Abbe numbers v1 and v2 falling within the ranges listed in the table below: .207f < OR = R1 < OR = .217f .415f < OR = R2 < OR = .445f .198f < OR = R3 < OR = .215f .140f < OR = R4 < OR = 1.49f.044f < OR = t1 < OR = .052f.027f < OR = t2 < OR = .031f .0004f < OR = S1 < OR = .0006f .090f < OR = S2 < OR = 0.96f1.615 < OR = nD1 < OR = 1.6251.673 < OR = nD2 < OR = 1.72157.8 < OR = Nu 1 < OR = 62.827.8 < OR = Nu 2 < OR = 33.0

Claim 3

The lens of claim 1 having values substantially as listed below: R1.217f R2.435fR3.207fR4.147ft1.048ft2.030fS1.0004fS2.095fnD11.620nD21.72 0 Nu 160.3 Nu 229.3

Claim 4

The lens of claim 1 having values substantially as listed below: R1.217f R2.439fR3.213fR4.148ft1.051ft2.028fS1.0004fS2.093fnD11.620nD21.67 3 Nu 160.3 Nu 232.2

Claim 5

The lens of claim 1 having values substantially as listed below: R1.208fR2.416f R3.203fR4.143ft1.045ft2.028fS1.0005f S2.093fnD11.620nD21.720 Nu 160.3 Nu 229.3

Claim 6

The lens of claim 1 having values substantially as listed below: R1.211fR2.424fR3.204fR4.143ft1.046ft2.029fS1.0005fS2.092fnD11.620 nD21.720 Nu 160.3 Nu 229.3

Claim 7

The lens of claim 1 having values substantially as listed below: R1.211f R2.424f R3.203fR4.143ft1.045ft2.029f S1.0005f S2.093fnD11.620nD21.720 Nu 160.3 Nu 229.3

Claim 8

The lens of claim 1 having values substantially as listed below: R1.211fR2.424fR3.204f R4.143ft1.046ft2.029fS1.0005fS2.093fnD11.620 nD21.720 Nu 160.3 Nu 2 29.3

Claim 9

A retroreflective lens for use at oR near unit magnification having first and second singlet meniscus elements and a plano mirror, said elements being concave toward said mirror and having radii, proceeding toward said mirror, R1, R2, R3, R4, and thicknesses, proceeding toward said mirror, t1 and t2, said first element being separated from said second element by a space S1, and said second element being separated from said mirror by a space S2, said radii, thicknesses and spaces being expressed as a fraction of the focal length f, falling within the ranges listed below, and said elements being of glass having characteristic refractive indices, nD1 and nD2, and Abbe numbers Nu 1 and Nu 2, falling within the ranges listed in the table below: .207f < or = R1 < or = .217f.425f < or = R2 < or = .445f.198f < or = R3 < or = .215f.140f < or = R4 < or = .149f.044f < or = t1 < or = 0.52f.027f < or = t2 < or = .031f.0004f < or = S1 < or = .0006f.090f < or = S2 < or = .096f1.615 < or = nD1 < or = 1.6251.673 < or = nD2 < or = 1.721 57.8 < or = Nu 1 < or = 62.8 27.8 < or = Nu 2 < or = 33.0

Claim 10

A retroreflective lens for use at oR near unit magnification having first and second singlet meniscus elements and a plano mirror, said elements being concave toward said mirror and having radii, proceeding toward said mirror, R1, R2, R3, R4, and thicknesses, proceeding toward said mirror, t1 and t2, said first element being separated from said second element by a space S1, and said second element being separated from said mirror by a space S2, said radii, thicknesses and spaces being expressed as a fraction of the focal length f, falling within the ranges listed below, and said elements being of glass having characteristic refractive indices, nD1 and nD2, and Abbe numbers Nu 1 and Nu 2, falling within the ranges listed in the table below: .207f < or = R1 < or = .217f.425f < or = R2 < or = .445f.198f < or = R3 < or = .215f.140f < or = R4 < or = .149f.044f < or = t1 < or = 0.52f.027f < or = t2 < or = .031f.0004f < or = S1 < or = .0006f.090f < or = S2 < or = .096f1.615 < or = nD1 < or = 1.6251.673 < or = nD2 < or = 1.721 57.8 < or = Nu 1 < or = 62.8 27.8 < or = Nu 2 < or = 33.0

Claim 11

The lens of claim 8 having values substantially as listed below: R1.217f R2.435fR3.207fR4.147ft1.048ft2.030fS1.0004fS2.095fnD11.620nD21.72 0 Nu 160.3 Nu 229.3

Claim 12

The lens of claim 8 having values substantially as listed below: R1.217fR2.439fR3.213fR4.148ft1.051ft2.028fS1.0004fS2.093f nD11.620nD21.673 Nu 160.3 Nu 232.2

Claim 13

The lens of claim 8 having values substantially as listed below: R1.208fR2.416fR3.203fR4.143ft10.45ft2.028fS1.0005fS2.093fnD11.620 nD21.720 Nu 160.3 Nu 229.3

