1. A method, comprising:
selecting, at a first application at a first device, one of a plurality of encapsulation format types based on a cost or bandwidth associated with a network, or associated with a link of the network, connected between the first application at the first device and a second application at a second device,
wherein each of the plurality of encapsulation format types comprises session layer encapsulation having different quantities of data overhead, and
wherein the plurality of encapsulation format types comprise a first encapsulation format type having a first quantity of data overhead and a second encapsulation format type having a second quantity of data overhead, wherein the first quantity of data overhead is greater than the second quantity of data overhead;
receiving, at the first application from Open Systems Interconnection (OSI) layers above an OSI session layer, payload data associated with a session;
generating one or more session layer encapsulated blocks of the payload data using the selected one of the plurality of encapsulated format types;
encrypting the payload data, and other data of the one or more session layer encapsulated blocks; and
passing the encrypted session layer encapsulated block to OSI layers below the session layer for sending to the second application.
2. The method of claim 1, wherein the session comprises a sequence of data units between the first application and the second application.
3. The method of claim 1, wherein the plurality of encapsulation format types further comprise a third encapsulation format type having a third quantity of data overhead, where the third quantity of data overhead is greater than the first quantity of data overhead and the second quantity of data overhead.
4. The method of claim 1, further comprising:
indexing a security policy database with a session identifier to retrieve data that selects the one of the plurality of encapsulation format types.
5. A device, comprising:
a communication interface connected to a network;
a processing unit configured to execute a first application and to:
select one of a plurality of encapsulation format types based on a cost or bandwidth associated with the network, or associated with a link of the network, connected between the first application at the first network device and a second application at a second network device,
wherein each of the plurality of encapsulation format types comprises session layer encapsulation having different quantities of data overhead, and
wherein the plurality of encapsulation format types comprise a first encapsulation format type having a first quantity of data overhead and a second encapsulation format type having a second quantity of data overhead, wherein the first quantity of data overhead is greater than the second quantity of data overhead,
receive, at the first application from Open Systems Interconnection (OSI) layers above a OSI session layer, payload data associated with a session, wherein the session comprises a sequence of data units between the first application and the second application,
generate one or more session layer encapsulated blocks of the payload data using the selected one of the plurality of encapsulated format types;
encrypt the payload data, and other data of the one or more session layer encapsulated blocks; and
pass the encrypted session layer encapsulated block to OSI layers below the session layer for sending to the second application via the communication interface.
6. The device of claim 5, wherein the device comprises a cellular telephone, a personal digital assistant (PDA), or a tablet, desktop, palmtop, or laptop computer.
7. The device of claim 5, wherein the plurality of encapsulation format types further comprise a third encapsulation format type having a third quantity of data overhead, where the third quantity of data overhead is greater than the first quantity of data overhead and the second quantity of data overhead.
8. The device of claim 7, wherein the plurality of encapsulation format types further comprise a fourth encapsulation format type having a fourth quantity of data overhead, where the fourth quantity of data overhead is greater than the first quantity of data overhead, the second quantity of data overhead, and the third quantity of data overhead.
9. The device of claim 5, wherein the processing unit is further configured to execute the first application and to:
index a security policy database with a session identifier to retrieve data that selects the one of the plurality of encapsulation format types.
10. A method, comprising:
determining, at a first application at a first device, a session identity for a session between the first application and a second application at a second device;
generating a security parameters index (SPI) for the session;
negotiating, between the first application and the second application, a selected session layer encapsulation format type, from among multiple different session layer encapsulation format types, based on a cost or bandwidth associated with a network, or associated with a link of the network, connected between the first device and the second device,
wherein each of the multiple different session layer encapsulation format types comprises session layer encapsulation having different quantities of data overhead, and
wherein the multiple different session layer encapsulation format types comprise a first encapsulation format type having a first quantity of data overhead and a second encapsulation format type having a second quantity of data overhead, wherein the first quantity of data overhead is greater than the second quantity of data overhead; and
creating an entry for the session in a security policy database (SPD), wherein the entry includes the session identity, the SPI, and the selected session layer encapsulation format type.
11. The method of claim 10, further comprising:
exchanging the SPI with the second application.
12. The method of claim 10, further comprising:
negotiating, between the first application and the second application, a ciphersuite for encrypting data session layer data between the first application and the second application.
13. The method of claim 12, further comprising:
obtaining, at the first application based on the negotiated ciphersuite, an encryption key for the session.
14. The method of claim 10, further comprising:
obtaining, at the first application, an encryption key for the session.
15. The method of claim 10, further comprising:
negotiating, between the first application and the second application, a ciphersuite for encrypting data session layer data between the first application and the second application;
obtaining, at the first application based on the negotiated ciphersuite, an encryption key for the session,
wherein the entry for the session in the SPD further includes the ciphersuite and the encryption key.
