1310183 九、發明說明： 【發明所屬之技術領域】 ’ 本發明係有關光學讀寫頭（optical pickup)，特別是關 於一種備有反射锻膜裝置（coating device)之光學讀寫頭。 【先前技術】1310183 IX. Description of the Invention: [Technical Field of the Invention] The present invention relates to an optical pickup, and more particularly to an optical pickup equipped with a reflective forging device. [Prior Art]
音樂光碟片（Compact Disk，CD)、影像光碟片（video Compact Disk ’ VCD)及數位式影像光碟片（Digital VideoMusic Disc (CD), Video Compact Disk (VCD) and Digital Video Disc (Digital Video)
Disk ’ DVD)已被廣泛使用於企業、家庭及個人的生活四周， 所以相關業界無不致力於研發更有效率的讀取或記錄之技 術，以提昇CDs、VCDs及DYDs如此類記錄媒體的品質。 光學讀寫頭經由記錄媒體（recordi ng)讀取或記錄資 料。雷射二極體（laser diode，LD)發射之光源透過光學元件 組(optical element、set)聚焦於記錄媒體的表面，光訊號檢 出器（photo detector integrated circuit，PDIC)接收或檢 測其反射強弱訊號。 第一圖為一種習知之光學讀寫頭之結構示意圖。此光學 讀寫頭包括一記錄媒體101、一光訊號檢出器102、一雷射二 極體 103、一偏極化分光鏡(polarized beam splitter)104、 一四分之一波片（quarter wave plate)105、一準直透鏡 (collimator lens)106 及一物鏡(objective lens)107。 雷射二極體103發射之雷射光源經由偏極化分光鏡104、 四分之一波片105、準直透鏡106、物鏡107後、聚焦於記錄 媒體101的表面。此光學讀寫頭利用此記錄媒體101讀取或 記錄資料。此雷射光源再經由記錄媒體101表面的反射，透 過物鏡107、準直透鏡106、四分之一波片105及偏極化分光 鏡104被導至光訊號檢出器102。由光訊檢出器102偵測其 強弱訊號。 此光學讀寫頭係利用多個光學透鏡及偏極化分光鏡的組 合’將光源反射及導引至記錄媒體101與光訊號檢出器1〇2， 而達到讀取或記錄資料及偵測訊號強弱的目的。 偏極化分光鏡104係用來穿透及反射雷射光。由於其材 質選擇與製作品質的因素，.導致元件價格居高不下。 此雷射光源的出射光及反射光之路徑係由雷射二極體 103至記錄媒體101的表面反射至光訊號檢出器1〇2。 由於此光學讀寫頦之偏極化分光鏡104及四分之一波片 105需較向之製作工藝及繁瑣之製程，不僅實施及製作過程 極為複雜，而且也提高其生產成本。 【發明内容】 本發明提出一種備有反射鍍膜裝置之光學讀寫頭，主要 包含有-雷射二極體元件、—光學元件、一記錄媒體、—光 5札號檢出器。雷射二極體元件發射1—3種不同波長，但相同 線偏振方向之光源。光源經由光學元件組聚焦至記錄媒體， 作記錄及讀取的動作，再由記錄媒體的表面反射並再次透過 光學元件’導引至光訊號檢出器來偵測強弱訊號。 此光學元件包括一分光元件、一反射鍍膜裝置及—物 鏡。其分光元件將1光束分為3光束。反射鍍膜裝置有反射 及穿透射雷射光，以及轉變該雷射光波長1、波長2、波長3 之1或2或3種波長的相位角差及線偏振方向的功能。此光 學元件可加入耦合鏡來調整該雷射光之準直度與增加光耦合 效果，此耦合鏡是一選配(0pti〇nai)元件。物鏡用以聚焦雷 射光。 雷射一極體元件將相同線偏振方向的雷射光，以一角度 α入射反射鍍膜裝置，將卜3種波長轉變為圓偏振光或橢圓 偏振光。經由記錄媒體之表面反射再次經反射鍍膜裝置將1〜3 種波長轉變為線偏振光，並回饋（feedback)至一雷射二極發 光腔體（laser diode cavity)。此回饋之線偏振光（linear polarized light)與原始線偏振光之角度改變為9〇。。 此反射鍍膜裝置可由一片或一片以上之反射鏡，或—片 以上之反射鏡與穿透鏡組合而成。 藉由此反射鍍膜裝置將入射光之線偏振角度與回饋光 (feedback)之線偏振角度改變9〇。，因此達到降低雷射二極體 因§己錄媒體回饋光而產生之相對強度雜訊（relahve intensity noise)之目的。 茲配合下列圖示、實施例之詳細說明及申請專利範圍， 將上述及本發明之其他目的與優點詳述於後。 【實施方式】 第二圖為本發明之光學讀寫頭的一個結構示意圖。此光 學讀寫頭包含一光學元件204、一雷射二極體元件2〇3、一記 錄媒體201和一光訊號檢出器202。此光學元件2〇4更包括 —分光元件204a、一反射鍍膜裝置204b、和一物鏡2〇4d。 雷射二極體203發出1-3種不同波長，λ i-；b，但具有 相同偏振方向之線偏振光。此線偏振光經由分光元件2〇4a、 反射鍍膜裝置204b、耦合鏡204c(隨意的）、物鏡2〇4d投射 於一記錄媒體上201。然後經由記錄媒體201之表面依序反 射至物鏡204d、耦合鏡204(：、和反射鍍膜裝置20413。穿過 反射鍍膜裝置204b之光束由光訊號檢出器202接收與檢測。 而由反射鑛·膜裝置204b反射之光束，最後回饋至雷射二極體 發光腔體203a。 記錄媒體201利用所發射之雷射光來記錄或讀取資料。 光訊號檢出器202接收記錄媒體201反射之雷射光，並偵測 此雷射光之強弱訊號。分光元件2〇4a，如光柵，將雷射光由 —光束分為三光束。物鏡2〇4d為固定焦距，將雷射光聚成一 點。耗合鏡204c使雷射光成為準直光束，是一選配元件。反 射錄膜裝置2G4b使-部分之雷·穿透，另—部分反射，具 有透射及反射之功能。 如第二圖所示，當雷射二極體203發出卜3種不同波長， λ广λ3 ’但具有相同偏振方向1〇9之線偏振光後，線偏振光 以角度α(蒼照第四圖）及入射角$經反射鐘膜裝置職 將波長；11久3之1或2或3種不同波長轉變為圓偏振光 或橢圓偏振光108。此圓偏振光通或橢圓偏振光⑽經由記 錄媒體201之表面反射，仍為圓偏振光⑽或觀偏振光 108，再次經反射鑛膜裝置難，將波長入入3之i或2或3 種波長轉㈣線偏振光UQ，並回饋至雷射二極體發光腔體 203a。 . 此反射鑛膜裝置2〇4b係由-片或-片以上之反射鏡，或 片以上之反射鏡與穿透鏡組合而成，使回饋至雷射二極體 發光腔體2G3a m偏振光與原、始線偏振光之肖度改變達到 90。。 不失一般性，第三圖以具有2片反射鏡之反射鍍膜裝置 為例，來說明本發明之光學讀寫頭的一個實施例。。在第三 圊中，藉由反射鏡3Q41與綱2之組合組合而成的反射錄膜 裝置3G4b來達到改變回饋光21G與出射光2〇9之線偏振角度 改變90°。 第四圖說財如种，雷射二極體絲之線偏振方向與 1310183 反射鍍犋裝置之入射角兩者之間的安排。參考第四圖，此雷 射二極體光源之線偏振方向109以一角度α入射反射鍍膜裝 置及與反射鑛膜裝置的入射角万。此種安排藉由反射錄膜裝 置將波長;Ιρ·λ3之1或2或3種波長之“Ρ”，態(p state)與 S 態（S state)的相位角差（phase angie delay)延遲為 9〇〇 —6〇亦即轉成為圓偏振光1〇8(相位角差90。）或橢圓偏振光 1〇8(相位角差在％〜150。）。線偏振光的肖度的範圍可在 • 1〇。〜別。之間或⑽。，。。入射角/3的範圍可在15、85。 之間。 第三圖中，出射光2〇9經反射鍍膜裝置304b的兩片反射 鏡_與3042將波長又广又3之1或2或3種不同波長轉變 為圓偏振光108 _圓偏振光1〇8。