HD-2007-0022-TW 25642twf，doc/n 九、發明說明： 【發明所屬之技術領域] 本發明是有關於一種光學系統，且特別是有關於一種 投影機的光學系統。 【先前技術】 在現代，投影機被廣泛的使用在不同的場合，像是會 議、教學及娛樂的場合。因此，具備高晝質、低價格、高 亮度及低耗電的投影機將成為趨勢。 依照習知，投影機包括投射鏡及光學系統。圖1A為 說明習知光學系統。參照圖1A，習知光學系統〗〇〇具有光 源 110、偏極分光鏡（polarizing beam splitter，簡稱 PBS)120、光閥(light value)130、檢偏鏡(analyzer)140 及鏡 頭(lens)150。偏極分光鏡120配置於光源i10發射的光線 束L10所行經的光線路徑上，在經過偏極分光鏡12()後光 線束L10分為具有S偏極的第一光線束L12及具有p偏極 的第二光線束L14。第一光線束L12會被偏極分光鏡12〇 反射，第二光線束L14則穿透偏極分光鏡12〇。第—光線 束L12接著被光閥130反射並且轉換為具p偏極的影像光 束L20。影像光束L20會穿透偏極分光鏡12〇、檢偏鏡mo 及鏡頭150。 圖1B為說明另一習知光學系統。請參照圖1B，圖汨 的習知光學系統l〇0a與圖1A的光學系統1〇〇不同之處於 光學系統100a更包括配置於光源110及偏極分光鏡1加 HD-2007-0022-TW 25642twf.doc/n 之間的偏極片160。偏極片MO會傳送具有S偏極的第一 光線束L12 ’同時反射具有P偏極的第二光線束L14。藉 此’只有第一光線束L12能夠到達偏極分光鏡120及光閥 130並且被轉換為影像光束L2〇。 【發明内容】 對應上述’本發明應用於光學系統，使光學系統具有 更好的效能及更高的效率。 本發明提出一種光學系統，用以提供影像光束，其包 括光源、光束分離/結合裝置、及光閥。光源用以提供光線 束光束;7離/結合裝置包括第一偏極分光鏡、第二偏極分 光鏡、四分之一波片（quarter wave plate，簡稱QWP)及反射 益。第一偏極分光鏡反射來自光源的光線束中的第一光線 束並且來自光源的光線束中的第二光線束會穿透第一偏極 分光鏡。來自第一偏極分光鏡的第二光線束會穿透第二偏 極分光鏡及四分之一波片，經反射器反射後，穿透四分之一 波片，接著被第二偏極分光鏡反射。光閥將來自第一偏極 分光鏡的第一光線束及反射自第二偏極分光鏡的第二光線 束轉換為影像光束。 根據本發明之一實施例中’上述之光學系統更包括檢偏 鏡’其配置於影像光束的光學路徑上。 根據本發明之一實施例中，上述之反射器為反射層且鍍 於四分之一波片上。 根據本發明之一實施例中’上述之第一偏極為S偏極及 1339315 HD-2007-0022-TW 25642twf.doc/n 上述之第二偏極為p偏極。 根據本發明之一實施例令，上述之第一偏極為p偏極及 • 上述之第二偏極為S偏極。 本發明另提出一種光學系統，用以提供影像光束，其 包括光源、光束分離/結合裝置及光閥。光源用以提供光線 束。光束分離/結合裝置包括第一偏極分光鏡、第二偏極分 光鏡、二分之一波片㈣fwaveplate，簡稱Hwp)及反射器。 • 第二偏極分光鏡反射來自光源的第一光線束並且來自光源 的第二光線束會穿透第一偏極分光鏡。來自第一偏極分光 鏡的第二光線束會穿透二分之一波片。第二偏極分光鏡反 射來自二分之一波片的第二光線束。光閥將反射自第—偏極 刀光鏡的苐一光線束轉換為穿透第一偏極分光鏡的第一影 像光束，並且將反射自第二偏極分光鏡的第二光線束轉換 為穿透第二偏極分光鏡的第二影像光束，其中第一影像光 束結合第二影像光束形成影像光束。 根據本發明之-實關巾’上述之光H统更包括檢偏 鏡’其配置於影像光束的光學路徑上。 根據本發明之-實施例中，上述之第—偏極為s偏極及 上述之苐二偏極為ρ偏極。 根據本發明之-實施例中，上述之第—偏極為p偏極及 上述之第二偏極為s偏極。 本發明又提出-種光學系統，用以提供影像光束，其 包括光源、光束分離/結合裝置及光閥。光源用以提供光ς 束。光束分離/結合裝置包括第—偏極分光鏡、第二偏極分 HD-2007-0022-TW 25642twf.doc/n 光鏡、四分之一波片、第一反射器及第二反射器。第一偏極 分光鏡反射來自光源的第一光線束並且來自光源的第二光 線束會穿透第一偏極分光鏡。第二偏極分光鏡會反射來自 第一偏極分光鏡的第二光線束。反射自第一偏極分光鏡的 第一光線束會穿透四分之一波片。第一反射器反射來自四 分之一波片的第一光線束，其中被第一反射器反射的第一 光線束會穿透四分之一波片及第一偏極分光鏡。第二反射 器會反射穿透自第一偏極分光鏡的第一光線束，其中被第 二反射器反射的第一光線束會被第二偏極分光鏡反射。光 閥將來自第二偏極分光鏡的第一光線束轉換為穿透第二偏 極分光鏡的第一影像光束，並且將來自第二偏極分光鏡的 第二光線束轉換為穿透第二偏極分光鏡的第二影像光束， 其中第一影像光束結合第二影像光束形成影像光束。 根據本發明之一實施例中，上述之光學系統更包括檢偏 鏡’其配置於影像光束的光學路徑上。 根據本發明之一實施例中，上述之第一偏極為s偏極及 上述之弟一偏極為P偏極。 根據本發明之-實施例中，上述之第一偏極為p偏極及 上述之第二偏極為s偏極。 本發明再提出一種光學系統，用以提供影像光束，其 包括光源、光束分離/結合裝置及光閥。光源用以提供光線 束。光束t離/結合H包括第—偏極分紐、第二偏極分 光鏡、二分之一波片（half wave plate，簡稱Hwp)及反射器。 第一偏極分光鏡反射來自光源的第—光線束並且來自^源 HD-2007-0022-TW 25642twf.doc/n 的第二光線束會穿透第一偏極分光鏡。第二偏極分光鏡反 射來自第一偏極分光鏡的第一光線束。來自第一偏極分光 鏡的弟一光線束會穿透二分之一波片。反射器反射來自二 分之一波片的第二光線束，其中反射自反射器的第二光線 會被第二偏極分光鏡反射。光閥將來自第二偏極分光鏡的 第一光線束轉換為穿透第二偏極分光鏡的第一影像光束， 並且將來自第二偏極分光鏡的第二光線束轉換為穿透第二 偏極分光鏡的第二影像光束，其中第一影像光束結合第二 影像光束形成影像光束。 根據本發明之一實施例中，上述之光學系統更包括檢偏 鏡，其配置於影像光束的光線路徑上。 根據本發明之-實施例中，上述之第—偏極為s偏極及 上述之弟二偏極為p偏極。 根據本發明之-實施例中，上述U極為p偏極及 上述之弟二偏極為s偏極。 如上述本發明的實施例，第一光線束及第二光 會被轉換為影像光束。藉此，本發明實 光^ 統具有更好的效能及更高的效率。 Μ先干糸 為讓本發明之上述特徵和優點能更明顯易懂 舉貫施例，並配合所_式，作詳細說明如下。 · 實施方式】 以下的敘述將伴隨著實施例的圖示 所提出之實施例進行說明。在各圖示中所使用相 HD-2007-0022-TW 25642twf.doc/n 的參考標號，是用來敘述相同或相似的部份。 圖2為說明根據本發明一實施例的光學系統。參照圖 2，光學系統200提供影像光束(image beam)L40，其包括 光源210、光束分離/結合裝置（beam splitting/combining device)22〇、及光閥(light value)230。光源210提供光線束 (illumination beam)L30，光線束L30包括具有第一偏極D1 的第一光線束L32及具有第二偏極D2的第二光線束L34 的，並且光束分離/結合裝置220配置於光線束L30所行經 的光線路徑上。光束分離/結合裝置220包括第一偏極分光 鏡(polarizing beam splitter ’ 簡稱 PBS)222、第二偏極分光 鏡 224 及四分之一波片（quarter wave plate，簡稱 QWP)226 及反射器228。 第一偏極分光鏡222反射來自光源210且具有第一偏 極D1的第一光線束到光閥230以及傳送來自光源210且 具有第二偏極D2的第二光線束。來自第一偏極分光鏡的 第二光線束L34會穿透第二偏極分光鏡224及四分之一波 片226 ’接著被反射器228反射。反射自反射器228的第 二光線束L34在穿透四分之一波片226後被轉換成具有第 一偏極D1的第二光線束’接著被第二偏極分光鏡224反 射進光閥230。光閥230將來自第一偏極分光鏡222的第 —光線束L32轉換為第一影像光束L42並且將反射自第二 偏極分光鏡224的第二光線束L34轉換為第二影像光束 L44。