Study of the Integrated Collinear Holographic Storage System

本研究探討一種應用積體化光學模組之技術於同軸全像儲存系統之新式設計架構，此光學架構具有讀寫全像多功能碟片(holographic versatiledisk, HVD)與反相讀寫CD 及DVD 碟片的功能。光學系統中包含有一全像光學元件(holographic optical element)用以分離光束與產生伺服訊號、一具有中心資料區與外環參考區用以調變入射光束的穿透型空間光調製器(spatial light modulator, SLM)、以及一搭配此SLM 之新式外環狀偏光片。此外，系統中並包含有兩分別用以讀寫HVD 之綠或藍光雷射與用以讀寫CD/DVD 之紅光雷射，另有一偵測綠或藍光讀取光束之影像感測器與一偵測紅光讀取光束之光偵測器。本研究規劃為三年期之計畫，第一年度主要著重於完成積體化同軸全像儲存系統之設計與分析，第二年進行系統之製作、組裝與驗證，第三年則對此系統之伺服控制與反向相容特性加以探討。This study investigates the configuration of a novel design that applies thetechnology of integrated optical unit to the collinear holographic storagesystem. It has the functions of recording and retrieving data on the holographicversatile disk (HVD) and backward compatible to the CD and DVD. Thissystem comprises a holographic optical element for splitting light andgenerating servo signal, a transmissive spatial light modulator (SLM) withcentral data part and outer-ring reference part for modulating the incident beam,and a novel outer-ring polarizer accompanied with the SLM. Besides, there aretwo lasers, one with green or blue wavelength for the HVD and the other withred wavelength for the CD/DVD, included in the system. Also, one imagesensor and one photo-detector are used for detecting the green and red readoutbeams, respectively.This project is a plan with the period of three years. The first year』s goal isto fulfill the design and analysis of the integrated collinear holographic storagesystem. Further fabrication, assembly, and verification of this system are thetargets of the second year. Finally, we will proceed to the servo control andbackward compatibility for the system

Study of Optical Compensator with Multiple Modes

本研究探討具有可切換聚焦功能之多模式光學補償片架構。利用調變液晶折射率，施加電壓於環狀電極上，以及採用雙層液晶來解決極化選擇性，我們提出兩種新式多聚焦模式之光學補償片設計架構。第一種架構將電極作數個圓形環狀分區，並施以高低不同之電壓驅動，以使每一區內液晶產生不同之光程調變量，而等效於一梯度折射率型(graded-index)折射透鏡。並可根據每一環狀電極之電壓極性而切換成正或負透鏡之不同模態。第二種架構則是採用菲涅耳(Fresnel)區帶環之模式，設計菲涅耳電極與互補電極，並結合高分子穩固型液晶(polymer stabilized liquid crystal, PSLC)技術以得到多種模態之特性。兩種架構可應用於具有自動對焦之相機的光學模組設計，用以補償鏡頭焦距，產生多種不同之焦點位置；亦可應用於需要多種聚焦特性之光學器件上。由初步之光學模擬與實驗已確認本研究架構之可行性，未來計畫執行期間將進一步分析液晶之光學特性以及實際完成元件之製作，並搭配鏡頭模組作成像系統之驗證。本研究規劃為三年期之計畫，第一年度主要著重於文獻與理論之探討，以及第一種架構之實作驗證；第二年則建立於第一年之成果，以雙層電極作補償片之改善；第三年則進行第二種架構之實作驗證，並整合光學鏡組作成像系統之特性驗證。This study investigates the configuration of optical compensators that havethe feature of switching focusing characteristics with multiple modes. Bymodulating the index of refraction of liquid crystals (LCs), applying voltageson the ring-type electrodes, and adopting dual LC layers to solve thepolarization selectivity, we propose two configurations of the opticalcompensators with multiple focusing modes. For the first type, the electrodesare divided into several circular ring divisions, which are applied with differentvoltages for resulting in different optical path modulations in the regions. Thatwill be effective to a graded-index refractive lens. Besides, the positive ornegative focusing mode can be switched by the polarization of applied voltageson the ring electrodes. For the second type, the Fresnel zone andcomplementary electrodes are adopted and accompanied with the technology ofpolymer stabilized liquid crystal (PSLC) for generating the purpose of multiplemodes. Both configurations can be used to the optical system design ofautofocusing cameras for compensating the focal length of the lens andgenerating different focal positions. Also, it can be applied to the opticalapparatus that requires multiple focusing characteristics.The preliminary optical simulations and experiments have been performedto convince the feasibility of the study. In the project execution, the furtheranalysis of optical properties of LCs and practical realization of the device willbe proceeded to. Furthermore, the device will be combined with the lensmodule for the verification of the image formation.This project is a plan with the duration of three years. The first year's goalwill be focused on the literature and theoretical study, and the practicalrealization of the first configuration. Based on the results, the improvement ofthe compensator by using dual-layer electrodes will be performed in the secondyear. Finally, the implementation of the third configuration and thecharacteristics of the image formation will be confirmed in the third year

Study of the Laser Noise of the Blue-Light High-Density Optical Storage System(I)

