200921160 九、發明說明： 【發明所屬之技術領域】 '本發明涉及一種光學元件，尤其涉及一種應用於液 晶投影機之偏振光轉換器及具有該偏振光轉換器之投影 系統。 【先前技術】 投影系統中一般利用偏振光轉換器（Polarization Conversion System，PCS)對光路方向進行偏振轉換，偏 振光轉換器包括一玻璃基板，玻璃基板内形成有與玻璃 基板表面呈一定方向傾斜之（一般傾斜45度）偏振分光 (Polarization Bean，PB)鑛膜。偏振光轉換器分為對稱式 與非對稱式兩種，一般利用玻璃基板四侧霧面進行定 位，使PB鍍膜斜面正確對位至入射光之位置。非對稱 式偏振光轉換器於製作時容易一體成型，於中心定位要 求較高時亦不會影響非對稱式偏振光轉換器之中心定位 準確性。200921160 IX. Description of the Invention: [Technical Field of the Invention] The present invention relates to an optical element, and more particularly to a polarization converter for a liquid crystal projector and a projection system having the same. [Prior Art] In a projection system, a polarization conversion is generally performed by a polarization converter (PCS). The polarization converter includes a glass substrate, and the glass substrate is formed to be inclined in a certain direction with the surface of the glass substrate. (Generally inclined 45 degrees) Polarization Bean (PB) mineral film. The polarized light converter is divided into two types: symmetric type and asymmetric type. Generally, the four sides of the glass substrate are used for positioning, so that the PB coating bevel is correctly aligned to the position of the incident light. The asymmetric polarization converter is easy to integrally form during fabrication, and does not affect the centering accuracy of the asymmetric polarization converter when the center positioning requirement is high.
V 然而，於對稱式偏振光轉換器中，一般利用兩玻璃 基板粘貼形成，兩玻璃基板内之偏振分光鍍膜轴為對稱 設置，若仍然依靠玻璃基板週邊之四侧霧面來進行定位， 於中心定位要求較高時，對稱式偏振光轉換器無法保證 PB鍍膜斜面正確對位到入射光之位置。因而四侧霧面對 位之準確度非常不穩定。若PB鍍膜斜面與入射光對位 不良，將嚴重影響通光效率。 【發明内容】 6 200921160 器及提供一種定位準確之偏振光轉換 啕政偏振先轉換器之投影系統。 二種偏振光轉換器，其用於使人射祕換為同一偏 述偏振光轉換器包括一第一玻璃基 …所述第一玻璃基板内形成有多個 π排狀第—偏振分紐膜斜面，所述第二玻璃 多個互相平行排列之第二偏振分光鏡膜斜 —4弟—玻璃基板與所述第二玻璃基板之間具有一 面及第一連接面，所述定位面與所述第一連接面 盘平面。所述第二玻璃基板藉由所述第一連接面 ”所述弟-玻璃基板相連接。所述定位面用於使所述多 ^弟―偏振分絲蘭面及料多個第二偏振分光鑛膜 斜面準確對位到入射光之位置。 、 、，一種投影系統，其包括—光源及—偏振光轉換器。 :斤述偏振光轉換|§包括—第—玻璃基板與—第二玻璃基 反。所述偏振光轉換器包括—第—玻璃基板與—第二玻 璃基板’所述第-玻璃基板内形成有多個互相平行排列 ，第—偏振分光制斜面，所述第二玻縣板内形成有 夕個互相平行排列之第二偏振分光鍍膜斜面。所述第— j璃基板與所述第二玻璃基板之間具有一定位面及一第 一連接面，所述定位面與所述第—連接面位於同—平 面。所述第二玻璃基板藉由所述第―連接面與所述第— 玻璃基板相連接。所収位面用於使所^個第一偏振 分光鍵膜斜面及所述多個第二偏振分光⑽斜面準確對 200921160 =到入射光之位置。光源之光線經所述偏振光轉換器之 多個第一偏振分光鍍膜斜面及多個第二偏振分光鍍膜斜 面後轉換為同一偏振方向之偏振光。 a,相較於先前技術，所述之偏振光轉換器及其應用之 ，影系統湘位於所述偏振光轉換m玻璃基板與 第二玻璃基板間相連之表面所形成之定位面進行定位，、 即定位面位於所述偏振光轉換器靠近中間位置，從而保 ，所述偏振光轉換器中心^位準碟。同時使偏振光轉換 益上各PB反射面正確對位到人射光之位置，提高了偏 振光轉換器之通光效率。 【實施方式】 _下面將結合附圖對本發明實施例作進一步之詳細 說明。 、 請一併參閱圖！及圖2，其為本發明第一實施例之 偏振先轉換器4〇。偏振光轉換器4〇包括—第一玻 ί-42個一第二玻璃基板44、形成於第-破璃基板42二 一二=相平行排列之第一仙鑛膜斜面仏、形成於第 一玻璃基板44内之多個互相平行排列之第二 面44a及多個半波片46。 又、 本實施例中，玻璃基板42設有四 面仏、玻璃基板44設有四 PB鍍膜斜 &個Μ „ 们弟一 ΡΒ鍍膜斜面44a， 母個第一 PB鍍膜斜面42a 胺钮而^ 卩幻万向與母個第二PB鍍 膜斜面44a之排列方向軸對稱設置。 〇又 設有半波片46，本實施例中，*置有 換益40 頁财°又置有四個半波片46。其 200921160 中半波片46間隔粘貼於相鄰之第一 PB鍍膜斜面42a間 之玻璃基板42之表面425及相鄰之第二PB鍍膜斜面 44a間之玻璃基板44之表面445。優選地，每個第一 PB 鍍膜斜面42a均與第一玻璃基板42表面425傾斜45度 設置。每個第二PB鍍膜斜面44a均與第二玻璃基板44 表面445傾斜45度設置。 第一玻璃基板42包括一連接面424、一第一定位面 426及一第二定位面428。所述連接面424、第一定位面 426及第二定位面428位於同一側之同一平面。第二玻 璃基板44藉由所述第一玻璃基板42之連接面424與所 述第一玻璃基板42相連接。本實施例中，採用膠合方式 相連接。第一定位面426與第二定位面428沿連接面中 心424轴對稱。 利用四側霧面進行定位時，未對偏振光轉換器40 之第一玻璃基板42與第二玻璃基板44靠近中間相連之 表面進行定位，從而造成各第一 PB鍍膜斜面44a及第 二PB鍍膜斜面44b無法準確對位到入射光之位置，無 法使偏振光轉換器40將自然光全部轉變為s(s-polarized light)偏振光。於製作偏振光轉換器40時，利用PB鍍膜 斜面排列方向不同及寬度不同之第一玻璃基板42與第 二玻璃基板44相粘貼合成以使寬度較大之第一玻璃基 板42露出第一定位面426及第二定位面428。第一定位 面426及第二定位面428位於第一玻璃基板42與第二玻 璃基板44相連之表面，即位於靠近偏振光轉換器40中 200921160 〜位置。利用第一定位面426及第二定位面428進行定 位’能使第一玻璃基板42與第二玻璃基板44之中心定 位準格，從而保證第一 PB鍍膜斜面44a及第二pb鍍膜 斜面44b準確對位到入射光之位置，進而使半波片46 能準確對位到入射光之位置。從而使偏振光轉換器4〇 透射自然光中之p偏振光（p_p〇larized light)、反射s偏 振光。p偏振光自偏振光轉換器40透射後進入半波片 46並轉變為S偏振光射出。