Optical compensation of hologram distortion avoiding interpage crosstalk on reconstructed image in angle-multiplexed holograms

Muroi, Tetsuhiko; Kinoshita, Nobuhiro; Ishii, Norihiko; Kamijo, Koji; Kikuchi, Hiroshi; Kawata, Yoshimasa; Shimidzu, Naoki

doi:10.1364/ao.50.005700

Cited by 4 publications

(6 citation statements)

References 6 publications

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“…In our previous studies, we showed that adaptive optics with a genetic algorithm can optimize the wavefront of the reference beam to compensate for hologram distortion and improve the bER of the reproduced data [5,6]. With this type of adaptive optics, the evaluation value expressed by…”

Section: -5mentioning

confidence: 99%

“…is used to evaluate the reproduced data quality [6]. Here, µ is the mean of the brightness of the bits and c is the coefficient of variation, which is the standard deviation σ normalized to the mean brightness and expressed by σ/µ.…”

Section: -5mentioning

confidence: 99%

“…The bERs of the reproduced data were more than 1 ×10 −2 on all data pages. In angle multiplexed holograms, since the difference of hologram distortion between several neighboring data pages is not very big, the wavefront to compensate for hologram distortion on any page can compensate for hologram distortion on several neighboring data pages [6]. Therefore, we were able to control the defocus component to compensate for hologram distortion on page number 39 (the 40th data page), which is directly in the middle of the 80 data pages in angle multiplexed holograms.…”

Section: Reduction Of Ber In Angle Multiplexed Hologramsmentioning

confidence: 99%

“…As a result, the signal to noise ratio (SNR) of the reproduced data decreases and the bit error rate (bER) increases. Potential methods to optically compen-sate for such hologram distortions include adjusting the incident angle, controlling the wavelength, and optimizing the wavefront of the reference beam while reproducing [2]- [6]. However, methods that combine adjusting the incident angle with controlling the wavelength of the reference beam cannot sufficiently compensate for hologram distortion when a high NA object lens is used to record data with high density.…”

Section: Introductionmentioning

confidence: 99%

“…However, methods that combine adjusting the incident angle with controlling the wavelength of the reference beam cannot sufficiently compensate for hologram distortion when a high NA object lens is used to record data with high density. In contrast, a method that combines adjusting the incident angle with optimizing the wavefront of the reference beam can compensate for distortion and improve the bER of the reproduced data even if a high NA object lens is used [5,6]. However, the problem with this latter approach is that it is difficult to individually obtain a satisfactory wavefront to compensate for complex hologram distortion for each data page while real-time data reproduction is performed in multiplexed holograms.…”

Section: Introductionmentioning

confidence: 99%

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Compensation of hologram distortion by controlling defocus component in reference beam wavefront for angle multiplexed holograms

Muroi

Kinoshita

Ishii

et al. 2013

J. Eur. Opt. Soc.-Rapid Publ.

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Holographic memory has the potential to function as a recording system with a large capacity and high data-transfer-rate. Photopolymer materials are typically used as a write-once recording medium. When holograms are recorded on this medium, they can distort due to shrinkage or expansion of the materials, which degrades the reconstructed image and causes a higher bit error rate (bER) of the reproduced data. We propose optically compensating for hologram distortion by controlling aberration components in the reference beam wavefront while reproducing data, thereby improving the reproduced data quality. First, we investigated the relation between each aberration component of the reference beam and the signal to noise ratio (SNR) of the reproduced data using numerical simulation and found that horizontal tilt and the defocus component affect the SNR. Next, we experimentally evaluated the reproduced data by controlling the defocus component in the reference beam and found that the bER of the reproduced data could be decreased by controlling the defocus center with respect to the hologram position and phase modulation depth of the defocus component. Then, we investigated a practical control method of the defocus component using an evaluation value similar to the definition of the SNR for actual data reproduction from holograms. Using a defocus controlled wavefront enabled us to decrease the bER from 3.54 × 10 −3 with a plane wave to 3.14 × 10 −4 . We also investigated how to reduce the bERs of reproduced data in angle multiplexed holograms. By using a defocus controlled wavefront to compensate for hologram distortion on the 40th data page in 80-page angle multiplexed holograms, the bERs of all pages could be decreased to less than 1 ×10 −3 . We showed that controlling the defocus component is an effective way to compensate for hologram distortion and to decrease the bER of reproduced data in holographic memory.

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Section: -5mentioning

confidence: 99%

Section: -5mentioning

confidence: 99%

Section: Reduction Of Ber In Angle Multiplexed Hologramsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Compensation of hologram distortion by controlling defocus component in reference beam wavefront for angle multiplexed holograms

Muroi

Kinoshita

Ishii

et al. 2013

J. Eur. Opt. Soc.-Rapid Publ.

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Optical compensation for hologram distortion using wavefront interpolation in angle-multiplexed holograms

Muroi

Kinoshita

Ishii

et al. 2014

Journal of Modern Optics

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Angular Spacing Control for Segmented Data Pages in Angle-Multiplexed Holographic Memory

Kinoshita¹,

Muroi²,

Ishii³

et al. 2011

Jpn. J. Appl. Phys.

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To improve the recording density of angle-multiplexed holographic memory, it is effective to increase the numerical aperture of the lens and to shorten the wavelength of the laser source as well as to increase the multiplexing number. The angular selectivity of a hologram, which determines the multiplexing number, is dependent on the incident angle of not only the reference beam but also the signal beam to the holographic recording medium. The actual signal beam, which is a convergent or divergent beam, is regarded as the sum of plane waves that have different propagation directions, angular selectivities, and optimal angular spacings. In this paper, focusing on the differences in the optimal angular spacing, we proposed a method to control the angular spacing for each segmented data page. We investigated the angular selectivity of a hologram and crosstalk for segmented data pages using numerical simulation. The experimental results showed a practical bit-error rate on the order of 10-3.

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Optical compensation of hologram distortion avoiding interpage crosstalk on reconstructed image in angle-multiplexed holograms

Cited by 4 publications

References 6 publications

Compensation of hologram distortion by controlling defocus component in reference beam wavefront for angle multiplexed holograms

Compensation of hologram distortion by controlling defocus component in reference beam wavefront for angle multiplexed holograms

Optical compensation for hologram distortion using wavefront interpolation in angle-multiplexed holograms

Angular Spacing Control for Segmented Data Pages in Angle-Multiplexed Holographic Memory

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