此圓偏振光1〇8或擴圓偏 振光⑽經由記錄媒體201表面，反射此圓偏振光⑽或搞 圓偏振光108，再-次經過反射被膜裝置的兩片反射鏡綱 • 與3〇42’使波長λι—L之1或2或3種波長之“p”態(pstate) 與“S”態（S State)的相位角差18〇。，亦即與原始線偏振方 向109約呈90。之線偏振方向11〇 ’並回饋至雷射二極體發光 腔體203a。 依此反射鍍職置_將出射光之線偏振角度與回 饋光（feedbaCk)210之線偏振角度改變9〇D。因此達到降低雷 ^射二極體因記錄媒體回饋光21Q而產生之相對強度雜訊的目田 的0 10 1310183 本發明之光學讀寫頭中，相關反射鍍獏裝置技術的成本 少於習知技術，因此相對地減少生產成本。且此技術有效地 控制雷射二極體對回饋光之相對強度雜訊的產生，進而提昇 相關業者的競爭力。 惟，以上所述者，僅為本發明之例舉實施例而已，當不 能以此限定本發明實施之範I即大凡依本發”請專利蘇 圍所作之均等變化與修m仍屬本發明專利涵蓋之範圍 1310183 【圖式簡單說明】 第一圖為一種習知之光學讀寫頭之結構示意圖；’ 第二圖為本發明之光學讀寫頭的一個結構示意圖； 第二圖為具有2片反射鏡之反射鍍膜裝置為例，來說明本 發明之光學讀寫頭的一個實施例； 第四圖說明本發明中，雷射二極體光源之線偏振方向與反 射鍍膜裝置之入射角兩者之間的安排。 【主要元件符號說明】 101記錄媒體 , 102光訊號檢出器 ---—- 103雷射二極體 ----- 104偏極化分光鏡 ---~~~--- 106準直透鏡 105 四分之一波片 ——._ 107物鏡 1 —-—------- 108圓偏振光或橢圓偏振光 ' -- 109出射雷射光線偏据太今 1 - . · 11Π问錯堂春1*伞绩值iFtAr ----- 丄1U 巴/万貝由巧J 7U，咏Ί掏力问 201 記錄媒體 —__ 202光訊號檢出器 203雷射二極體 -— 203a雷射二極體發光腔體 204光學元件 ----^_ — 204a分光元件（光柵） 204b反射鍍膜裝置 —'^-~~~__ 204c耦合鏡 204d物鏡 209出射光 1310183 210 回饋光 λ丨-λ3波長1-波長3 入射角/3 * 201 記錄媒體 202光訊號檢出器 203 雷射二極體 203a雷射二極體發光腔體 204a分光元件（光柵） 204c搞合鏡 204d物鏡 3041，3042反射鍍膜裝置 109出射雷射光線偏振方向 203雷射二極體 203a雷射二極體發光腔體 204a分光元件（光柵）Disk 'DVD' has been widely used in the life of businesses, families and individuals, so the relevant industry is committed to developing more efficient reading or recording technology to improve the quality of such recording media such as CDs, VCDs and DYDs. . The optical pickup reads or records data via a recording medium. The light source emitted by the laser diode (LD) is focused on the surface of the recording medium through an optical element (set), and the photodetective circuit (PDIC) receives or detects the intensity of the reflection. Signal. The first figure is a schematic structural view of a conventional optical pickup. The optical pickup includes a recording medium 101, an optical signal detector 102, a laser diode 103, a polarized beam splitter 104, and a quarter wave. A plate 105, a collimator lens 106, and an objective lens 107. The laser light source emitted from the laser diode 103 is focused on the surface of the recording medium 101 via the polarization beam splitter 104, the quarter wave plate 105, the collimator lens 106, and the objective lens 107. This optical pickup uses this recording medium 101 to read or record data. The laser light source is further reflected by the surface of the recording medium 101, and is guided to the optical signal detector 102 through the objective lens 107, the collimator lens 106, the quarter-wave plate 105, and the polarization beam splitter 104. The strong signal is detected by the optical detector 102. The optical head uses a combination of a plurality of optical lenses and a polarizing beam splitter to reflect and direct the light source to the recording medium 101 and the optical signal detector 1〇2 to achieve reading or recording of data and detection. The purpose of the signal strength. The polarized beam splitter 104 is used to penetrate and reflect the laser light. Due to the choice of materials and the quality of the production, the price of components is high. The path of the outgoing light and the reflected light of the laser light source is reflected from the surface of the laser diode 103 to the recording medium 101 to the optical signal detector 1〇2. Since the polarized beam splitter 104 and the quarter-wave plate 105 of the optical read/write device need to be relatively complicated in manufacturing process and