在光儲存系統中雷射雜訊是一非常重要的問題。有多種機制會造成雷射之雜訊，特別是因雷射光反饋進入共振腔所導致的雜訊更為嚴重，並且是發展新世代光儲存技術之一重要課題。波長405nm 之藍光雷射已被規範為下世代高密度光碟之標準光源了。然而嚴格的藍光碟片讀取訊號之規格卻導致藍光雷射元件及光學讀寫頭之開發非常困難，特別是如何去降低雷射所造成之雜訊。本研究探討藍光雷射之反饋雜訊問題。建立在先前對650nm雷射之DVD系統的瞭解，我們建立405nm 雷射反饋雜訊之量測平台並研究其特性，其結果將對從事雷射元件或光學頭研究者提供良好之資訊。此外，本計畫亦將針對目前幾種有用之消除雜訊方法，例如採用四分之一波長片或以高頻調變之方式，作進一步之驗證，探討其於藍光系統之可行性，進而提出以液晶光學元件技術製作之可變相位四分之一波長片，以應用於未來多波長之藍光光學頭上

Study of Holographic Multiple-Beam Optical Pickup Head (II)

本研究延續先前之探討，設計全像型多光束微型光學讀寫頭之國科會計畫案(NSC 92-2215-E-005-004)。在第一年(92 年度)計畫中我們完成了光學系統與元件之設計，並以液晶繞射光學元件(LCDOE)之技術來製作多光束光柵與全像光學元件(HOE)，本第二年計畫(93 年度)，我們將利用此二液晶繞射光學元件搭配雷射、透鏡及光偵測器進行光學頭系統之驗證，以實現具有多光束讀取之可寫式全像型光學頭的構想

Design and Fabrication of In-Line Gratings for the Blu-Ray Optical Pickup Head

應用於藍光讀寫頭之同軸式光柵設計與製作反向相容是光儲存系統進展之一重要議題。其在過去之 DVD 系統已非常明顯，也在現今之藍光系統顯露無遺。在這發展中，單體雙波長積體式之雷射二極體(TWIN-LD)是一重要改進，其整合兩雷射共振腔於單一封裝，一為650nm 雷射波長，另一則為780nm 雷射波長。此進展大幅簡化光學系統之設計，將原本複雜之架構變成單一光路之架構。也因此降低製造成本與組裝之複雜度。在此情形下，單體三波長積體式雷射二極體亦正積極地被開發中，在未來即將被應用於實現單一光路具有三種雷射波長的光學讀寫頭系統上。鑑於此，本計畫結合台睿科技公司之合作，進行可適用於單一光路三波長光學讀寫頭之使用的同軸光柵設計與製作。我們將採用二維分區陣列式之概念來設計此同軸光柵，藉由純量繞射理論與光學模擬軟體之分析，得到最佳之同軸光柵設計。進而經由微製造之技術製作此同軸光柵。最後，此元件更將被組裝於雷射二極體上以實現單一光路三波長光學讀寫頭之目的。Design and fabrication of in-line gratings for the Blu-ray optical pickup headBackward compatibility is one of the important issues on the progress of optical storagesystems. It had been very clear on the past DVD development and is also apparent in thecurrent Blu-ray systems. One important improvement is the birth of the monolithictwo-wavelength integrated laser diode (TWIN-LD). It integrates two laser cavities, one forthe 650 nm wavelength and the other for the 780nm wavelength, in a single package. Thatgreatly simplifies the optical system design from two complicated paths to one simple pathand therefore reduces the manufacturing cost as well as the assembly complexity. Under thecircumstances, the monolithic three-wavelength integrated laser diode is currentlyaggressively developed. It will be soon applied to the Blu-ray system for achieving asingle-path optical pickup head with three laser wavelengths.Under the consideration, this project is proposed to develop an in-line grating, which isapplicable to the use of the single-path optical pickup head with three laser wavelengths, inconjunction with the support of TopRay Technology Inc. We will adopt the concept oftwo-dimensional segmented matrix to design the in-line grating pattern. With the analysis ofscalar diffraction theory and optical simulation software, the optimized design will beobtained. Furthermore, the grating will be produced by using the technology of microfabrication. Finally, this device will be assembled to the laser diode for realizing asingle-path three-wavelength optical pickup head

Integrated optical unit design for the collinear holographic storage system

The optical configuration proposed by Optware Corporation has the features of recording the holographic versatile disk (HVD) and backwardly retrieving CD and DVD. This paper presents a novel design that applies the technology of integrated optical unit to the HVD system. This unit comprises a holographic optical element for splitting light and generating servo signal. A transmissive spatial light modulator (SLM) with central data part and outer-ring reference part is adopted for modulating the laser beams. A new outer-ring polarizer is accompanied with the SLM. Two lasers, one with 532 nm for the HVD and the other with 650 nm for the CD/DVD, are included in the unit. Analysis for the system was performed. Simulation results show the feasibility for implementing an integrated collinear holographic system with miniaturized size

Multiple-beam liquid crystal grating for the recordable optical pickup head

By combining the technology of a liquid crystal diffractive optical element with that of a multiple-beam grating, a novel multiple-beam liquid crystal grating is proposed for the application of recordable optical pickup heads. This grating has the function of generating seven diffracted beams with equal intensity in each order while applying a voltage to the device. It provides the switching ability between the single beam and multiple beams for writing data and reproducing data, respectively