第一影像光束L42及第二影像光束L44皆具有第二 偏極D2，並且第一影像光束L42及第二影像光束L44會 HD-2007-0022-TW 25642twf.doc/n 各自穿透第一偏極分光鏡222及第二偏極分光鏡224，將 第一影像光束L42及第二影像光束L44結合以形成影像光 束 L40。 光學系統200利用第二偏極分光鏡224及反射器 228 ’導致轉換成影像光束L40的不只第一光線束L32，連 第二光線束L34也會被轉換成影像光束L40。藉此，光學 系統200具有更高的效率及更好的效能，因此提昇了使用 光學系統200之投影機的影像品質。 光學系統200可以被應用於投影機30〇。圖3為說明 根據本發明一實施例的投影機。參照圖3，投影機3〇〇具 有光學系統200及投影鏡頭310。投影鏡頭310配置於來 自光學系統200的影像光束L40的光線路徑上。投影鏡頭 310投射影像光束L40於銀幕(未繪示)上以形成影像(未繪 示）。此外，光學系統200可以更包括檢偏鏡240，其配置 於影像光束的光線路徑上，並且位於第一偏極分光鏡 222、第一偏極分光鏡224及投影鏡頭310之間。檢偏鏡 240更強化影像光束L40的偏極以提昇影像的對比。 第一偏極D1可以為S偏極，同時第二偏極D2可以 為P偏極。不過，第一偏極D1同樣可以為p偏極，同時 第二偏極D2可以為S偏極。第一及第二偏極分光鏡222、 224可以為金屬線網偏振片（wire_grid p〇iarizer，簡稱 WGp)、薄膜偏振片（thin-film polarizer ’ 簡稱 TFP)、聚合 物薄膜偏振片（polymer-film polarizer，簡稱PFP)，以立體 或平板的形式實現。光閥230可以為反射型光閥，例如為 1339315 HD-2007-0022-TW 25642twf.doc/n 矽基液晶（liquid crystal on silicon，簡稱為 LCOS)。此外， 反射器228及四分之一波片226可以為其他可據以實現的 裝置。圖4為說明圖2光學系統的其他實施方式。參照圖 4 ’本實施例中’反射器228可以為反射層且鑛於四分之一 波片226上。 值得注意的是，上述的光學系統200己揭露本發明的 實施方式。然而’光學系統同樣可以用其他方式實現。下 述會再揭露幾個其他的實施方式。特別要注意的是接下來 的實施方式會與圖2所述之實施例部份相似。且接下來的 實施例與圖2之實施例相同或相似的地方會使用相同或相 似的標號。下述會敘述其他實施例與圖2之實施例不同之 處。 圖5、圖6A到圖6C及圖7為說明根據本發明一實施 例的光學系統。參照圖5 ’光學系統200a中的光束分離/ 結合裝置220a包括第一偏極分光鏡222、第二偏極分光鏡 224 及二分之一波片（half wave plate，簡稱 HWP)226a。第 一偏極分光鏡222反射來自光源210且具有第一偏極D1 的第一光線束L32到光閥230，同時傳送來自光源210且 具有第二偏極D2的第二光線束L34。來自第一偏極分光 鏡222的第二光線束L34接著會穿透二分之一波片226a 並且轉換成具有第一偏極D1的第二光線束L34。第二偏 極分光鏡224反射來自二分之一波片226a的第二光線束 L34進光閥230。第一影像光束L42及第二影像光束L44 皆具有第一偏極D2，並且第一影像光束L42及第二影像 12 1339315 HD-2007-0022-TW 25642twf.doc/n 光束L44會各自穿透第一偏極分光鏡222及第二偏極分光 鏡224 ’將第一影像光束L42及第二影像光束L44結合以 形成影像光束L40。 參照圖6A到6C。圖6A為本發明一實施例之光學系 統立體圖。圖6B為圖6A光學系統的前視圖。圖6C為圖 6A光學系統的側視圖。參照圖6A到6C，光學系統200b 中的光束分離/結合裝置220b包括第一偏極分光鏡222、 第二偏極分光鏡224、四分之一波片226、第一反射器228, 及第二反射器228”。特別注意的是，為了更清楚的說明， 圖6中的四分之一波片226及第一反射器228,為結合於為 一物件。不過’四分之一波片226及第一反射器228,在圖 2實施例中是可以各自分開配置的。第一偏極分光鏡222 反射來自光源210且具有第一偏極D1的第一光線束L32， 同時傳送來自光源210且具有第二偏極D2的第二光線束 L34。第二偏極分光鏡224反射來自第一偏極分光鏡222 的第二光線束L34到光閥230。第一光線束L32接著穿透 四分之一波片226，被第一反射器228’反射後，再次穿透 四分之一波片226’並且轉換成具有第二偏極£>2的第一光 線束L32。接著’第一光線束]穿透第一偏極分光鏡 222 ’被第二反射器228”反射，接著被第二偏極分光鏡224 反射到光閥230。光閥230會將來自第二偏極分光鏡224 的第一光線束L32及第二光線束134各自轉換為第一影像 光束L42及第二影像光束L44。第一影像光束L42及第二 影像光束L44皆具有第一偏極D1，其穿透第二偏極分光 13 1339315 HD-2007-0022-TW 25642twf.doc/n 鏡224並結合以形成影像光束L4〇。 在本實施例中’第二偏極分光鏡224的正規化向量V 與第一偏極分光鏡222、第一反射器228，、第二反射器228，， 及四分之一波片226的正規化向量（未繪示)形成的平面PL 交又’也就是說’第二偏極分光鏡224不能被放置於平面 PL ’並且影像光束的光線路徑可以垂直於平面Pl 值得注意的是’上述圖6A到6C的實施例中，關於第 一偏極分光鏡222的第二偏極D2可以為S偏極，除此之 外’關於第二偏極分光鏡224的第二偏極D2可以為P偏 極。在另一方面，關於第一偏極分光鏡222的第一偏極D1 可以為P偏極’除此之外’關於第二偏極分光鏡224的第 一偏極D1可以為S偏極。 參照圖7,光學系統200c中的光束分離/結合裝置220c 包括弟一偏極分光鏡222、弟一偏極分光鏡224、二分之·— 波片226c、反射器228。第一偏極分光鏡222反射來自光 源210且具有第一偏極D1的第一光線束L32，同時傳送 來自光源210且具有第二偏極D2的第二光線束L34。來 自第一偏極分光鏡222的第一光線束L32接著被第二偏極 分光鏡224反射到光閥340。來自第一偏極分光鏡222的 第一光線束L34穿透·一分之一波片226c後，被轉換成具 有第一偏極D1的第二光線束L34。第二光線束L34接著 被反射器228反射以及被第二偏極分光鏡224反射進光閥 230。光閥230會將來自第二偏極分光鏡224的第一光線束 L32及第二光線束L34各自轉換為第一影像光束L42及第 14 1339315 HD'20〇7-〇〇22-TW 25642twf.doc/n 二影像光束L44。第一影像光束L42及第二影像光束L44 白具有第二偏極D2,其穿透第二偏極分光鏡224並且結合 以形成影像光束L40。 值得注意的是，上述所揭露的光學系統可以如圖2同 樣的方式應用於投影機。 綜上所述，兩種偏極的光線束都會被轉換成影像光 束，也就是說，上述實施例中的光學系統可以利用比習知 光學系統更多的光線束。因此，上述實施例的光學系統具 有高效率及更好的效能，並且可以提昇使用本發明所述的 光學系統的投影機所投射的影像品質。 雖然本發明已以實施例揭露如上，然其並非用以限定 本發明，任何所屬技術領域中具有通常知識者，在不脫離 本發明之精神和範圍内，當可作些許之更動與潤飾，因此 本發明之保護範圍當視後附之申請專利範圍所界定者為 〇 【圖式簡單說明】 圖1A為說明習知光學系統。 圖1B為說明另一習知光學系統。 圖2為說明根據本發明一實施例的光學系統。 圖3為說明根據本發明一實施例的投影機。 圖4為說明圖2的光學系統其他實施方式。 圖5、圖6A到圖6C、圖7為說明根據本發明—每 例的光學系統。 