Claim 14

The lens of claim 8 having values substantially as listed below: R1.211fR2.424fR3.204fR4.143ft1.046ft20.29fS1.0005fS20.92fnD11.620 nD21.720 Nu 160.3 Nu 229.3

Claim 15

The lens of claim 8 having values substantially as listed below: R1.211fR2.424fR3.203fR4.143ft1.045ft2.029fS1.0005fS2.093fnD11.620 nD21.720 Nu 160.3 Nu 229.3

Claim 16

The lens of claim 8 having values substantially as listed below: R1.211fR2.424fR3.204fR4.143ft1.046ft2.029fS1.0005fS2.093fnD11.620 nD21.720 Nu 160.3 Nu 229.3

Claim 17

A symmetrical lens having four singlet meniscus elements symmetrical about and concave Toward a central stop, the first and second elements having radii, proceeding toward the center, R1, R2, R3 and R4, and thicknesses, proceeding toward said center, t1 and t2, said lenses being spaced apart by a space S1 and said second lens being spaced from said center by a space S2, said radii, thicknesses, and spaces being expressed as a fraction of the focal length f falling within the ranges listed below and said elements being of glass having characteristic refractive indices nD1 and nD2 and Abbe numbers Nu 1 and Nu 2 falling within the ranges listed in the table below: .028f < or = R1 < or = .217f.416f < or = R2 < or = .439f.203f < or = R3 < or = .213f.143f < or = R4 < or = .148f0.45f < or = t1 < or = .051f0.28f < or = t2 < or = .030f.0004f < or = S1 < or = .0005f.092f < or = S2 < or = .095f1.620 Congruent nD11.673 < or = nD2 < or = 1.72060.3 Congruent Nu 1 29.3 < or = Nu 2 < or = 32.2

Claim 18

A symmetrical lens having four singlet meniscus elements symmetrical about and concave Toward a central stop, the first and second elements having radii, proceeding toward the center, R1, R2, R3 and R4, and thicknesses, proceeding toward said center, t1 and t2, said lenses being spaced apart by a space S1 and said second lens being spaced from said center by a space S2, said radii, thicknesses, and spaces being expressed as a fraction of the focal length f falling within the ranges listed below and said elements being of glass having characteristic refractive indices nD1 and nD2 and Abbe numbers Nu 1 and Nu 2 falling within the ranges listed in the table below: .028f < or = R1 < or = .217f.416f < or = R2 < or = .439f.203f < or = R3 < or = .213f.143f < or = R4 < or = .148f0.45f < or = t1 < or = .051f0.28f < or = t2 < or = .030f.0004f < or = S1 < or = .0005f.092f < or = S2 < or = .095f1.620 Congruent nD11.673 < or = nD2 < or = 1.72060.3 Congruent Nu 1 29.3 < or = Nu 2 < or = 32.2

Claim 19

A retroreflective lens for use at or near unit magnification having first and second singlet meniscus elements and a plano mirror, said elements being concave toward said mirror and having radii, proceeding toward said mirror, R1, R2, R3, and R4, and thicknesses, proceeding toward said mirror, t1 and t2, said first element being separated from said second element by a space S1, and said second element being separated from said mirror by a space S2, said radii, thicknesses and spaces being expressed as a fraction of the focal length f, falling within the ranges listed below, and said elements being of glass having characteristic refractive indices, nD1 and nD2, and Abbe numbers Nu 1 and Nu 2, falling within the ranges listed in the table below. .208f < or = R1 < or = .217f.416f < or = R2 < or = .439f.203f < or = R3 < or = .213f.143f < or = R4 < or = .148f.045f < or = t1 < or = .051f.028f < or = t2 < or = .030f.0004f < or = S1 < or = .0005f.092f < or = S2 < or = .095f1.620 Congruent nD11.673 < or = nD2 < or = 1.72060.3 Congruent Nu 1 29.3 < or = Nu 2 < or = 32.2

Claim 20

A retroreflective lens for use at or near unit magnification having first and second singlet meniscus elements and a plano mirror, said elements being concave toward said mirror and having radii, proceeding toward said mirror, R1, R2, R3, and R4, and thicknesses, proceeding toward said mirror, t1 and t2, said first element being separated from said second element by a space S1, and said second element being separated from said mirror by a space S2, said radii, thicknesses and spaces being expressed as a fraction of the focal length f, falling within the ranges listed below, and said elements being of glass having characteristic refractive indices, nD1 and nD2, and Abbe numbers Nu 1 and Nu 2, falling within the ranges listed in the table below. .208f < or = R1 < or = .217f.416f < or = R2 < or = .439f.203f < or = R3 < or = .213f.143f < or = R4 < or = .148f.045f < or = t1 < or = .051f.028f < or = t2 < or = .030f.0004f < or = S1 < or = .0005f.092f < or = S2 < or = .095f1.620 Congruent nD11.673 < or = nD2 < or = 1.72060.3 Congruent Nu 1 29.3 < or = Nu 2 < or = 32.2