S偏振光於偏振光轉換器 4〇内經兩次反射後由偏振光轉換器4〇未設半波片之 部分射出，從而將入射之自然光全部轉變為s偏振光。 凊參閱圖3，其為本發明第二實施例之偏振光轉換 时80所述偏振光轉換器80包括一第一玻璃基板82、 =第二玻璃基板84、多個形成於第一玻璃基板82内之 第一 PB鍍膜斜面82a、多個形成於第二玻璃基板84内 之夕個第二PB鍍膜斜面84a、多個半波片86及一棱鏡V However, in the symmetrical polarization converter, it is generally formed by bonding two glass substrates, and the polarization beam splitting coating axes in the two glass substrates are symmetrically arranged, and if they are still positioned by the four sides of the glass substrate, they are positioned at the center. When the positioning requirements are high, the symmetrical polarization converter cannot guarantee the correct alignment of the PB coating bevel to the position of the incident light. Therefore, the accuracy of the four sides facing the fog is very unstable. If the PB coating bevel is in poor alignment with the incident light, the light passing efficiency will be seriously affected. SUMMARY OF THE INVENTION 6 200921160 and provide a positioning system for accurate polarization conversion of the polarization first converter. Two kinds of polarized light converters for converting a human lens to the same parametric polarization converter include a first glass substrate, wherein the first glass substrate is formed with a plurality of π-plated first-polarization splitting films a second surface of the second glass, the second polarizing beam splitter film is arranged in parallel with each other, and has a side and a first connecting surface between the glass substrate and the second glass substrate, the positioning surface and the positioning surface The first connection faceplate plane. The second glass substrate is connected by the first connecting surface “the glass-glass substrate. The positioning surface is used to make the multi-different-polarized sifting surface and the plurality of second polarizing beams. The bevel of the ore film is accurately aligned to the position of the incident light. A projection system includes a light source and a polarization converter. The polarization conversion is performed. § includes a - glass substrate and a second glass substrate. The polarizing light converter comprises: a first glass substrate and a second glass substrate, wherein the first glass substrate is formed with a plurality of mutually parallel arranged, a first polarization splitting slope, and the second glass plate Forming a second polarization splitting coating bevel arranged in parallel with each other, wherein the first glass substrate and the second glass substrate have a positioning surface and a first connecting surface, the positioning surface and the positioning surface The first connecting surface is located at the same plane. The second glass substrate is connected to the first glass substrate by the first connecting surface, and the receiving surface is used for making the first polarizing light splitting film bevel and The plurality of second polarization splitting lights (10) are oblique Accurately to 200921160 = position to the incident light. The light of the light source is converted into polarized light of the same polarization direction by a plurality of first polarization beam splitting coating bevels and a plurality of second polarization beam splitting coating bevels of the polarization converter. Compared with the prior art, the polarized light converter and the application thereof are located on the positioning surface formed by the surface connected between the polarized light conversion m glass substrate and the second glass