Patent ID: 7773274

Claim:
A method to store information in a holographic data storage medium, comprising the steps of: supplying a holographic data storage medium comprising an encoded focusing hologram and one or more encoded data holograms; providing a first holographic data storage system comprising a light source, an optical detector and a moveable imaging lens; disposing said holographic data storage medium in said holographic data storage system such that said moveable imaging lens is disposed at an (i)th position between said holographic data storage medium and said optical detector, wherein (i) is initially set to 1; establishing a threshold focusing metric; illuminating said encoded focusing hologram with a reference beam to generate an (i)th reconstructed focusing image; projecting said (i)th reconstructed focusing image through said moveable imaging lens, and onto said optical detector; providing a reference focusing image; calculating an (i)th measured focusing metric by comparing said (i)th reconstructed focusing image with said reference focusing image, wherein said (i)th focusing metric comprises a bit error rate; determining if said (i)th measured focusing metric is greater than or equal to said threshold focusing metric; operative if said (i)th measured focusing metric is greater than or equal to said threshold focusing metric, decoding said one or more encoded data holograms.