cumbersome process, the implementation and manufacturing process are extremely complicated, and the production cost is also increased. SUMMARY OF THE INVENTION The present invention provides an optical pickup provided with a reflective coating device, which mainly includes a --polar diode element, an optical element, a recording medium, and a light detector. The laser diode element emits 1-3 sources of different wavelengths but the same linear polarization direction. The light source is focused to the recording medium via the optical element group for recording and reading, and is then reflected by the surface of the recording medium and redirected through the optical element to the optical signal detector to detect the strong and weak signals. The optical component includes a beam splitting element, a reflective coating device, and an objective lens. The light splitting element splits the 1 beam into 3 beams. The reflective coating device has a function of reflecting and transmitting transmitted laser light, and converting a phase angle difference and a linear polarization direction of the laser light having a wavelength of 1, a wavelength 2, a wavelength of 1 or 2 or 3 wavelengths. The optical component can be incorporated into a coupling mirror to adjust the collimation of the laser light and to increase the optical coupling effect. The coupling mirror is an optional (0pti〇nai) component. The objective lens is used to focus the laser light. The laser-polar element converts the laser light of the same linear polarization direction into the reflective coating device at an angle α, and converts the three kinds of wavelengths into circularly polarized light or elliptically polarized light. One to three wavelengths are converted into linearly polarized light by a reflective coating device via the surface reflection of the recording medium, and fed back to a laser diode cavity. The angle of the linear polarized light and the original linearly polarized light is changed to 9 〇. . The reflective coating device may be formed by one or more mirrors or a combination of a mirror and a lens. By this reflective coating device, the linear polarization angle of the incident light and the linear polarization angle of the feedback are changed by 9 。. Therefore, the purpose of reducing the relative intensity noise of the laser diode due to the feedback light of the recorded media is achieved. The above and other objects and advantages of the present invention will be described in detail with reference to the accompanying drawings. Embodiments The second figure is a schematic structural view of an optical pickup of the present invention. The optical pickup includes an optical component 204, a laser diode component 2〇3, a recording medium 201, and an optical signal detector 202. The optical element 2〇4 further includes a light splitting element 204a, a reflective coating device 204b, and an objective lens 2〇4d. The laser diode 203 emits 1-3 different wavelengths, λ i-; b, but has linearly polarized light of the same polarization direction. This linearly polarized light is projected onto a recording medium 201 via the spectral element 2〇4a, the reflective coating device 204b, the coupling mirror 204c (optional), and the objective lens 2〇4d. Then, the surface of the recording medium 201 is sequentially reflected to the objective lens 204d, the coupling