substrate for positioning, that is, positioning The surface is located near the intermediate position of the polarized light converter, thereby ensuring that the center of the polarized light converter is at the same time. At the same time, the polarized light is converted into a position where the respective PB reflecting surfaces are correctly aligned to the position of the human light, thereby improving the polarization. The light-transmission efficiency of the optical converter. [Embodiment] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Please refer to FIG. 2 and FIG. 2, which is the polarization of the first embodiment of the present invention. The converter 4A includes a first glass substrate, a second glass substrate 44, and a first glass film formed on the first glass substrate 42. The beveled surface is formed in a plurality of second faces 44a and a plurality of half-wave plates 46 arranged in parallel with each other in the first glass substrate 44. In the embodiment, the glass substrate 42 is provided with a four-sided crucible and the glass substrate 44 is provided. Four PB coatings are inclined & Μ „ 们 ΡΒ 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们 们Further, a half-wave plate 46 is provided. In this embodiment, * is provided with a change of 40 pages and four half-wave plates 46 are provided. The mid-wave plate 46 of the 200921160 is interposed between the surface 425 of the glass substrate 42 between the adjacent first PB coating bevels 42a and the surface 445 of the glass substrate 44 between the adjacent second PB coating bevels 44a. Preferably, each of the first PB coating bevels 42a is disposed at an angle of 45 degrees to the surface 425 of the first glass substrate 42. Each of the second PB coating bevels 44a is disposed at an angle of 45 degrees to the surface 445 of the second glass substrate 44. The first glass substrate 42 includes a connecting surface 424, a first positioning surface 426 and a second positioning surface 428. The connecting surface 424, the first positioning surface 426 and the second positioning surface 428 are located on the same plane on the same side. The second glass substrate 44 is connected to the first glass substrate 42 via a connection surface 424 of the first glass substrate 42. In this embodiment, the bonding is performed by gluing. The first locating surface 426 and the second locating surface 428 are axisymmetric along the center of the connecting surface 424. When the four-side matte surface is used for positioning, the first glass substrate 42 of the polarization converter 40 and the second glass substrate 44 are not positioned adjacent to the intermediate surface, thereby causing the first PB coating bevel 44a and the second PB coating. The slope 44b cannot be accurately aligned to the position of the incident light, and the polarization converter 40 cannot be made to convert all of the natural light into s-polarized light. When the polarization converter 40 is manufactured, the first glass substrate 42 having different PW plating slopes and different widths and the second glass substrate 44 are bonded and combined to expose the first glass substrate 42 having a larger width to the first positioning surface. 