Objective lens system with aspheric Fresnel elements

Claim 2

A high speed objective lens system capable of forming images that is particularly adaptable for a television projection system comprising from a viewing screen object side to a video image side on an optical axis; a first thin meniscus lens element convex to the object side having a curvilinear configuration on one side and a Fresnel type surface on the other side; a second thin meniscus lens element concave to the object side having a curvilinear configuration on one side and a Fresnel type surface on the other side, and a third weak thin aspherical meniscus lens element convex to the object side.

Claim 3

The invention of claim 1 wherein each of the Fresnel surfaces have a locus of median points of their respective step facets that form a nonplanar configuration.

Claim 4

The invention of claim 1 wherein the object side of the third lens includes an aspherical surface.

Claim 5

The invention of claim 1 wherein the third lens has one surface having a curvilinear configuration on one side and a Fresnel type surface on the other side.

Claim 6

The invention of claim 1 wherein the effective diameter of each lens is at least twenty times greater than its maximum thickness.

Claim 7

The invention of claim 1 wherein the slopes of step facets forming the Fresnel surfaces are aspherical.

Claim 8

The invention of claim 1 wherein each lens element has the same thickness on the optical axis.

Claim 9

The invention of claim 1 wherein each lens is formed from a plastic material.

Claim 10

The invention of claim 8 wherein each lens is formed from an acrylic plastic.

Claim 11

The invention of claim 1 wherein the speed of the lens system is greater than or equal to F/1.9.

Claim 12

In a video projection system having a projection screen and an image forming surface, the improvement comprising; a high speed objective projection lens assembly operatively positioned relative to the image forming surface for projecting the images onto the screen including a first thin meniscus lens element convex to the projection screen, a second thin meniscus lens element concave to the projection screen, and a third thin lens element, at least one surface on each of two lens elements have a Fresnel type surface, the locus of median points of respective step facets of each Fresnel type surface forming a nonplanar configuration.

Claim 13

In a video projection system having a projection screen and an image forming surface, the improvement comprising; a high speed objective projection lens assembly operatively positioned relative to the image forming surface for projecting the images onto the screen including a first thin meniscus lens element convex to the projection screen, a second thin meniscus lens element concave to the projection screen, and a third thin lens element, at least one surface on each of two lens elements have a Fresnel type surface, the locus of median points of respective step facets of each Fresnel type surface forming a nonplanar configuration.

Claim 14

The invention of claim 11 wherein the slopes of the step facets of the Fresnel surface are aspherical.

Claim 15

The invention of claim 11 wherein each of the meniscus lens elements have one aspherical Fresnel facet surface.

Claim 16

The invention of claim 11 wherein the effective diameter of each lens is at least twenty times greater than its maximum thickness.

Claim 17

The invention of claim 11 wherein each lens element has the same thickness on the optical axis.

Claim 18

The invention of claim 11 wherein each lens is formed from a plastic material.

Claim 19

The invention of claim 11 wherein the speed of the lens system is greater than or equal to F/1.9.

Claim 20

The invention of claim 16 wherein each lens is formed from an acrylic plastic.

Claim 21

A high speed plastic objective lens system comprising from image to object side; a first thin meniscus lens element convex to the image side; a second thin meniscus lens element concave to the image side; a third thin lens element, at least one surface on each of two lens elements have a Fresnel surface, the locus of median points of respective step facets of each Fresnel surface forming a nonplanar configuration.

Claim 22

A high speed plastic objective lens system comprising from image to object side; a first thin meniscus lens element convex to the image side; a second thin meniscus lens element concave to the image side; a third thin lens element, at least one surface on each of two lens elements have a Fresnel surface, the locus of median points of respective step facets of each Fresnel surface forming a nonplanar configuration.

Claim 23

The invention of claim 19 wherein the locus of median points traces a cross-sectional circular path.

Claim 24

The invention of claim 19 wherein the slopes of step facets forming each Fresnel surface is aspherical.

Claim 25

The invention of claim 19 wherein the lens element is molded from a plastic material.