mirror 204 (:, and the reflective coating device 20413. The light beam passing through the reflective coating device 204b is received and detected by the optical signal detector 202. The light beam reflected by the film device 204b is finally fed back to the laser diode cavity 203a. The recording medium 201 records or reads data using the emitted laser light. The optical signal detector 202 receives the laser light reflected by the recording medium 201. And detecting the strong and weak signal of the laser light. The splitting element 2〇4a, such as a grating, splits the laser light into three beams by the beam. The objective lens 2〇4d is a fixed focal length, and the laser light is concentrated into a point. The laser light is a collimated beam, which is an optional component. The reflective filming device 2G4b has a portion of the lightning penetration and another partial reflection, and has the functions of transmission and reflection. As shown in the second figure, when the laser is used The diode 203 emits three different wavelengths, λ wide λ3 'but after linearly polarized light having the same polarization direction of 1 〇 9 , the linearly polarized light is reflected by the angle α (the fourth picture of the sun) and the incident angle of $ Device duty wavelength 11 or 3 or 3 different wavelengths are converted into circularly polarized light or elliptically polarized light 108. The circularly polarized light or elliptically polarized light (10) is reflected by the surface of the recording medium 201, and is still circularly polarized (10) or polarized. The light 108 is again difficult to be reflected by the mineral film device, and the wavelength is input into the 3 or 2 or 3 wavelengths of the (4) linearly polarized light UQ and fed back to the laser diode cavity 203a. The reflective ore film device 2〇4b is a combination of a mirror or a mirror, or a combination of a mirror and a lens, for feedback to the laser diode 2G3a polarized light and original polarization The lightness of the light changes to 90. Without loss of generality, the third figure illustrates an embodiment of the optical pickup of the present invention by taking a reflective coating device having two mirrors as an example. The linear recording angle of the change feedback light 21G and the outgoing light 2〇9 is changed by 90° by the reflective recording film device 3G4b combined with the combination of the mirror 3Q41 and the frame 2. The fourth picture shows the kind of money, the laser II Between the linear polarization direction of the polar body filament and the incident angle of the 1310183 reflective rhodium plating device Arrangement. Referring to the fourth figure, the linear polarization direction 109 of the laser diode source is incident on the reflective coating device at an angle α and the incident angle with the reflective ore film device. Ρρ·λ3 of 1 or 2 or 3 wavelengths of “Ρ”, the phase angie delay of the p state and the S state is delayed by 9〇〇—6〇, that is, into a circle. Polarized light 1〇8 (phase angle difference 90.) or elliptically polarized light 1〇8 (phase angle difference is %~150.) The range of linearly polarized light can be in the range of • 1 〇. (10)..... The angle of incidence / 3 can be in the range of 15, 85. between. In the third figure, the exiting light 2〇9 is converted into circularly polarized light 108 by the two mirrors _ and 3042 of the reflective coating device 304b by a wide range of wavelengths and 3 or 2 or 3 different wavelengths. 