426 and second positioning surface 428. The first positioning surface 426 and the second positioning surface 428 are located on the surface of the first glass substrate 42 connected to the second glass substrate 44, that is, near the position of the polarization converter 40 in the 200921160~ position. The positioning of the first positioning surface 426 and the second positioning surface 428 can be used to position the center of the first glass substrate 42 and the second glass substrate 44, thereby ensuring that the first PB coating bevel 44a and the second pb coating bevel 44b are accurate. The position is aligned to the incident light, so that the half-wave plate 46 can be accurately aligned to the position of the incident light. Thereby, the polarization converter 4 transmits the p-polarized light (p_p〇larized light) and the reflected s-polarized light in the natural light. The p-polarized light is transmitted from the polarization converter 40, enters the half-wave plate 46, and is converted into S-polarized light. The S-polarized light is reflected twice by the polarization converter 4 后 and then emitted by the polarization converter 4 〇 without the half-wave plate, thereby converting the incident natural light into s-polarized light. Referring to FIG. 3, in the polarization conversion of the second embodiment of the present invention, the polarization converter 80 includes a first glass substrate 82, a second glass substrate 84, and a plurality of first glass substrates 82. a first PB coating bevel 82a, a plurality of second PB coating bevels 84a formed in the second glass substrate 84, a plurality of half-wave plates 86 and a prism
87 〇87 〇
本實施例中，第一玻璃基板82内設置四個第一 PB 鍍膜斜面82a，每個第一 PB鍍膜斜面82a互相平行排 歹J第一玻璃基板84内設置四個第二面pB鑛膜8如， 每個第一 PB鍍膜斜面84a互相平行排列。每個第一 pB 鍍膜斜面82a分別與每個第二？6鍍膜斜面8乜關於棱 鏡87之軸對稱設置。 偏振光轉換器80設置有多個半波片％，本實施例 中，設置四個半波片86。半波片86間隔粘貼於相鄰之 200921160 第一 PB鍍膜斜面84a間之第一玻璃基板82之表面825 及相鄰之第二PB鍍膜斜面84a間之第二玻璃基板84之 表面845。 第一玻璃基板82包括一第一連接面852、一第一定 位面882及一第二定位面884。所述第一定位面882及 第二定位面884沿第一連接面852對稱設置。第二玻璃 基板84包括一第二連接面854、一第三定位面886及一 第四定位面888,所述第三定位面886及第四定位面888 沿第二連接面854對稱設置。 所述棱鏡87之兩個表面分別與第一連接面852及 第二連接面854相膠合以使第一玻璃基板82與第二玻璃 基板84相連接形成偏振光轉換器80。可以理解，棱鏡 87之高度不影響偏振光轉換器80之光線偏振方向即 可，棱鏡87之高度可與偏振光轉換器80之高度相同， 也可不相同。本實施例中，棱鏡87之高度與偏振光轉換 器80之高度相同。 " 第一定位面882、第二定位面884、第三定位面886 及第四定位面888位於第一玻璃基板82與第二玻璃基板 84藉由棱鏡87相連之各表面，即位於偏振光轉換器80 之靠近中心位置，能使第一玻璃基板82與第二玻璃基板 84之中心定位準確。從而保證各第一 PB鍍膜斜面84a 及第二PB锻膜斜面84b準確對位到入射光之位置，保 證中心位置定位之準確性，進而使半波片86能準確對位 到入射光之位置。從而將入射之自然光全部轉變為s偏 11 200921160 振光。 請參閱圖4，其為一投影系統100，其具有第一實 施例之偏振光轉換器40。所述投影系統100還包括一光 源 10、一紫外-紅外（Ultraviolet-Infrared，UV-IR)遽鏡 20及兩微鏡陣列22。所述UV-IR濾鏡20、所述兩微鏡 陣列22及所述偏振光轉換器40依次沿光源10之光線光 路方向設置。優選地，可於兩微鏡陣列22間設置一反光 鏡24改變光路，縮小投影系統100之尺寸。另外，投影 系統10 0還包括沿偏振光轉換器4 0之出射光路方向上依 次設置之積分柱、成像裝置及投影鏡頭等（圖中均未示）。 UV-IR濾鏡20濾掉光源10射出之光線中之紫外光 及紅外光，避免紫外光及紅外光降低成像品質。 光源10之光線從光源射出後，經UV-IR濾鏡20濾 掉光線中之紫外光與紅外光，然後光線經兩微鏡陣列 22、所述反光鏡24不連續地會聚於偏振光轉換器40之 第一玻璃基板42。利用第一玻璃基板42與第二玻璃基 板44相連之表面所形成之第一定位面426及第二定位面 428，即靠近偏振光轉換器40之中間位置來進行定位。 能使各第一 PB鍍膜斜面42a及第二PB鍍膜斜面44a準 確對位到入射光之位置，進而使半波片46能準確對位到 入射光之位置，使偏振光轉換器40將入射之自然光全部 轉變為s偏振光。 可以理解，所述投影系統100中之偏振光轉換器40 也可為第二實施例之偏振光轉換器80。利用偏振光轉換 12 200921160 器80之第一定位面882、第二定位面884、第三定位面 886及第四定位面888使每個半波片86及每個第一 PB .鍍膜斜面82a及每個第二PB鍍膜斜面84a之反射面正 確對位到入射光之位置，使偏振光轉換器80將入射之自 然光全部轉變為s偏振光。 上述實施例中，每一投影系統之偏振光轉換器利用 靠近各偏振光轉換器之中間位置之定位面進行定位，從 而保證所述偏振光轉換器中心定位準確，使偏振光轉換 器上各半波片及PB反射面正確對位到入射光之位置， 提高了偏振光轉換器之通光效率。 綜上所述，本發明確已符合發明專利要件，爰依法提出 專利申請。惟，以上所述者僅為本發明之較佳實施方式，舉 凡熟悉本案技藝之人士，於援依本案發明精神所作之等效修 飾或變化，皆應包含於以下之申請專利範圍内。 【圖式簡單說明】 圖1為本發明第一實施例之偏振光轉換器之立體示 意圖。 圖2為圖1之偏振光轉換器之主視圖。 圖3為本發明第二實施例之偏振光轉換器之立體示 意圖。 圖4為應用圖1之偏振光轉換器之投影系統之示意 圖。 