Λ 15HD-2007-0022-TW 25642 twf, doc/n IX. Description of the Invention: [Technical Field] The present invention relates to an optical system, and more particularly to an optical system of a projector. [Prior Art] In modern times, projectors are widely used in different occasions, such as conferences, teaching, and entertainment. Therefore, projectors with high quality, low price, high brightness and low power consumption will become a trend. Conventionally, a projector includes a projection mirror and an optical system. Fig. 1A is a view showing a conventional optical system. Referring to FIG. 1A, a conventional optical system has a light source 110, a polarizing beam splitter (PBS) 120, a light value 130, an analyzer 140, and a lens 150. . The polarizing beam splitter 120 is disposed on the ray path of the light beam L10 emitted by the light source i10. After passing through the polarizing beam splitter 12(), the light beam L10 is divided into a first light beam L12 having an S-polarized pole and having a p-bias The second second light beam L14. The first light beam L12 is reflected by the polarization beam splitter 12 ,, and the second light beam L14 is transmitted through the polarization beam splitter 12 〇. The first light beam L12 is then reflected by the light valve 130 and converted into an image beam L20 having a p-polarity. The image beam L20 penetrates the polarizing beam splitter 12 〇, the analyzer mirror mo, and the lens 150. FIG. 1B is a diagram illustrating another conventional optical system. Referring to FIG. 1B, the conventional optical system 10a of FIG. 1A is different from the optical system 1 of FIG. 1A. The optical system 100a further includes a light source 110 and a polarizing beam splitter 1 plus HD-2007-0022-TW. Polar pole piece 160 between 25642twf.doc/n. The polarizer MO transmits a first ray bundle L12' having an S-polarity while reflecting a second ray bundle L14 having a P-polarity. By this, only the first light beam L12 can reach the polarization beam splitter 120 and the light valve 130 and be converted into the image light beam L2. SUMMARY OF THE INVENTION Corresponding to the above-described invention applied to an optical system, the optical system has better performance and higher efficiency. The present invention provides an optical system for providing an image beam comprising a light source, a beam splitting/combining device, and a light valve. The light source is used to provide a beam of light; the 7-way/combining device comprises a first polarizing beam splitter, a second polarizing beam splitter, a quarter wave plate (QWP) and a reflection benefit. The first polarizing beam splitter reflects the first beam of light from the source of light and the second of the bundle of rays from the source penetrates the first polarizing beam splitter. The second beam of light from the first polarizing beam splitter penetrates the second polarizing beam splitter and the quarter-wave plate, is reflected by the reflector, penetrates the quarter-wave plate, and is then polarized by the second Spectroscopic reflection. The light valve converts the first beam of light from the first polarizing beam splitter and the second beam of light from the second polarizing beam splitter into an image beam. According to an embodiment of the invention, the optical system described above further includes an analyzer which is disposed on the optical path of the image beam. In accordance with an embodiment of the invention, the reflector is a reflective layer and is plated on a quarter wave plate. According to an embodiment of the present invention, the first partial polarity S pole and the 1339315 HD-2007-0022-TW 25642 twf.doc/n are as described above. According to an embodiment of the present invention, the first bias is extremely p-polarized and the second bias