Claim 26

The invention of claim 19 wherein the object side surface of the third lens element is convex to the image side.

Claim 27

The invention of claim 19 wherein the effective diameter of each lens is at least twenty times greater than its maximum thickness.

Claim 28

The invention of claim 24 wherein each Fresnel refracting surface is aspherical.

Claim 29

The invention of claim 25 wherein at least one refracting surface on each lens element is aspherical.

Claim 30

The invention of claim 25 wherein the speed of the lens system is at least F/1.9.

Claim 31

The invention of claim 25 wherein the locus of the median points has a base radius, RB, which is within a range of 0.53 to 20 times the diameter of the lens elements with the Fresnel refracting surface.

Claim 32

A high speed plastic objective lens system comprising the following design parameters; __________________________________________________________________________ ELEMENT R1 R2 T N/V __________________________________________________________________________ OBJECT DISTANCE 57.4401 L.sub.1 A(1) 5.3957 0.900 1.491/57.2 RB.sub.1 = 6.685 2.8223 APERTURE STOP 2.5535 L.sub.2 A(2) RB.sub.2 = -2.6328 -2.7674 .0900 1.491/57.2 .8591 L.sub.3 A(3) RB.sub.3 = 21.744 13.2925 .0900 1.491/57.2 IMAGE 8.0552 ASPHERIC CONSTANTS ##STR4## ASPHERIC CURVATURE K A B __________________________________________________________________________ A(1) .28380247 0.000000 -9.31229E -4 -5.36759E -4 A(2) -.12935331 0.000000 -1.85253E -2 7.55302E -4 A(3) -.03567578 0.000000 1.44629E -2 -1.63779E -3 __________________________________________________________________________ C D __________________________________________________________________________ 6.38404E -5 -5.05445E -6 5.339075E -5 -2.961245E -5 1.11646E -4 -3.29334E -6 __________________________________________________________________________

Claim 33

A high speed plastic objective lens system comprising the following design parameters; __________________________________________________________________________ ELEMENT R1 R2 T N/V __________________________________________________________________________ OBJECT DISTANCE 57.4401 L.sub.1 A(1) 5.3957 0.900 1.491/57.2 RB.sub.1 = 6.685 2.8223 APERTURE STOP 2.5535 L.sub.2 A(2) RB.sub.2 = -2.6328 -2.7674 .0900 1.491/57.2 .8591 L.sub.3 A(3) RB.sub.3 = 21.744 13.2925 .0900 1.491/57.2 IMAGE 8.0552 ASPHERIC CONSTANTS ##STR4## ASPHERIC CURVATURE K A B __________________________________________________________________________ A(1) .28380247 0.000000 -9.31229E -4 -5.36759E -4 A(2) -.12935331 0.000000 -1.85253E -2 7.55302E -4 A(3) -.03567578 0.000000 1.44629E -2 -1.63779E -3 __________________________________________________________________________ C D __________________________________________________________________________ 6.38404E -5 -5.05445E -6 5.339075E -5 -2.961245E -5 1.11646E -4 -3.29334E -6 __________________________________________________________________________

Claim 34

A high speed plastic objective lens system comprising the following design parameters; __________________________________________________________________________ ELEMENT R1 R2 T N/V __________________________________________________________________________ OBJECT DISTANCE 57.4401 L.sub.1 A(1) 5.3957 0.900 1.491/57.2 RB.sub.1 = 6.685 2.8223 APERTURE STOP 2.5535 L.sub.2 A(2) RB.sub.2 = -2.6328 -2.7674 .0900 1.491/51.2 .8591 L.sub.3 A(3) RB.sub.3 = 21.744 13.2925 .0900 1.491/57.2 IMAGE 8.0552 ASPHERIC CONSTANTS ##STR5## __________________________________________________________________________ ASPHERIC CURVATURE K A B __________________________________________________________________________ A(1) .28380247 0.000000 -9.31229E -4 -5.36759E -4 A(2) -.12935331 0.000000 -1.85253E -2 7.55302E -4 A(3) -.03580302 0.000000 1.46732E -2 -1.67730E -3 __________________________________________________________________________ C D __________________________________________________________________________ 6.38404E -5 -5.05445E -6 5.33907E -5 -2.96124E -5 1.12721E -4 -3.22124E -6 __________________________________________________________________________

