Optical arrangement for comparing the visual characteristics of similar objects

Claim 2

An arrangement for comparing the visual characteristics of two similar objects, particularly masks used in the fabrication of integrated circuits from wafers of semiconductor material, comprising, in combination: first optical means arranged for forming, from an object located at a predetermined first object location, a first image located at a predetermined image location; second optical means arranged for forming, from an object located at a predetermined second object location, a second image located at a predetermined image location; and third optical means arranged for forming, from said first and second images, real and coincident respective third and fourth images, said third optical means comprising a concave mirror positioned to receive and reflect said first and second images to form focussed real and coincident images constituting said third and fourth images.

Claim 3

An arrangement as defined in claim 1, wherein said first optical means comprises means arranged for forming from an object located at said first object location a virtual image constituting said first image, and wherein said second optical means comprises means arranged for forming from an object located at said second object location a virtual image constituting said second image.

Claim 4

An arrangement as defined in claim 1, wherein said first optical means comprises means arranged for forming from an object located at said first object location a virtual image constituting said first image, and wherein said second optical means comprises means arranged for forming from an object located at said second object location a virtual image coincident with said first image and constituting said second image.

Claim 5

An arrangement as defined in claim 1, wherein said concave mirror is a spherical concave mirror.

Claim 6

An arrangement as defined in claim 1, wherein at least one of said optical means comprise at least one prismatic body of refracting material intervening between said coincident virtual images and said concave mirror.

Claim 7

An arrangement as defined in claim 1, wherein at least one of said first, second and third optical means comprises a prismatic body of refracting material, and wherein said coincident real images are located in free space and not within said refracting material.

Claim 8

A method as defined in claim 1, and further including a magnifying instrument for magnifying said coincident real images.

Claim 9

An arrangement for comparing the visual characteristics of two similar objects, particularly masks used in the fabrication of integrated circuits from wafers of semiconductor material, comprising in combination: first optical means arranged for forming, from an object located at a predetermined first object location, a first image located at a predetermined image location; second optical means arranged for forming, from an object located at a predetermined second object location, a second image located at a predetermined image location; and third optical means arranged for forming, from said first and second images, real and coincIdent respective third and fourth images, wherein at least one of said first, second and third optical means comprises a prismatic body of refracting material having an outer boundary surface; and further including a magnifying instrument including an object glass and having a predetermined operational distance measured with respect to said object glass at which an object or image to be magnified must be located for said magnifying instrument to form a focused magnified image of such object or image to be magnified, andd wherein said coincident real images are located within said refracting material at such a distance from said outer boundary surface that the refracting material intervening between said outer boundary surface and said coincident real images results in the formation of two derived coincident virtual images visible from a location outside said refracting material in the vicinity of said boundary surface and located within said refracting material at a distance from said boundary surface no greater than said operational distance of said magnifying instrument, so that said derived coincident virtual images can be explored by said magnifying instrument.

Claim 10

An arrangement for comparing the visual characteristics of two similar objects, particularly masks used in the fabrication of integrated circuits from wafers of semiconductor material, comprising in combination: first optical means arranged for forming, from an object located at a predetermined first object location, a first image located at a predetermined image location; second optical means arranged for forming, from an object located at a predetermined second object location, a second image located at a predetermined image location; and third optical means arranged for forming, from said first and second images, real and coincIdent respective third and fourth images, wherein at least one of said first, second and third optical means comprises a prismatic body of refracting material having an outer boundary surface; and further including a magnifying instrument including an object glass and having a predetermined operational distance measured with respect to said object glass at which an object or image to be magnified must be located for said magnifying instrument to form a focused magnified image of such object or image to be magnified, andd wherein said coincident real images are located within said refracting material at such a distance from said outer boundary surface that the refracting material intervening between said outer boundary surface and said coincident real images results in the formation of two derived coincident virtual images visible from a location outside said refracting material in the vicinity of said boundary surface and located within said refracting material at a distance from said boundary surface no greater than said operational distance of said magnifying instrument, so that said derived coincident virtual images can be explored by said magnifying instrument.

Claim 11

An arrangement for comparing the visual characteristics of two similar objects, particularly masks used in the fabrication of intergrated circuits from wafers of semiconductor material, comprising in combination: first optical means arranged for forming, from an object located at a predetermined first object location, a first image located at a predetermined image location; second optical means arranged for forming, from an object located at a predetermined second object location, a second image located at a predetermined image location; and third optical means arranged for forming, from said first and second images, real and coincident respective third and fourth images, wherein at least one of said first, second and third optical means comprises a prismatic body of refracting material having an outer boundary surface constituting an interface between refracting material and free space, and wherein said coincident real images are located substantially coincident with said outer boundary surface.