【主要組件符號說明】 偏振光轉換器 40、80 第一玻璃基板 42、82 13 200921160 第一 PB鍵膜斜面42a、 82a 連接面 424 表面 425、 445 第一定位面 426、 882 第二定位面 428、 884 第二玻璃基板 44、84 第二PB鍍膜斜面44a、 84a 第一連接面 852 半波片 46、 86 第二連接面 854 第三定位面 886 第四定位面 888 棱鏡 87 投影糸統 100 光源 10 UV-IR濾鏡 20 微鏡陣列 22 反光鏡 24 14In this embodiment, four first PB coating bevels 82a are disposed in the first glass substrate 82, and each of the first PB coating bevels 82a is parallel to each other. J is disposed in the first glass substrate 84. For example, each of the first PB plating bevels 84a is arranged in parallel with each other. Each first pB coated bevel 82a is associated with each second? 6 coated bevel 8 乜 is arranged symmetrically about the prism 87. The polarization converter 80 is provided with a plurality of half-wave plates %. In the present embodiment, four half-wave plates 86 are provided. The half-wave plate 86 is affixed to the surface 845 of the first glass substrate 82 between the adjacent first 21st PB coated bevel 84a and the surface 845 of the second glass substrate 84 between the adjacent second PB coated bevels 84a. The first glass substrate 82 includes a first connecting surface 852, a first positioning surface 882 and a second positioning surface 884. The first positioning surface 882 and the second positioning surface 884 are symmetrically disposed along the first connecting surface 852. The second glass substrate 84 includes a second connecting surface 854, a third positioning surface 886 and a fourth positioning surface 888. The third positioning surface 886 and the fourth positioning surface 888 are symmetrically disposed along the second connecting surface 854. The two surfaces of the prism 87 are respectively glued to the first connecting surface 852 and the second connecting surface 854 to connect the first glass substrate 82 and the second glass substrate 84 to form a polarization converter 80. It can be understood that the height of the prism 87 does not affect the polarization direction of the light of the polarization converter 80. The height of the prism 87 may be the same as or different from the height of the polarization converter 80. In the present embodiment, the height of the prism 87 is the same as the height of the polarization converter 80. " The first positioning surface 882, the second positioning surface 884, the third positioning surface 886 and the fourth positioning surface 888 are located on the respective surfaces of the first glass substrate 82 and the second glass substrate 84 connected by the prism 87, that is, at the polarized light The near center position of the transducer 80 enables accurate positioning of the centers of the first glass substrate 82 and the second glass substrate 84. Therefore, the first PB coating bevel 84a and the second PB forging film 84b are accurately aligned to the position of the incident light, thereby ensuring the accuracy of the center position positioning, thereby enabling the half wave plate 86 to accurately align to the position of the incident light. Thus, all incident natural light is converted into s-polarity 11 200921160 illuminating. Referring to Figure 4, there is a projection system 100 having a polarization converter 40 of the first embodiment. The projection system 100 further includes a light source 10, an ultraviolet-infrared (Infrared-infrared) (UV-IR) mirror 20, and two micro mirror arrays 22. The UV-IR filter 20, the two micromirror arrays 22, and the polarization converter 40 are sequentially disposed along the light path of the light source 10. Preferably, a mirror 24 is disposed between the two micromirror arrays 22 to change the optical path to reduce the size of the projection system 100. Further, the projection system 100 further includes an integrating column, an imaging device, a projection lens, and the