Claim 35

A high speed plastic objective lens system comprising the following design parameters; __________________________________________________________________________ ELEMENT R1 R2 T N/V __________________________________________________________________________ OBJECT DISTANCE 57.4401 L.sub.1 A(1) 5.3957 0.900 1.491/57.2 RB.sub.1 = 6.685 2.8223 APERTURE STOP 2.5535 L.sub.2 A(2) RB.sub.2 = -2.6328 -2.7674 .0900 1.491/51.2 .8591 L.sub.3 A(3) RB.sub.3 = 21.744 13.2925 .0900 1.491/57.2 IMAGE 8.0552 ASPHERIC CONSTANTS ##STR5## __________________________________________________________________________ ASPHERIC CURVATURE K A B __________________________________________________________________________ A(1) .28380247 0.000000 -9.31229E -4 -5.36759E -4 A(2) -.12935331 0.000000 -1.85253E -2 7.55302E -4 A(3) -.03580302 0.000000 1.46732E -2 -1.67730E -3 __________________________________________________________________________ C D __________________________________________________________________________ 6.38404E -5 -5.05445E -6 5.33907E -5 -2.96124E -5 1.12721E -4 -3.22124E -6 __________________________________________________________________________

Claim 36

A high speed plastic objective lens system comprising the following design parameters; __________________________________________________________________________ ELEMENT R1 R2 T N/V __________________________________________________________________________ OBJECT DISTANCE 73.5468 L.sub.1 A(1) 13.5990 0.900 1.491/57.2 RB.sub.1 = 16.474 4.9097 APERTURE STOP 4.6420 L.sub.2 A(2) -4.1397 .0900 1.491/57.2 RB.sub.2 = -3.784 1.1783 L.sub.3 A(3) 26.0000 .0900 1.491/57.2 RB.sub.3 = 34.846 IMAGE 8.2004 ASPHERIC CONSTANTS ##STR6## ASPHERIC CURVATURE K A B __________________________________________________________________________ A(1) .17086590 0.000000 -3.65390E -4 -2.22403E -5 A(2) -.07207025 0.000000 -7.02038E -3 +2.17572E -4 A(3) -.04295470 0.000000 5.87983E -3 -3.05549E -4 __________________________________________________________________________ C D __________________________________________________________________________ 6.51163E -7 -2.70110E -8 -5.84082E -6 -6.19676E -7 9.46927E -6 -1.24323E -7 __________________________________________________________________________

Claim 37

A high speed plastic objective lens system comprising the following design parameters; __________________________________________________________________________ ELEMENT R1 R2 T N/V __________________________________________________________________________ OBJECT DISTANCE 73.5468 L.sub.1 A(1) 13.5990 0.900 1.491/57.2 RB.sub.1 = 16.474 4.9097 APERTURE STOP 4.6420 L.sub.2 A(2) -4.1397 .0900 1.491/57.2 RB.sub.2 = -3.784 1.1783 L.sub.3 A(3) 26.0000 .0900 1.491/57.2 RB.sub.3 = 34.846 IMAGE 8.2004 ASPHERIC CONSTANTS ##STR6## ASPHERIC CURVATURE K A B __________________________________________________________________________ A(1) .17086590 0.000000 -3.65390E -4 -2.22403E -5 A(2) -.07207025 0.000000 -7.02038E -3 +2.17572E -4 A(3) -.04295470 0.000000 5.87983E -3 -3.05549E -4 __________________________________________________________________________ C D __________________________________________________________________________ 6.51163E -7 -2.70110E -8 -5.84082E -6 -6.19676E -7 9.46927E -6 -1.24323E -7 __________________________________________________________________________