16. A device, comprising:
one or more communication interfaces connected to a network and to a security policy database (SPD);
a processing unit configured to execute a first application and to:
determine, by the first application, a session identity for a session between the first application and a second application at a second device,
generate a security parameters index (SPI) for the session,
negotiate, between the first application and the second application via the one or more communication interfaces, a selected session layer encapsulation format type, from among multiple different session layer encapsulation format types, based on a cost or bandwidth associated with a network, or associated with a link of the network, connected between the first device and the second device,
wherein each of the multiple different session layer encapsulation format types comprises session layer encapsulation having different quantities of data overhead, and
wherein the multiple different session layer encapsulation format types comprise a first encapsulation format type having a first quantity of data overhead and a second encapsulation format type having a second quantity of data overhead, wherein the first quantity of data overhead is greater than the second quantity of data overhead,
create an entry for the session in a SPD, wherein the entry includes the session identity, the SPI, and the selected session layer encapsulation format type.
17. The device of claim 16, wherein the processing unit is further configured to:
exchange, via the one or more communication interfaces, the SPI with the second application.
18. The device of claim 16, wherein the processing unit is further configured to:
negotiate, between the first application and the second application via the one or more communication interfaces, a ciphersuite for encrypting data session layer data between the first application and the second application.
19. The device of claim 18, wherein the processing unit is further configured to:
obtain, at the first application based on the negotiated ciphersuite, an encryption key for the session.
20. The device of claim 16, wherein the processing unit is further configured to:
obtain, at the first application, an encryption key for the session.
21. The method of claim 16, wherein the processing unit is further configured to:
negotiate, between the first application and the second application, a ciphersuite for encrypting data session layer data between the first application and the second application;
obtain, at the first application based on the negotiated ciphersuite, an encryption key for the session,
wherein the entry for the session in the SPD further includes the ciphersuite and the encryption key.
22. The method of claim 10, wherein the multiple different session layer encapsulation format types further comprise a third encapsulation format type having a third quantity of data overhead, where the third quantity of data overhead is greater than the first quantity of data overhead and the second quantity of data overhead.
23. The method of claim 22, wherein the multiple different session layer encapsulation format types further comprise a fourth encapsulation format type having a fourth quantity of data overhead, where the fourth quantity of data overhead is greater than the first quantity of data overhead, the second quantity of data overhead, and the third quantity of data overhead.
24. The device of claim 16, wherein the multiple different session layer encapsulation format types further comprise a third encapsulation format type having a third quantity of data overhead, where the third quantity of data overhead is greater than the first quantity of data overhead and the second quantity of data overhead.
25. The device of claim 24, wherein the multiple different session layer encapsulation format types further comprise a fourth encapsulation format type having a fourth quantity of data overhead, where the fourth quantity of data overhead is greater than the first quantity of data overhead, the second quantity of data overhead, and the third quantity of data overhead.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An optical device, comprising:
a substrate of optical material having a first surface and an opposing second surface;
a first diffractive element disposed on the substrate for receiving an input optical beam defined by a wave-vector k and containing periodic lines with a period d;
a second diffractive element disposed on the substrate in relationship with the first diffractive element and containing further periodic lines with a period d, wherein an angle between said periodic lines and said further periodic lines is 2\u03c1; and
an intermediate diffractive element disposed on said substrate adjacent to the first and the second diffractive elements and containing still further periodic lines with the period d2 cos \u03c1, wherein \u03c1 is an angle between said periodic lines and the still further periodic lines and said angle \u03c1 is not equal to 45\xb0, wherein
at least part of the input optical beam is diffracted in the first diffractive element for providing a diffracted optical component to the intermediate diffractive element substantially within the first and second surfaces, and
at least part of the diffracted optical component in the intermediate diffractive element is coupled to the second diffractive element substantially between the first and second surfaces so as to allow at least part of the coupled diffracted optical component to exit the substrate by diffraction in the second diffractive element for providing an output optical beam defined by a further wave-vector k1 having exactly the same direction as the wave-vector k of said input optical beam.
2. The optical device of claim 1, wherein said optical device is for extending of an exit pupil of said input optical beam by providing said output optical beam.
3. The optical device of claim 1, wherein said diffracted optical component is incident and subsequently diffracted to a first diffraction order on the intermediate diffractive element an uneven number of times before providing said at least part of the diffracted light component to said second diffractive element.
4. The optical device of claim 1, wherein said intermediate diffractive element supports only reflective zero and first order diffraction modes, or an index of refraction of said substrate is n>\u03bbd, wherein \u03bb is a wavelength of the input optical beam.
5. The optical device of claim 1, wherein a second or higher order diffraction modes are unsupported by said intermediate diffractive element, which is enforced by a condition expressed as
1
+
8
\ue89e
\ue89e
cos
2
\ue89e
\u03c1
>
nd
\u03bb
,
wherein n is an index of refraction of said substrate, \u03bb is a wavelength of the input optical beam.
6. The optical device of claim 5, wherein 0<\u03c1<70\xb0.
7. The optical device of claim 1, wherein a predetermined condition is maintained, said condition is that transmission diffraction modes are unsupported for said intermediate diffractive element, which is enforced by a condition expressed as \u03bbd>1, wherein \u03bb is a wavelength of the input optical beam.
8. The optical device of claim 1, wherein said first diffractive element, said second diffractive element or said intermediate diffractive element is disposed on said first surface or on said second surface.