is substantially S-polarized. The invention further provides an optical system for providing an image beam comprising a light source, a beam splitting/combining device and a light valve. The light source is used to provide a beam of light. The beam splitting/combining device comprises a first polarizing beam splitter, a second polarizing beam splitter, a half wave plate (four) fwaveplate (abbreviated as Hwp) and a reflector. • The second polarized beam splitter reflects the first beam of light from the source and the second beam of rays from the source penetrates the first polarizing beam splitter. The second beam of light from the first polarizing beam splitter penetrates the half wave plate. The second polarizing beam splitter reflects the second beam of light from the one-half wave plate. The light valve converts the first light beam reflected from the first-polarized mirror into a first image beam that penetrates the first polarization beam splitter, and converts the second light beam reflected from the second polarization beam splitter into And a second image beam that penetrates the second polarization beam splitter, wherein the first image beam combines with the second image beam to form an image beam. According to the present invention, the light device of the present invention further includes an analyzer </ RTI> disposed on the optical path of the image beam. According to the embodiment of the present invention, the first-to-bias s-polarity and the second-order bias are extremely ρ-polar. According to an embodiment of the present invention, the first-to-bias extreme p-polarity and the second-biased deviation are extremely s-polar. The present invention further provides an optical system for providing an image beam comprising a light source, a beam splitting/combining device, and a light valve. The light source is used to provide a beam of light. The beam splitting/combining device comprises a first-polarizing beam splitter, a second polarizing splitter HD-2007-0022-TW 25642 twf.doc/n light mirror, a quarter-wave plate, a first reflector and a second reflector. The first polarizing beam splitter reflects the first beam of light from the source and the second beam of light from the source penetrates the first polarizing beam splitter. The second polarizing beam splitter reflects the second beam of light from the first polarizing beam splitter. The first beam of light reflected from the first polarizing beam splitter will penetrate the quarter wave plate. The first reflector reflects the first beam of light from the quarter wave plate, wherein the first beam of light reflected by the first reflector penetrates the quarter wave plate and the first polarization beam splitter. The second reflector reflects the first beam of light that has passed through the first polarizing beam splitter, wherein the first beam of light reflected by the second reflector is reflected by the second polarizing beam splitter. The light valve converts the first light beam from the second polarizing beam splitter into a first image beam that penetrates the second polarizing beam splitter, and converts the second light beam from the second polarizing beam splitter into a penetrating first The second image beam of the dipolar polarization beam splitter, wherein the first image beam combines with the second image beam to form an image beam. According to an embodiment of the invention, the optical system further includes an analyzer </ RTI> disposed on the optical path of the image beam. According to an embodiment of the present invention, the