Cryptographically coded cards employing synthetic light modifying portion

Claim 2

In a cryptographically coded card of the type employing a light-modifying portion responsive to the illumination thereof with a single incident light beam for deriving a particular subset of a given set of output light beams in accordance with a cryptographic code manifested by said light-modifying portion of the illuminated card; the improvement wherein said lightmodifying portion includes a plurality of discrete subareas parallel to a given plane each of which is occupied by an assigned one of a group Of different predetermined lightmodifying forms, each separate subarea being responsive to the illumination thereof by light for deriving an output light beam at that one of a unique plurality of discrete inclination angles with the normal to said given plane determined by the assigned form occupying that subarea.

Claim 3

The cryptographically coded card defined in claim 1, wherein each of said group of forms is shaped to possess some one of a set of discrete angular orientations about said normal, and wherein the particular form occupying any respective one of said subareas is oriented at an assigned one of a second group of predetermined meridional angles about said normal.

Claim 4

The cryptographically coded card defined in claim 2, wherein more than one subarea is assigned both the same form from said first-mentioned group and the same meridional angle from said second group.

Claim 5

The cryptographically coded card defined in claim 3, wherein said plurality of subareas is equal in number to the product of first and second plural integers, and any given one of said forms at any given one of said meridional angles is assigned to a number of said subareas equal to said first integer, whereby the total number of assignments differing either in form or meridional angle is equal to said second integer.

Claim 6

The cryptographically coded card defined in claim 4, wherein the relative positions of said assigned subareas with respect to each other is randomly distributed in said plane.

Claim 7

The cryptographically coded card defined in claim 2, wherein said cryptographic code is a binary code having a given number of bit positions, wherein said first group of different forms includes a first predetermined form manifesting a binary ONE and a second predetermined form manifesting a binary ZERO, and wherein said second group of different meridional angles includes a separate predetermined meridional angle manifesting each different bit position of said crytographic code.

Claim 8

The cryptographically coded card defined in claim 1, wherein said light-modifying portion comprises a transparent material having a different index of refraction from its surroundings, said material including two opposed surfaces thereof one of which has said group of forms embossed thereon and the other of which lies in a plane substantially parallel to said given plane.

Claim 9

The cryptographically coded card defined in claim 7, wherein each of said different forms comprises a portion of said one surface inclined at a different predetermined angle with respect to said normal, whereby each of said different forms defines a prism having a different respective angle of inclination and each of said subareas is occupied by an assigned one of said prisms.

Claim 10

The cryptographically coded card defined in claim 8, wherein all of said group of prisms are circularly assymetrical about said normal, and wherein the particular prism embossed on any respective one of said subareas occupies an assigned one of a second group of predetermined meridional angles about said normal.

Claim 11

The cryptographically coded card defined in claim 9, wherein more than one subarea is assigned both the same prism from said first-mentioned group and the same meridional angle from said second group.

Claim 12

The cryptographically coded card defined in claim 10, wherein said plurality of subareas is equal in number to the product of first and second plural integers, and any given one of said prisms at any given one of said meridional angles is assigned to a number of said subareas equal to said first integer, whereby the total number of assignments differing either in prism or meridional angle is equal to said second integer.

Claim 13

The cryptographically coded card defined in claim 11, wherein the relative positions of said assigned subareas with respect to each other is randomly distributed in said plane.

Claim 14

The cryptographically coded card defined in claim 12, wherein said cryptographic code is a binary code having a given number of bIt positions wherein said first group of different prisms includes a first predetermined prism manifesting a binary ONE and a second predetermined prism manifesting a binary ZERO, and wherein said second group of different meridional angles includes a separate predetermined meridional angle manifesting each different bit position of said cryptographic code.

Claim 15

The cryptrographically coded card defined in claim 7, wherein said material encloses a region having a different index of refraction therefrom, said one surface of said material being situated at an interface between said material and said region.

