Holographic elements for an optical recording system

Claim 2

Apparatus as claimed in claim 1, wherein said volume holographic optical element (103) is adapted to perform one or more of the following functions, namely generating servo error signals, generating servo drawing signals, generating a focus error signal, generating a tracking error signal, collimation, focussing, beam shaping, wavefront correction, or combining at least two beams; and said apparatus further comprises means (102) for rotating a moving data storage media (45) in said raypath so as to derive digital data therefrom.

Claim 3

Apparatus as recited in claim 1 or 2, wherein said light source (100) is a laser.

Claim 4

Apparatus as recited in claim 2, wherein said light source (100) is a laser diode.

Claim 5

Apparatus as recited in any preceding claim, wherein said holographic optical element comprises a first holographic optical element (103) and a second holographic optical element (104), said first holographic optical element being a collimation element and said second holographic optical element being a focusing element.

Claim 6

Apparatus as recited in any preceding claim, further comprising a light detection element (102) for receiving light reflected from an optical data storage disc (45).

Claim 7

Apparatus as recited in claim 6, wherein said light source (100) and said light detection element (102) are in a common housing (106).

Claim 8

Apparatus as recited in claim 7, wherein said light source (100) is a laser diode and said light detection element (102) is one or more photodiodes.

Claim 9

Apparatus as recited in any preceding claim, wherein said holographic optical element (103) collimates and focuses light from said light source (100) on an optical data storage media (102).

Claim 10

Apparatus as recited in any preceding claim, wherein said light source comprises first (100a) and second (100b) light sources.

Claim 11

Apparatus as recited in any preceding claim, wherein said light source is an uncollimated light source, said apparatus comprising a collimation lens (114) for collimating light from said light source, said holographic optical element (103) focussing the light on an optical data storage medium.

Claim 12

Apparatus as recited in claim 11, wherein said holographic optical element is between said collimation lens and said optical data storage media, or said collimation lens (114) is between said holographic optical element (103) and said optical data storage media.

Claim 13

Apparatus as recited in any preceding claim, wherein said light source is a write wavelength light source, said write wavelength causing said optical media to expand in response thereto to form an optically detectable data bump.

Claim 14

An optical digital data system comprising: a) first (100a) and second (100b) divergent light sources; b) a volume holographic optical element (HOE) (103), said volume HOE being positioned in a light path between said first and second light sources, and an optical data storage media (45), and being adapted to: i) combine beams from said first and second divergent light sources; and ii) collimate light from said first and second light sources.

Claim 15

Apparatus as recited in any one of claims 1 to 14, wherein said light source produces light having a gaussian intensity distribution.

Claim 16

Apparatus as recited in claim 15, wherein said holographic optical element shapes light from said light source by making said gaussian intensity profile more uniform.

Claim 17

Apparatus as recited in any preceding claim, wherein said holographic optical element splits light from said optical data storage media into two or more focused beams.

Claim 18

Apparatus as recited in claim 8 and any preceding claim, wherein said photo diodes are separated from one another along a common axis.

Claim 19

Apparatus as recited in claim 8 and any preceding claim, wherein said one or more photo diodes are comprised of two or more elements (12, 14), each of said elements generating a signal.

Claim 20

Apparatus as recited in claim 19, wherein said elements are an inner element (12) and an outer element (14), said inner element being circular in shape and said outer element surrounding said inner element.

Claim 21

Method of making an inverse gaussian filter comprising the steps of splitting a light beam into a first secondary light beam (36) and a second secondary light beam (38), each secondary light beam having a gaussian intensity distribution, directing said first secondary light beam into an undeveloped volume holographic optical element (40), directing said second secondary light beam into shaping optics (42), said shaping optics causing the intensity profile of the second secondary light beam to become substantially more uniform, then directing said second secondary light beam onto said undeveloped holographic optical element (40), and developing said undeveloped holographic optical element.