first partial polarity is extremely s-polar and the first one is substantially P-polarized. In accordance with an embodiment of the present invention, the first bias is substantially p-polarized and the second bias is substantially s-polar. The present invention further provides an optical system for providing an image beam comprising a light source, a beam splitting/combining device, and a light valve. The light source is used to provide a beam of light. The beam t-off/combination H includes a first-polar pole split, a second polarized beam splitter, a half wave plate (Hwp) and a reflector. The first polarizing beam splitter reflects the first beam of light from the source and the second beam of light from the source HD-2007-0022-TW 25642twf.doc/n penetrates the first polarizing beam splitter. The second polarizing beam splitter reflects the first beam of light from the first polarizing beam splitter. The light beam from the first polarizing beam splitter will penetrate the half wave plate. The reflector reflects a second beam of light from the one-half waveplate, wherein the second beam of light reflected from the reflector is reflected by the second polarizing beam splitter. The light valve converts the first light beam from the second polarizing beam splitter into a first image beam that penetrates the second polarizing beam splitter, and converts the second light beam from the second polarizing beam splitter into a penetrating first The second image beam of the dipolar polarization beam splitter, wherein the first image beam combines with the second image beam to form an image beam. According to an embodiment of the invention, the optical system further includes an analyzer disposed on the ray path of the image beam. According to the embodiment of the present invention, the first-to-bias s-polarity and the above-described two-bias are extremely p-polar. According to the embodiment of the present invention, the U is extremely p-polarized and the above-described second bias is extremely s-polar. As in the above embodiment of the invention, the first ray beam and the second ray are converted into image beams. Thereby, the actual light system of the present invention has better performance and higher efficiency. The above features and advantages of the present invention will be more apparent and understood, and the embodiments will be described in detail below. Embodiments The following description will be made with reference to the embodiments set forth in the drawings of the embodiments. The reference numerals of the phases HD-2007-0022-TW 25642 twf.doc/n used in the respective drawings are used to describe the same or similar parts. 2 is a diagram illustrating an optical system in accordance with an embodiment of the present invention. Referring to Figure 2, optical system 200 provides an image beam L40 that includes a light source 210, a beam splitting/combining device 22A, and a light value 230. The light source 210 provides an illumination beam L30 including a first ray bundle L32 having a first polarization D1 and a second ray bundle L34 having a second polarization D2, and the beam splitting/combining device 220 configuration On the ray path of the light beam L30. The beam splitting/combining device 220 includes a first polarizing beam splitter (PBS) 222, a second polarizing beam splitter 224, and a quarter wave plate (QWP) 226 and a reflector 228. . The first polarizing beam splitter 222 reflects a first beam of light from the source 210 having a first polarization D1 to the light valve 230 and a second beam of light from the source 210 having a second polarization D2. The second light beam L34 from the first polarizing beam splitter penetrates the second polarizing beam splitter 224 and the quarter wave plate 226' and is then reflected by the reflector 228. The second light beam L34 reflected from the reflector 228 is converted into a second light beam having a first polarization D1 after penetrating the quarter wave plate 226, and then reflected by the second polarization beam splitter 224 into the light valve. 