記錄於倒數空間高繞射效率之全像儲存系統;A Holographic Data Storage System Recorded in Reciprocal Space with High Diffractive Efficiency

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/92412

Title:	記錄於倒數空間高繞射效率之全像儲存系統;A Holographic Data Storage System Recorded in Reciprocal Space with High Diffractive Efficiency
Authors:	陳奕墉;Chen, Yi-Yung
Contributors:	光電科學與工程學系
Keywords:	全像術;全像儲存
Date:	2023-08-15
Issue Date:	2024-09-19 15:50:44 (UTC+8)
Publisher:	國立中央大學
Abstract:	在傳統的全像儲存系統中，我們可以利用全像片感光材料層的厚度，在同一塊區域中對不同角度資訊的多工記錄。而有鑑於目前的全像儲存多工技術中，存在著多工張數對於繞射效率的影響，且其繞射效率會隨著多工張數增加而下降至多工張數的平方倍，另一方面，繞射效率降低會降低儲存系統的讀取速度及儲存容量。因此，我們提出了「N倍繞射效率之體積全像多工技術」，改善了上述提到繞射效率降低為多工張數平方倍的問題，但是實驗的讀取影像資訊有著資訊不均勻的狀況。本論文提出了記錄倒數空間中的資訊，再經過透鏡將資訊傅式轉換為原本設計的訊號，以改善讀取訊號的均勻度，並增加記錄資訊頁數；此全像儲存系統將資訊多工記錄在同一塊記錄區域中，讀取到的訊號為每道讀取光個別讀取的訊號疊加後的干涉結果，透過全像底片的位移，讀取位置對應到讀取光的波前改變，資訊的相位亦受到改變，因此，我們藉由設計訊號疊加的相位在位移讀取時產生建設性干涉及破壞性干涉的結果，可以改變不同位移量得到訊號亮暗的變化，並且透過記錄倒數空間的資訊得到較高均勻度的讀取資訊。 ;In traditional holographic storage systems, we can utilize the thickness of the photosensitive material layer in holographic plates to achieve multiplex recording of information from different angles within the same area. However, current holographic storage multiplexing techniques suffer from a decrease in diffraction efficiency as the number of multiplexed holograms increases. The diffraction efficiency tends to decrease by the square of the multiplexing factor, which negatively impacts readout speed and capacity. To address this issue, we propose the " N Times Enhancement of Diffraction Efficiency of Volume Holographic Multiplexing Technology," which improves the problem of diffraction efficiency decreasing by the square of the multiplexing factor. However, experiments have shown uneven distribution of information in the readout images. In this paper, we introduce the recording of information in reciprocal space and subsequently transform the information through a lens using Fourier transformation. This process improves the uniformity of the readout signal and increases the number of recorded information pages. In this holographic storage system, multiple sets of information are multiplexed and recorded in the same recording area. The readout signal is obtained by the interference of individually retrieved signals from each reading beam. By introducing a shift in the holographic plate, the readout position corresponds to a change in the wavefront of the reading beam, resulting in a phase change in the recorded information. Therefore, we design the phase of the superimposed signals to produce constructive and destructive interference during the shift readout process, allowing for variations in signal intensity corresponding to different shift distances. Additionally, utilizing the information in reciprocal space enables higher uniformity in the readout information.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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