Abstract: A device for viewing a projected image includes an input coupling grating operable to receive light related to the projected image from a light source and an expansion grating having a first grating structure characterized by a first set of grating parameters varying in one or more dimensions. The expansion grating structure is operable to receive light from the input coupling grating and to multiply the light related to the projected image. The device also includes an output coupling grating having a second grating structure characterized by a second set of grating parameters and operable to output the multiplied light in a predetermined direction.

Abstract: A server/overlay network architecture and related method prevent (i.e., minimize the likelihood of) overloads from many network clients all trying to upload data files to a common destination server on the network at about the same time. Before a client transfers its (his or her) data file to the common network destination, a unique identifier (generally much smaller than the data itself) for the data of that client is generated. The unique identifier, such as a one-way hash function, is transmitted to an authenticator trusted by the common destination. The authenticator time-stamps (i.e., stores time and date) the unique identifier, digitally signs a message incorporating the unique identifier and the time-stamp and sends the message to the client who sent the unique identifier. The client then sends the data file with its time stamp to one of a plurality of upload proxy servers. The proxy server sends a message to the common destination telling it to pick up the data file when ready.

Abstract: A server/overlay network architecture and related method prevent (i.e., minimize the likelihood of) overloads from many network clients all trying to upload data files to a common destination server on the network at about the same time. Before a client transfers its (his or her) data file to the common network destination, a unique identifier (generally much smaller than the data itself) for the data of that client is generated. The unique identifier, such as a one-way hash function, is transmitted to an authenticator trusted by the common destination. The authenticator time-stamps (i.e., stores time and date) the unique identifier, digitally signs a message incorporating the unique identifier and the time-stamp and sends the message to the client who sent the unique identifier. The client then sends the data file with its time stamp to one of a plurality of upload proxy servers. The proxy server sends a message to the common destination telling it to pick up the data file when ready.