230. The light valve 230 converts the first light beam L32 from the first polarizing beam splitter 222 into the first image light beam L42 and the second light beam L34 reflected from the second polarizing beam splitting mirror 224 into the second image light beam L44. The first image beam L42 and the second image beam L44 both have a second polarization D2, and the first image beam L42 and the second image beam L44 will each penetrate the first bias HD-2007-0022-TW 25642twf.doc/n The pole splitter 222 and the second polarizer beam splitter 224 combine the first image beam L42 and the second image beam L44 to form an image beam L40. The optical system 200 utilizes the second polarizing beam splitter 224 and the reflector 228' to cause not only the first light beam L32 converted into the image light beam L40, but also the second light beam L34 to be converted into the image light beam L40. Thereby, the optical system 200 has higher efficiency and better performance, thereby improving the image quality of the projector using the optical system 200. The optical system 200 can be applied to the projector 30A. FIG. 3 is a diagram illustrating a projector in accordance with an embodiment of the present invention. Referring to Fig. 3, the projector 3 has an optical system 200 and a projection lens 310. The projection lens 310 is disposed on the ray path of the image light beam L40 from the optical system 200. The projection lens 310 projects the image light beam L40 on a screen (not shown) to form an image (not shown). In addition, the optical system 200 may further include an analyzer 240 disposed on the ray path of the image beam and located between the first polarization beam splitter 222, the first polarization beam splitter 224, and the projection lens 310. The analyzer 240 further enhances the polarization of the image beam L40 to enhance the contrast of the image. The first polarizer D1 may be S-polarized, and the second bias D2 may be P-polarized. However, the first polarization D1 can also be p-biased, while the second polarization D2 can be S-polarized. The first and second polarizing beamsplitters 222 and 224 may be a wire mesh grid polarizer (wire_grid p〇iarizer, WGp for short), a thin film polarizer (thin-film polarizer (TFP), a polymer film polarizer (polymer- The film polarizer (PFP) is implemented in the form of a solid or a flat plate. The light valve 230 may be a reflective light valve, for example, 1339315 HD-2007-0022-TW 25642 twf.doc/n liquid crystal on silicon (LCOS). Additionally, reflector 228 and quarter wave plate 226 can be other devices that can be implemented. 