200525433 九、發明說明： 【發明所屬之技術領域】 相關申請案之交互參照 吴國專利申請案第1〇/759,646號，申請日2004年1月16 5日名稱「位置測定與移動追蹤」，申請人Xie等人，讓與 本案之相同受讓人，以引用方式併入此處。 發明領域 概略言之，本發明係關於光學系統。特別，本發明係 關於使用干涉測量技術之光學式追蹤一目標。 10【先前技術】 發明背景 已經發展出多種系統及裝置讓資料可輸入電腦系統， 且致能操作該電腦系統之巡航/游標控制。電腦系統的使用 大量成長係與此等系統及裝置的進展有關。 15 此等系統及裝置典型利用若干技術之一。此等技術例 如包括機械執跡球、加速偵測、光學影像校正、雷射斑點 圖案分析、及強度偵測。也可使用其它技術。 雖然此等系統及裝置的改良可提升電腦系統的利用性 ，但此等系統及裝置實作技術之若干缺陷仍然持續限制此 20等系統及裝置可能達成的效果。舉例言之解析度有限之技 術造成電腦系統使用上的妨礙。此外若干此等系統之回應 時間缓慢。而其它技術只月b用於特殊表面類髮。此外右干 技術出現電力耗用問題。最後若干技術實作上對系統或裝 置要求的尺寸皆屬其缺點。 200525433 除了此等缺點外，其它問題關聯此等既有技術。通常 此等既有技術限於二維巡航/游標控制與相對座標追蹤(例 如位置的改變）。換言之物件位置的改變係於二維空間追 蹤，而非該物件的絕對位置（例如目前位置）。相對座产 限制此等系統及裝置用於例如需要絕對位晉；έ ^ 氧災縱之手窝 入等應用用途。總而言之，現有技術有嚴重 输 王听難以克肫u 限制。 的 【發明内容】 發明概要 10200525433 IX. Description of the invention: [Technical field to which the invention belongs] Cross-references to related applications refer to Wu Guo Patent Application No. 10 / 759,646, filed on January 16th, 2004 under the name "Position Measurement and Movement Tracking", application Xie et al., The same assignee as this case, are hereby incorporated by reference. FIELD OF THE INVENTION The present invention relates generally to optical systems. In particular, the invention relates to optically tracking a target using interferometric techniques. 10 [Prior Art] Background of the Invention Various systems and devices have been developed to allow data to be entered into a computer system and enable cruise / cursor control of the computer system. The use of computer systems has grown exponentially with the progress of these systems and devices. 15 These systems and devices typically utilize one of several technologies. These technologies include, for example, mechanical trackballs, acceleration detection, optical image correction, laser speckle pattern analysis, and intensity detection. Other techniques can also be used. Although improvements to these systems and devices can improve the usability of computer systems, certain shortcomings in the implementation of these systems and devices continue to limit the effects that these 20 systems and devices may achieve. For example, technologies with limited resolutions hinder the use of computer systems. In addition, the response time of some of these systems is slow. Other technologies are only used for special surface hair. In addition, the right-hand technology has a power consumption problem. The last few technical implementations require the size of the system or device to be their disadvantages. 