Post-curing of holographic media
The present invention relates to embodiments of a process for subjecting a holographic storage medium to illuminative treatment to: ( 1 ) enhance or optimize recording of holographic data; ( 2 ) enhance or optimize reading of recorded holographic data; and/or ( 3 ) erase recorded holographic data. The present invention also relates to embodiments of a system comprising: (a) an illuminative treatment beam; (b) means for reducing the coherence of the beam and (c) means for transmitting the reduced coherence beam to cause illuminative treatment of: ( 1 ) an unrecorded portion of a holographic storage medium to provide pre-cured portions having increased ability to stably record holographic data; ( 2 ) a recorded portion of a holographic storage medium to provide a post-cured portion having reduced residual sensitivity; and/or ( 3 ) a recorded portion of a holographic storage medium having holographic data to provide an erased portion wherein at least some of the recorded holographic data is erased.
1 . A process comprising the following steps of:
(a) providing a holographic storage medium having a recorded portion; and
(b) subjecting the recorded portion to illuminative post-curing with a curing beam having reduced coherence and a substantially uniform intensity distribution to provide a post-cured portion having reduced residual sensitivity.
2 . The process of claim 1 , wherein step (b) is carried out with a curing beam having the same wavelength of light as that of recording light used to record holographic data to the recorded portion.
3 . The process of claim 1 , wherein step (b) is carried out with a curing beam having a different wavelength of light from that of recording light used to record holographic data to the recorded portion.
4 . The process of claim 3 , wherein step (b) is carried out with a curing beam having a wavelength providing maximum absorption by photoactive materials present in the holographic medium.
5 . The process of claim 1 , wherein step (b) is carried out for a predetermined period.
6 . The process of claim 1 , wherein step (b) is carried out by multi-pass curing of the recorded portion.
7 . The process of claim 1 , wherein step (b) is carried out so as to post-cure only a selected recorded portion of the holographic medium.
8 . The process of claim 7 , wherein step (b) is carried out by moving the holographic medium relative to the curing beam while simultaneously and continuously illuminating the selected recorded portion with the curing beam.
9 . The process of claim 8 , wherein movement of the holographic medium carried out in step (b) comprises a substantially linear translation of the holographic medium.
10 . The process of claim 8 , wherein movement of the holographic medium carried out in step (b) alternates between: (1) a substantially linear translation of the holographic medium in a first direction; and (2) a substantially linear translation of the holographic medium in a second direction which is transverse to the first direction.
11 . The process of claim 10 , wherein the first and second directions of the holographic medium are substantially orthogonal.
12 . The process of claim 9 , wherein movement of the holographic medium carried out in step (b) comprises a continuous, unidirectional rotation of the holographic medium.
13 . The process of claim 8 , wherein the holographic medium motion carried out in step (b) alternates between: (1) continuous, unidirectional rotation of the holographic medium; and (2) a substantially linear translation of the holographic medium.
14 . The process of claim 8 , wherein the holographic medium motion carried out in step (b) is carried out by simultaneously performing (1) continuous, unidirectional rotation of the holographic medium; and (2) a substantially linear translation of the holographic medium
15 . The process of claim 1 , wherein step (a) comprises providing a holographic storage medium comprising photoactive luminescent materials and wherein the degree of post-curing during step (b) is determined by monitoring the luminescence of the luminescent materials.
16 . The process of claim 15 , wherein step (a) comprises providing a holographic storage medium comprising photoactive fluorescent materials.
17 . The process of claim 15 , wherein step (a) comprises providing a holographic storage medium comprising photoactive phosphorescent materials.
18 . The process of claim 1 , wherein the degree of post-curing during step (b) is determined by monitoring the transmittance of the curing beam.
19 . The process of claim 1 , wherein step (a) is carried out by providing a holographic medium comprising residual free radical photoinitiator and a polymerizable component comprising residual photoactive polymerizable material that is caused to be polymerized by a free radical photoinitiator.
20 . The process of claim 1 , wherein step (a) is carried out by providing a holographic medium having a recorded portion and a pre-cured unrecorded portion, and wherein step (b) is carried out on the recorded portion and the pre-cured unrecorded portion.
21 . The process of claim 1 , wherein step (b) is carried out with a curing beam having a wavelength providing maximum absorption by photoactive materials present in the holographic medium
22 . The process of claim 1 , wherein step (b) is carried out while concurrently carrying out the following additional step of recording holographic data in a different portion of the holographic medium.
23 . A system comprising:
a curing beam;
means for reducing coherence of the curing beam to provide a curing beam having reduced coherence; and
means for transmitting the reduced coherence curing beam with a substantially uniform intensity distribution to cause illuminative post-curing of a recorded portion of a holographic storage medium to provide a post-cured portion having reduced residual sensitivity.
24 . The system of claim 23 , which is part of a holographic data storage system.
25 . The system of claim 24 , wherein the curing beam is generated by a laser from the holographic data storage system.
26 . The system of claim 25 , wherein the laser is adjustable to provide a first wavelength of light for recording holographic data, and a second different wavelength of light for generating the curing beam.
27 . The system of claim 23 , which further comprises a separate non-recording light source to generate the curing beam.
28 . The system of claim 27 , wherein the separate non-recording light source is a laser.
29 . The system of claim 27 , wherein the separate non-recording light source is a light emitting diode.
30 . The system of claim 27 , which is separate from a holographic data storage system.