4 is a diagram showing other embodiments of the optical system of FIG. 2. Referring to Fig. 4, the reflector 228 in the present embodiment may be a reflective layer and mineralized on the quarter wave plate 226. It is to be noted that the optical system 200 described above has disclosed embodiments of the present invention. However, the optical system can also be implemented in other ways. Several other implementations are disclosed below. It is important to note that the next embodiment will be similar to the embodiment described in Figure 2. And the same or similar reference numerals will be used for the following embodiments in the same or similar parts to the embodiment of Fig. 2. The other embodiments are different from the embodiment of Fig. 2 as described below. Figures 5, 6A through 6C and Figure 7 illustrate an optical system in accordance with an embodiment of the present invention. Referring to Fig. 5, the beam splitting/combining device 220a in the optical system 200a includes a first polarizing beam splitter 222, a second polarizing beam splitter 224, and a half wave plate (HWP) 226a. The first polarization beam splitter 222 reflects the first light beam L32 from the light source 210 having the first polarization D1 to the light valve 230 while transmitting the second light beam L34 from the light source 210 having the second polarization D2. The second ray bundle L34 from the first polarizing beam splitter 222 then penetrates the half wave plate 226a and is converted into a second ray bundle L34 having the first polarizer D1. The second polarizing beam splitter 224 reflects the second light beam L34 from the half wave plate 226a into the light valve 230. The first image beam L42 and the second image beam L44 both have a first polarization D2, and the first image beam L42 and the second image 12 1339315 HD-2007-0022-TW 25642twf.doc/n beam L44 will each penetrate the first A polarization beam splitter 222 and a second polarization beam splitter 224' combine the first image beam L42 and the second image beam L44 to form an image beam L40. 6A to 6C. Figure 6A is a perspective view of an optical system in accordance with an embodiment of the present invention. Figure 6B is a front elevational view of the optical system of Figure 6A. Figure 6C is a side view of the optical system of Figure 6A. 6A to 6C, the beam splitting/combining device 220b in the optical system 200b includes a first polarizing beam splitter 222, a second polarizing beam splitter 224, a quarter wave plate 226, a first reflector 228, and a first The second reflector 228". It is particularly noted that, for the sake of clarity, the quarter-wave plate 226 and the first reflector 228 in Fig. 6 are combined as one object. However, the 'quarter wave plate 226 and the first reflector 228, which may be separately disposed in the embodiment of Fig. 2. The first polarizing beam splitter 222 reflects the first light beam L32 from the light source 210 and having the first polarizer D1 while transmitting the light source 210 and a second light beam L34 having a second polarization D2. The second polarization beam splitter 224 reflects the second light beam L34 from the first polarization beam splitter 222 to the light valve 230. The first light beam L32 then penetrates The quarter wave plate 226, after being reflected by the first reflector 228', penetrates the quarter wave plate 226' again and is converted into a first light beam L32 having a second polarization £>2. The first ray beam] penetrates the first polarizing beam splitter 222 'is reflected by the second reflector 228", and is then Two polarizing beam splitter 224 is reflected to the light valve 230. The light valve 230 converts the first light beam L32 and the second light beam 134 from the second polarizing beam splitter 224 into a first image light beam L42 and a second image light beam L44, respectively. The first image beam L42 and the second image beam L44 each have a first polarization D1 that penetrates the second polarization split 13 1339315 