9. A method, comprising:
receiving an input optical beam defined by a wave-vector k at a first diffractive element containing periodic lines with a period d and disposed on a substrate of optical material having a first surface and an opposing second surface;
diffracting at least part of the input optical beam in the first diffractive element for providing a diffracted optical component to an intermediate diffractive element substantially within the first and second surfaces;
further diffracting said diffracted optical component by said intermediate diffractive element; and
coupling at least part of said further diffracted said diffracted optical component in the intermediate diffractive element to a second diffractive element substantially between the first and second surfaces so as to allow at least part of the coupled diffracted optical component to exit the substrate by diffraction in the second diffractive element for providing an output optical beam defined by a further wave-vector k1 having exactly the same direction as the wave-vector k of said input optical beam for extending of the exit pupil of an input optical beam, wherein
said second diffractive element is disposed on said substrate in relationship with the first diffractive element and contains further periodic lines with a period d and wherein an angle between said periodic lines and said further periodic lines is 2\u03c1 and
said intermediate diffractive element is disposed adjacent to the first and the second diffractive elements and contains still further periodic lines with the period d2 cos \u03c1, wherein \u03c1 is an angle between said periodic lines and the still further periodic lines and said angle \u03c1 is not equal to 45\xb0.
10. The method of claim 9, wherein said diffracted optical component is incident and subsequently diffracted to a first diffraction order on the intermediate diffractive element an uneven number of times before said at least part of the diffracted light component is provided to said second diffractive element.
11. The method of claim 9, wherein said intermediate diffractive element is configured to support only zero and first order reflective diffraction modes, or an index of refraction of said substrate is n>\u03bbd, wherein \u03bb is a wavelength of the input optical beam.
12. The method of claim 9, wherein the intermediate diffractive element is configured not to support a second or higher order diffraction modes, which is enforced by a condition expressed as
1
+
8
\ue89e
\ue89e
cos
2
\ue89e
\u03c1
>
nd
\u03bb
,
wherein n is an index of refraction of said substrate, \u03bb is a wavelength of the input optical beam.
13. The method of claim 12, wherein 0<\u03c1<70\xb0.
14. The method of claim 9, wherein the intermediate diffractive element is configured not to support transmission diffraction modes, which is enforced by a condition expressed as \u03bbd>1, wherein \u03bb is a wavelength of the input optical beam.
15. The method of claim 9, wherein said first diffractive element, said second diffractive element or said intermediate diffractive element is disposed on said first surface or on said second surface.
16. An electronic device, comprising:
a data processing unit;
an optical engine operatively connected to the data processing unit for receiving image data from the data processing unit;
a display device operatively connected to the optical engine for forming an image based on the image data; and
an exit pupil expander comprising:
a substrate of optical material having a first surface and an opposing second surface;
a first diffractive element disposed on the substrate for receiving an input optical beam defined by a wave-vector k and containing periodic lines with a period d;
a second diffractive element disposed on the substrate in relationship with the first diffractive element and containing further periodic lines with a period d, wherein an angle between said periodic lines and said further periodic lines is 2\u03c1; and
an intermediate diffractive element disposed on said substrate adjacent to the first and the second diffractive elements and containing still further periodic lines with the period d2 cos \u03c1, wherein \u03c1 is an angle between said periodic lines and the still further periodic lines and said angle \u03c1 is not equal to 45\xb0, wherein
at least part of the input optical beam is diffracted in the first diffractive element for providing a diffracted optical component to the intermediate diffractive element substantially within the first and second surfaces, and
at least part of the diffracted optical component in the intermediate diffractive element is coupled to the second diffractive element substantially between the first and second surfaces so as to allow at least part of the coupled diffracted optical component to exit the substrate by diffraction in the second diffractive element for providing an output optical beam defined by a further wave-vector k1 having exactly the same direction as the wave-vector k of said input optical beam.
17. The electronic device of claim 16, wherein said intermediate diffractive element is configured to support only reflective zero and first order reflective diffraction modes, or an index of refraction of said substrate is n>\u03bbd, wherein \u03bb is a wavelength of the input optical beam.
18. The electronic device of claim 16, wherein the intermediate diffractive element is configured not to support a second or higher order diffraction modes, which is enforced by a condition expressed as
1
+
8
\ue89e
\ue89e
cos
2
\ue89e
\u03c1
>
nd
\u03bb
,
wherein n is an index of refraction of said substrate, \u03bb is a wavelength of the input optical beam.
19. The electronic device of claim 18, wherein 0<\u03c1<70\xb0.
20. The electronic device of claim 16, wherein the intermediate diffractive element is configured not to support transmission diffraction modes, which is enforced by a condition expressed as \u03bbd>1, wherein \u03bb is a wavelength of the input optical beam.
21. The electronic device of claim 16, wherein said electronic device is a digital camera, a computer game device, a wireless device, a portable device or a mobile terminal.
22. The electronic device of claim 16, further comprising a communications unit for receiving signals containing information indicative of the image data, wherein the data processing unit is operatively connected to the communications unit for receiving the information.