200525433 In addition to these disadvantages, other issues are related to these existing technologies. Usually these existing technologies are limited to two-dimensional cruise / cursor control and relative coordinate tracking (such as position changes). In other words, the position of the object is changed in two-dimensional space tracking, rather than the absolute position of the object (such as the current position). Relative systems limit the use of these systems and devices for applications such as those requiring absolute advancement; All in all, the existing technology has serious limitations. [Summary of the Invention] Summary of the Invention 10
揭示一種使用干涉測量技術來以光學式、自ρ 他目；I：辱^ 15Reveals an optical, self-identifying method using interferometry; I: shame ^ 15
方法及系統。一種光學位置追蹤系統包含一 一光束產生一入射光束及一參考光束。此外铸光風彳/、由 蹤系統進一步包含一光束轉向裝置供掃拂該入:位薏追 一角度範圍，來造成入射光束由一目標反射，、光束通埯 束之反射被導向來干涉該參考光束俾形成〜干=4入射光 外，該光學位置追蹤系統致能使用干涉測量枝彳 =光束。此 射光束與干涉光束之角度值來測定該目標位置命，利用入 係依據反射決疋。若光束有複數個波長，由於 角夜值 多個波長，或於一段時間間隔有多重波長，j同時存在有 20標之絕對位置。若該光束有單一波長 貝11可測定姨目 相對位置。 ' ^定該目榡之 圖式簡單說明 附圖係結合於本說明書且構成本說明書之立 例說明根據本發明之具體例，連同其說明=之一部分，舉 …用來解釋根據太 6 200525433 發明之具體例之原理。 第1圖顯示根據本發明之具體例之系統，顯示一種光學 位置追縱糸統。 第2圖顯示根據本發明之具體例，一種用於追蹤目標之 5 相對位置之光學位置追蹤系統。 第3圖顯示根據本發明之具體例，由第2圖之光學位置 追蹤系統測得一目標之相對位置。 第4圖顯示根據本發明之具體例，由第2圖之偵測器回 應於干涉光束所產生之一信號。 10 第5圖顯示根據本發明之具體例，一種用於追蹤目標之 絕對位置之光學位置追蹤系統。 第6圖顯示根據本發明之具體例，由第5圖之光學位置 追蹤系統測得一目標之絕對位置。 第7圖顯示根據本發明之具體例，由第5圖之偵測器回 15 應於干涉光束所產生之多個信號。 第8A圖顯示根據本發明之具體例，光束之圓形截面。 第8B圖顯示根據本發明之具體例，光束之橢圓截面。 第9圖顯示根據本發明之具體例，以有限掃拂模操作之 第2圖光學位置追縱糸統。 20 第10圖為一流程圖，顯示根據本發明之具體例一種光 學追蹤一目標之方法。 【實施方式】 較佳實施例之詳細說明 現在將說明根據本發明之具體例之細節，其範例舉例 200525433 說明於附圖。雖然本發明將結合此等具體例做說明，但須 了解絕非意圖囿限本發明於該等具體例。相反地，本發明 意圖涵蓋如隨附之申請專利範圍界定之於本發明之精髓及 範圍内之變化例、修改例及相當例。此外於後文根據本發 5 明之具體例之細節說明，陳述多種特定細郎俾供徹底了解 本發明。 於根據本發明之具體例中，一種光學位置追蹤系統包 含一光束產生器來產生一光束，以及一光學裝置來由該光 束產生一入射光束及一參考光束。此外該光學位置追蹤系 10 統進一步包括一光束轉向裝置供掃拂該入射光束通過一定 角度範圍，且供導引該入射光束之反射來干涉該參考光束 ，當該入射光束由一目標反射時可形成一干涉光束。該入 射光束之反射包含一反射光束。此外，該光學位置追蹤系 統進一步包含一偵測器供偵測該干涉光束，以及_處理單 15元供當該目標反射入射光束、及干涉光束其提供與該目標 之距離時，使用干涉測量技術、以及包括人射光束角度: 之資料來決定目標位置。若光束有複數個波長，由於^時 存在有此等波長或於一段有多重波長之時間間P(l 定該目標之絕對位置。若該光束有罩—波長，則⑽定該 20目標之相對位置。 ~ 第1圖顯示根據本發明之具體例之系統刚，顯示光與 位置追縱系統20。系統100包括電腦系統5〇及光學位置追二 系統20。電腦系統50有一顯示器60。 ^攸 根據本發明之本具體例中，當目標騰二維空間移動 200525433 5 10 時:光學位置追縱系㈣追縱目㈣之位置。