HD-2007-0022-TW 25642 twf.doc/n mirror 224 and combines to form an image beam L4. Hey. In the present embodiment, the normalized vector V of the second polarizing beam splitter 224 is combined with the first polarizing beam splitter 222, the first reflector 228, the second reflector 228, and the quarter wave plate 226. The plane PL formed by the normalization vector (not shown) and the 'that is, the second polarization beam splitter 224 cannot be placed on the plane PL ' and the light path of the image beam can be perpendicular to the plane P1. In the embodiment of FIGS. 6A to 6C, the second polarization D2 of the first polarization beam splitter 222 may be an S pole, and the second polarization D2 of the second polarization beam splitter 224 may be P is extremely polar. On the other hand, the first polarization D1 of the first polarization beam splitter 222 may be a P-polarization 'other than that'. The first polarization D1 with respect to the second polarization beam splitter 224 may be an S-polarization. Referring to Fig. 7, the beam splitting/combining device 220c in the optical system 200c includes a dipole beam splitter 222, a dipole beam splitter 224, a bipolar wave plate 226c, and a reflector 228. The first polarization beam splitter 222 reflects the first light beam L32 from the light source 210 having the first polarization D1 while transmitting the second light beam L34 from the light source 210 having the second polarization D2. The first ray bundle L32 from the first polarization beam splitter 222 is then reflected by the second polarization beam splitter 224 to the light valve 340. The first light beam L34 from the first polarization beam splitter 222 penetrates the one-wave plate 226c and is converted into a second light beam L34 having the first polarization D1. The second ray bundle L34 is then reflected by the reflector 228 and reflected by the second polarization beam splitter 224 into the light valve 230. The light valve 230 converts the first light beam L32 and the second light beam L34 from the second polarizing beam splitter 224 into a first image light beam L42 and a 141339315 HD'20〇7-〇〇22-TW 25642twf. Doc/n Two image beam L44. The first image beam L42 and the second image beam L44 white have a second polarization D2 that penetrates the second polarization beam splitter 224 and combines to form an image beam L40. It should be noted that the optical system disclosed above can be applied to the projector in the same manner as in Fig. 2. In summary, the two polarized beams of light are converted into image beams, that is, the optical system of the above embodiment can utilize more rays than the conventional optical system. Therefore, the optical system of the above embodiment has high efficiency and better performance, and can improve the image quality projected by the projector using the optical system of the present invention. Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the present invention is defined by the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a diagram illustrating a conventional optical system. FIG. 1B is a diagram illustrating another conventional optical system. 2 is a diagram illustrating an optical system in accordance with an embodiment of the present invention. FIG. 3 is a diagram illustrating a projector in accordance with an embodiment of the present invention. 4 is a diagram illustrating another embodiment of the optical system of FIG. 2. Figures 5, 6A through 6C, and Figure 7 are diagrams illustrating an optical system in accordance with the present invention. Λ 15