like (not shown) which are disposed in the direction along the outgoing light path of the polarization converter 40. The UV-IR filter 20 filters out the ultraviolet light and the infrared light in the light emitted from the light source 10 to prevent the ultraviolet light and the infrared light from degrading the image quality. After the light of the light source 10 is emitted from the light source, the ultraviolet light and the infrared light in the light are filtered by the UV-IR filter 20, and then the light is continually concentrated on the polarization converter through the two micromirror arrays 22 and the mirror 24. The first glass substrate 42 of 40. The first positioning surface 426 and the second positioning surface 428 formed by the surface of the first glass substrate 42 connected to the second glass substrate 44 are positioned adjacent to the intermediate position of the polarization converter 40. The first PB coating bevel 42a and the second PB coating bevel 44a can be accurately aligned to the position of the incident light, so that the half-wave plate 46 can be accurately aligned to the position of the incident light, so that the polarization converter 40 will be incident. Natural light is all converted into s-polarized light. It can be understood that the polarization converter 40 in the projection system 100 can also be the polarization converter 80 of the second embodiment. The first positioning surface 882, the second positioning surface 884, the third positioning surface 886 and the fourth positioning surface 888 of the polarized light conversion 12 200921160 80 are used to make each half wave plate 86 and each of the first PB coating bevels 82a and The reflective surface of each of the second PB coating bevels 84a is correctly aligned to the position of the incident light, causing the polarization converter 80 to convert all of the incident natural light into s-polarized light. In the above embodiment, the polarization converter of each projection system is positioned by using the positioning surface near the intermediate position of each polarization converter, thereby ensuring accurate positioning of the center of the polarization converter, and making the polarization converters The wave plate and the PB reflecting surface are correctly aligned to the position of the incident light, which improves the light-passing efficiency of the polarization converter. In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art of the present invention should be included in the following claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing a polarization converter according to a first embodiment of the present invention. 2 is a front elevational view of the polarization converter of FIG. 1. Fig. 3 is a perspective view showing a polarization converter according to a second embodiment of the present invention. 4 is a schematic view of a projection system to which the polarization converter of FIG. 1 is applied. [Main component symbol description] Polarization converter 40, 80 First glass substrate 42, 82 13 200921160 First PB key film bevel 42a, 82a Connection surface 424 Surface 425, 445 First positioning surface 426, 882 Second positioning surface 428 884 second glass substrate 44, 84 second PB coating bevel 44a, 84a first connection surface 852 half wave plate 46, 86 second connection surface 854 third positioning surface 886 fourth positioning surface 888 prism 87 projection system 100 light source 10 UV-IR filter 20 micro mirror array 22 mirror 24 14