Claim 16

A decoder for decoding cryptographically coded cards: a. wherein each card comprises a light-modifying portion which includes a given plurality of discrete subareas parallel to a given plane each of which is occupied by an assigned one of a first group of different predetermined light-modifying forms shaped to possess some one of a set of discrete angular orientations, each form being oriented at an assigned one of a second group of different meridional angles about the normal to that subarea said assignments being made in accordance the code of that card, each separate subarea being responsive to the illumination thereof with light for deriving an output light beam at that one of a plurality of discrete inclination angles with said normal determined by the assigned form occupying that subarea and at that one of a plurality of discrete meridional angles about said normal determined by the assigned orientation of the assigned form occupying that subarea, and wherein more than one subarea is assigned both the same form from said first group and the same meridional angle from said second group; and b. wherein said decoder comprises a light source illuminating the light-modifying portion of a cryptographically coded card to be decoded for deriving respective output light beams from each of said subareas which have respective angles of inclination with said normal and respective meridional angles about said normal determined by both the assigned form and assigned orientation thereof occupying the subarea from which each of said respective output beams is derived, imaging means situated in predetermined spaced relationship with respect to said card to be decoded and illuminated by all of said respective output beams for focusing those output beams which have both the same inclination angle and the same meridional angle as each other to the same focal point and for focusing those output beams which have different inclination angles and/or different meridional angles to different given focal points so that the card then being illuminated is represented by the spatial distribution of said focal points, and means including light sensors responsive to the spatial distribution of said focal points for ascertaining of the card then being illuminated.

Claim 17

A decoder for decoding cryptographically coded cards: a. wherein each card comprises a light-modifying portion which includes a given plurality of discrete subareas parallel to a given plane each of which is occupied by an assigned one of a first group of different predetermined light-modifying forms shaped to possess some one of a set of discrete angular orientations, each form being oriented at an assigned one of a second group of different meridional angles about the normal to that subarea said assignments being made in accordance the code of that card, each separate subarea being responsive to the illumination thereof with light for deriving an output light beam at that one of a plurality of discrete inclination angles with said normal determined by the assigned form occupying that subarea and at that one of a plurality of discrete meridional angles about said normal determined by the assigned orientation of the assigned form occupying that subarea, and wherein more than one subarea is assigned both the same form from said first group and the same meridional angle from said second group; and b. wherein said decoder comprises a light source illuminating the light-modifying portion of a cryptographically coded card to be decoded for deriving respective output light beams from each of said subareas which have respective angles of inclination with said normal and respective meridional angles about said normal determined by both the assigned form and assigned orientation thereof occupying the subarea from which each of said respective output beams is derived, imaging means situated in predetermined spaced relationship with respect to said card to be decoded and illuminated by all of said respective output beams for focusing those output beams which have both the same inclination angle and the same meridional angle as each other to the same focal point and for focusing those output beams which have different inclination angles and/or different meridional angles to different given focal points so that the card then being illuminated is represented by the spatial distribution of said focal points, and means including light sensors responsive to the spatial distribution of said focal points for ascertaining of the card then being illuminated.

Claim 18

The decoder defined in claim 15, wherein said imaging means is a convex lens having a given focal length and having its focal plane oriented substantially parallel to said given plane, and wherein the direction of the light from said light source incident on said subareas is at least paraxial with respect to said normal thereto, whereby said focal points all lie in an image plane of said lens.

Claim 19

The decoder defined in claim 16, wherein said incident light has a plane wavefront; whereby said image plane is the focal plane of said lens.

Claim 20

The decoder defined in claim 16, wherein said plurality of subareas is equal in number to the product of first and second plural integers, and any given one of said forms at any given one of said meridional angles is assigned to a number of said subareas equal to said first integer, whereby the total number of assignments differing either in form or meridional angle and the total number of different focal points is equal to said second integer.

Claim 21

The decoder defined in claim 18, wherein sadi cryptographic code is a binary code having a given number of bit pOsitions, wherein said first group of different forms includes a first predetermined form manifesting a binary ONE and a second predetermined form manifesting a binary ZERO, and wherein said second group of different meridional angles includes a separate predetermined meridional angle manifesting each different bit position of said cryptographic code, whereby each bit position is represented by a separate focal point in said image plane with all of those focal points representing bits manifesting a binary ONE lying on the circumference of a first-radius circle and all those focal points representing bits manifesting a binary ZERO lying on a second-radius circle.

Claim 22

The decoder defined in claim 15, wherein said plurality of subareas is equal in number to the product of first and second plural integers, and any given one of said forms at any given one of said meridional angles is assigned to a number of said subareas equal to said first integer, whereby the total number of assignments differing either in form or meridional angle and the total number of different focal points is equal to said second integer.