31 . The system of claim 27 , which is part of a holographic data storage system.
32 . The system of claim 23 , wherein the coherence reducing means comprises a diffuser.
33 . The system of claim 32 , wherein the coherence reducing means comprises means for imparting motion to the diffuser.
34 . The system of claim 23 , wherein the coherence reducing means comprises integrating rods.
35 . The system of claim 23 , wherein the curing beam is generated by a laser and wherein the coherence reducing means comprises means for modulating the electrical current to the laser generating the curing beam.
36 . The system of claim 23 , wherein the transmitting means comprises means for shaping the curing beam so as to cause illuminative post-curing of a selected recorded portion of the holographic medium.
37 . The system of claim 36 , wherein the shaping means shapes the curing beam to a predetermined shape.
38 . The system of claim 37 , wherein the shaping means comprises a combination of a lenslet array and a transform lens.
39 . The system of claim 23 , wherein the transmitting means comprises at the least a portion of an optical path of a holographic data storage system.
40 . The system of claim 39 , wherein the optical path comprises a reference beam optical path.
41 . The system of claim 39 , wherein the optical path comprises the data beam optical path.
42 . The system of claim 23 , wherein the transmitting means includes means for reflecting at least a portion of unabsorbed curing beam through the holographic medium to cause multi-pass pre-curing of the uncured portion.
43 . The system of claim 42 , wherein the curing beam is transmitted to one side of the holographic medium and wherein the reflecting means is positioned on the opposite of the holographic medium.
44 . The system of claim 43 , wherein the reflecting means comprises a mirror.
45 . The system of claim 44 , wherein the reflecting means comprises a parabolic mirror or the combination of one or more lenses and a mirror.
46 . A process comprising the following steps:
(a) providing a holographic storage medium having an uncured portion;
(b) subjecting the uncured portion to illuminative pre-curing with a curing beam having reduced coherence and a substantially uniform intensity distribution to provide a pre-cured portion having increased ability to stably record holographic data;
(c) recording holographic data in the pre-cured portion to provide a recorded portion having holographic data; and
(d) subjecting the recorded portion to illuminative post-curing with a curing beam having reduced coherence and a substantially uniform intensity distribution to provide a post-cured recorded portion having reduced residual sensitivity.
47 . The process of claim 46 , wherein steps (b) and (d) are each carried out with a pre-curing beam and post-curing beam having a wavelength providing maximum absorption by photoactive materials present in the holographic medium.
48 . The process of claim 46 , wherein steps (b) and (d) are each carried out for a predetermined period.
49 . The process of claim 46 , wherein step (a) is carried out by providing a holographic medium comprising a free radical photoinitiator and a polymerizable component comprising a photoactive polymerizable material that is caused to be polymerized by a free radical photoinitiator.
50 . The process of claim 46 , wherein steps (b) and (d) are carried out by multi-pass curing.
51 . The process of claim 46 , wherein step (a) comprises providing a holographic storage medium comprising photoactive luminescent materials and wherein the degree of pre-curing and post-curing during each of steps (b) and (d) is determined by monitoring the luminescence of the luminescent materials.
52 . The process of claim 46 , wherein the degree of post-curing during step (b) is determined by monitoring the transmittance of the curing beam.
53 . A system comprising:
a curing beam;
means for reducing coherence of the curing beam to provide a curing beam having reduced coherence; and
means for transmitting the reduced coherence curing beam with a substantially uniform intensity distribution to cause, in sequence: (1) illuminative pre-curing of an uncured unrecorded portion of a holographic storage medium to provide a pre-cured portion having increased ability to stably record holographic data; and (2) illuminative post-curing of the pre-cured portion having recorded holographic data to provide a post-cured recorded portion having reduced residual sensitivity.
54 . The system of claim 53 , which is part of a holographic data storage system.
54 . The system of claim 54 , wherein the curing beam is generated by a laser from the holographic data storage system.
56 . The system of claim 55 , wherein the laser is adjustable to provide a first wavelength of light for recording holographic data, and a second different wavelength of light for generating the curing beam.
57 . The system of claim 53 , which further comprises a separate non-recording light source to generate the curing beam.
58 . The system of claim 57 , wherein the separate non-recording light source is a laser.
59 . The system of claim 57 , wherein the separate non-recording light source is a light emitting diode.
60 . The system of claim 53 , wherein the coherence reducing means comprises a diffuser.
61 . The system of claim 60 , wherein the coherence reducing means comprises means for imparting motion to the diffuser.
63 . The system of claim 53 , wherein the curing beam is generated by a laser and wherein the coherence reducing means comprises means for modulating the electrical current to the laser generating the curing beam.
64 . The system of claim 53 , wherein the transmitting means comprises at the least a portion of an optical path of a holographic data storage system.
65 . The system of claim 64 , wherein the optical path comprises a reference beam optical path.
66 . The system of claim 64 , wherein the optical path comprises the data beam optical path.
67 . The system of claim 53 , wherein the transmitting means includes means for reflecting at least a portion of unabsorbed curing beam through the holographic medium to cause multi-pass pre-curing or post-curing.
68 . The system of claim 67 , wherein the curing beam is transmitted to one side of the holographic medium and wherein the reflecting means is positioned on the opposite of the holographic medium.
69 . The system of claim 68 , wherein the reflecting means comprises a mirror.
70 . The system of claim 69 , wherein the reflecting means comprises a parabolic mirror or the combination of one or more lenses and a mirror.