Claim 12

An arrangement for comparing the visual characteristics of two similar objects, particularly masks used in the fabrication of intergrated circuits from wafers of semiconductor material, comprising in combination: first optical means arranged for forming, from an object located at a predetermined first object location, a first image located at a predetermined image location; second optical means arranged for forming, from an object located at a predetermined second object location, a second image located at a predetermined image location; and third optical means arranged for forming, from said first and second images, real and coincident respective third and fourth images, wherein at least one of said first, second and third optical means comprises a prismatic body of refracting material having an outer boundary surface constituting an interface between refracting material and free space, and wherein said coincident real images are located substantially coincident with said outer boundary surface.

Claim 13

An arrangement for comparing the visual characteristics of two similar objects, particularly masks used in the fabrication of integrated circuits from wafers of semiconductor material, comprising in combination: first optical means arranged for forming, from an object located at a predetermined first object location, a first image located at a predetermined image location; second optical means arranged for forming, from an object located at a predetermined second object location, a second image located at a predetermined image location; and third optical means arranged for forming, from said first and second images, real and coincident respective third and fourth images, wherein at least one of said first, second and third optical means comprises a prismatic body of refracting material having an outer boundary surface constituting an interface between refracting material and free space, and wherein said coincident real images are located within said refracting material.

Claim 14

An arrangement for comparing the visual characteristics of two similar objects, particularly masks used in the fabrication of integrated circuits from wafers of semiconductor material, comprising in combination: first optical means arranged for forming, from an object located at a predetermined first object location, a first image located at a predetermined image location; second optical means arranged for forming, from an object located at a predetermined second object location, a second image located at a predetermined image location; and third optical means arranged for forming, from said first and second images, real and coincident respective third and fourth images, wherein at least one of said first, second and third optical means comprises a prismatic body of refracting material having an outer boundary surface constituting an interface between refracting material and free space, and wherein said coincident real images are located within said refracting material.

Claim 15

An arrangement for comparing the visual characteristics of two similar objects, particularly masks used in the fabrication of integrated circuits from wafers of semiconductor material, comprising in combination: first optical means arranged for forming, from an object located at a predetermined first object location, a first image located at a predetermined image location; second optical means arranged for forming, from an object located at a predetermined second object location, a second image located at a predetermined image location; and third optical means arranged for forming, from said first and second images, real and coincident respective third and fourth images; and further including registering means comprising a first pivotably mounted plane-parallel plate of refracting material located in the path of light rays travelling toWards said first optical means from an object located at said first object location and so arranged that rotation of said first plate effects translation of such light rays in a sense producing relative translation between said real images in a predetermined first direction, and a second pivotably mounted plane-parallel plate of refracting material located in the path of light rays travelling towards said second optical means from an object located at said second object location and so arranged that rotation of said second plate effects translation of such light rays in a sense producing relative translation between said real images in a predetermined second direction perpendicular to said first direction.

Claim 16

An arrangement for comparing the visual characteristics of two similar objects, particularly masks used in the fabrication of integrated circuits from wafers of semiconductor material, comprising in combination: first optical means arranged for forming, from an object located at a predetermined first object location, a first image located at a predetermined image location; second optical means arranged for forming, from an object located at a predetermined second object location, a second image located at a predetermined image location; and third optical means arranged for forming, from said first and second images, real and coincident respective third and fourth images; and further including registering means comprising a first pivotably mounted plane-parallel plate of refracting material located in the path of light rays travelling toWards said first optical means from an object located at said first object location and so arranged that rotation of said first plate effects translation of such light rays in a sense producing relative translation between said real images in a predetermined first direction, and a second pivotably mounted plane-parallel plate of refracting material located in the path of light rays travelling towards said second optical means from an object located at said second object location and so arranged that rotation of said second plate effects translation of such light rays in a sense producing relative translation between said real images in a predetermined second direction perpendicular to said first direction.

Claim 17

An arrangement for comparing the visual characteristics of two similar objects, particularly two masks of the type used in the fabrication of integrated circuits from wafers of semiconductor material, comprising in combination: optical means arranged for forming, from an objected located at a predetermined first object location, a first real image located at a respective predetermined image location; additional optical means arranged for forming, from an object located at a predetermined second object location, a virtual image located at a respective predetermined image location; and further optical means arranged for forming, from said virtual image, a second real image coincident with said first real image, said further optical means comprising a concave mirror positioned to receive and reflect said virtual image to form a focussed real image coincident with said first real image and constituting said second real image.

Claim 18

An arrangement for comparing the visual characteristics of two similar objects, particularly two masks of the type used in the fabrication of integrated circuits from wafers of semiconductor material, comprising in combination: optical means arranged for forming, from an objected located at a predetermined first object location, a first real image located at a respective predetermined image location; additional optical means arranged for forming, from an object located at a predetermined second object location, a virtual image located at a respective predetermined image location; and further optical means arranged for forming, from said virtual image, a second real image coincident with said first real image, said further optical means comprising a concave mirror positioned to receive and reflect said virtual image to form a focussed real image coincident with said first real image and constituting said second real image.