8. The circularly polarized light 1〇8 or the circularly polarized light (10) passes through the surface of the recording medium 201, reflects the circularly polarized light (10) or circularly polarized light 108, and passes through the two mirrors of the reflective film device and 3〇42. 'The phase angle difference between the "p" state (pstate) of the wavelength λι-L of 1 or 2 or 3 wavelengths and the "S" state (S State) is 18 〇. That is, approximately 90 with the original linear polarization direction 109. The linear polarization direction 11 〇 ' is fed back to the laser diode cavity 203a. According to the reflection plating position, the linear polarization angle of the outgoing light and the linear polarization angle of the feedback light (feedbaCk) 210 are changed by 9 〇 D. Therefore, in the optical pickup head of the present invention, the cost of the related reflective rhodium plating device is lower than that of the conventional optical head in which the relative intensity noise generated by the recording medium feedback light 21Q is reduced. Technology, thus relatively reducing production costs. Moreover, this technology effectively controls the generation of the relative intensity noise of the laser diode to the feedback light, thereby enhancing the competitiveness of the relevant industry. However, the above description is only an exemplified embodiment of the present invention, and it should not be construed as limiting the implementation of the present invention, that is, the equivalent change and repair of the patent is still the present invention. Patent Coverage Range 1310183 [Simple Description of the Drawings] The first figure is a schematic structural view of a conventional optical reading head; 'The second figure is a schematic structural view of the optical reading head of the present invention; the second figure has 2 pieces The reflective coating device of the mirror is taken as an example to illustrate one embodiment of the optical pickup of the present invention. The fourth figure illustrates both the linear polarization direction of the laser diode source and the incident angle of the reflective coating device in the present invention. Arrangement between [Main component symbol description] 101 recording media, 102 optical signal detector-----103 laser diode-----104 polarized beam splitter---~~~- -- 106 collimating lens 105 quarter wave plate --. _ 107 objective lens 1 --- --- 108 circularly polarized light or elliptically polarized light ' -- 109 out of the laser light is too far 1 - . · 11Π问错堂春1*Umbrella value iFtAr ----- 丄1U 巴/万贝由巧 J 7U,咏Ί掏力问201 Recording Media—__ 202 Optical Signal Detector 203 Laser Diode-- 203a Laser Diode Light Emitting Cavity 204 Optical Element----^_ — 204a Spectroscopic Element (Raster) 204b Reflection Coating device—'^-~~~__ 204c coupling mirror 204d objective lens 209 emitted light 1310183 210 feedback light λ丨-λ3 wavelength 1-wavelength 3 incident angle/3* 201 recording medium 202 optical signal detector 203 laser diode Body 203a laser diode cavity 204a beam splitting element (grating) 204c lens 204d objective lens 3041, 3042 reflective coating device 109 emitting laser light polarization direction 203 laser diode 203a laser diode cavity 204a splitting element (grating)