特別位置追 知系統20利用至少—光束如掃拂通過二維空間的—角度範 圍95。當目標_前後左右移動或於光束_作之二二空 間内部以任-餘合移_，該目標可反射光物。光束 9〇之反射包含反射狀光束8G，光束啊㈣追縱系統2〇 接收及處理來追蹤目標1〇之位置。 目標1〇可為任—型物件。例如目標1G可為滑鼠型裝置 、光筆、觸控螢幕輸人型裝置、手指等。目標ig之後反射 面可提升光學位置追縱系統2G追縱目標1()移動的能力。若 目標10有足夠反射性質，則可能不需要後反射面。 由光學位置追蹤系統20藉由產生對應於目標1〇位置之 位置資料來追蹤的目標U)之移動可利用來將資料輸入（例 統50之游標。 於本發明之另一具體例，光學位置追蹤系統2〇整合顯 示的60提供當目標1〇繞行顯示器6〇表面時之觸控螢幕功能 。此項實作比較先前技術之觸控螢幕實作成本更低且較不 複雜。 結構(相對位置追蹤具體例） 參照第2圖，顯示根據本發明之具體例，用於追蹤目標 2〇5相對位置之光學位置追蹤系統2〇〇之視圖。後文討論將 始於根據本發明之具體例之實體結構說明。此項討論接著 為說明根據本發明之具體例之操作。 參照根據本發明之具體例之實體結構，第2圖顯示根據 200525433 本發明之具體例，用於追蹤目標205相對位置之光學位置追 蹤系統200之視圖。相對位置係於極性座標測定，而「相對 位置」表示目標205位置相對於先前位置之變化。如第2圖 所示，光學位置追蹤系統200有一光束產生器21〇、一光學 5裝置260、一鏡270、一光束轉向裝置230、一偵測器240、 一聚焦透鏡250及一處理單元220。要言之，目標2〇5相對於 光束轉向裝置230之角度關係係結合偵測器240測定。此外 ，目標205與光束轉向裝置230之相對距離係使用干涉測量 技術測定，該技術仰賴由來自目標2〇5之反射光束286與參 10考光束282干涉所形成之干涉光束250。干涉光束250形成的 原因係反射光束286及參考光束282係沿差異長度路徑傳播 。如此當參考光束282與反射光束286組合時(例如干涉光束 250)，其形成亮暗條紋之干涉圖案，干涉圖案㈣測器24〇 接收，§路徑長度差異改變時，亮暗條紋位移 。因此目標 205之相對位置係由目標2〇5之此種角度關係、以及距離目 標205之相對距離表示。 光束產生。。210產生光束28〇。光束產生器21〇包括光源 212來產生光束280。光束挪為相干性，且具有單一波長入 。而光束產生器210有準直透鏡214。 2〇於根據本發明之—具體例，光源(例如光源212)可基於 低成本LED(發光二極體)技術。於本發明之另一具體例光 源係基於V C S E L (垂直腔表面發射雷射）技術於根據本發明 之又另-具體例，光源可基於具有適當準直能力之低成本 白熱技術。根據本發明之又另—具體例，光源可基於高功 10 200525433 率基於稀土元素之雷射。基於稀土元素之雷射例如包括 Nd-YAG(鈥釔鋁石榴石）雷射及脈衝式铒雷射。高功率基於 稀土之雷射可用於當目標205與偵測器之間距及吸收需要 較高光學功率時。 5 光學裝置26〇使用光束280來產生入射光束284及參考 光束282。於根據本發明之具體例，光學裝置260為分束器 260 ° 仍然參照第2圖，光束轉向裝置23〇掃拂入射光束284 通過角範圍290。為了說明藉光束轉向裝置23〇造成入射光 10束284之掃拂移動，第2圖顯示入射光束284於多個角度位置 (例如284A-284E)。此外，追縱入射光束284相對於目標205 及光束轉向裝置230之角度。此點舉例說明於第3圖其細節 討論如後。 光束轉向裝置230可為任何類型光束轉向裝置。於根據 15本發明之一具體例，光束轉向裝置為MEMS(微機電系統） 馬達光束轉向裝置。於根據本發明之另一具體例，光束轉 向裝置為電流計光束轉向裝置。於根據本發明之又另一具 體例，光束轉向裝置為聲-光束轉向裝置。於根據本發明之 另一具體例，光束轉向裝置為電_光束轉向裝置。於根據本 20發明之又另一具體例，光束轉向裝置為光柵結構光束轉向 裝置。於根據本發明之另一具體例，光束轉向裝置為全像 結構光束轉向裝置。於根據本發明之另一具體例，光束轉 向裝置為掃描鏡光束轉向裝置。使用MEMS處理可實質達 成成本的節省與尺寸的縮小。 200525433 如第2圖所示，目標205包括後反射面207來反射入射光 束284 °「後反射」一詞表示入射光束係於相對於入射光束 之平行方向反射之性質。後反射面207可以任一種方式實作 ’例如後反射膠帶、後反射塗料或任何其它耦合至目標表 5面之後反射材料。如前文說明，目標205可為任一型物件。 例如目標205可為滑鼠型裝置、光筆、觸控螢幕輸入型裝置 、手指等。若目標205有充分反射性質，則只要目標205可 於相對於入射光束平行方向反射入射光束，則可無須後反 射面。舉例言之，於寫入端帶有後反射面之辦公室光筆的 10移動可被追縱，且將該辦公室光筆的移動用作為電腦系統 之游標控制。 此外’處理單元220係耦合至光束轉向裝置230、偵測 器240及光束產生器21〇。處理單元22〇係經由使用多項資料 及干涉測量技術來決定目標2〇5之相對位置。 15 操作（相對位置追蹤具體例） 後文讨論說明根據本發明之操作細節。 參照第2圖，光學位置追蹤系統2〇〇之操作進行如後。 光源212產生光束280。光束280通過準直透鏡214，準直透 鏡214準直光束280。於通過準直透鏡214後，光束28〇朝向 20分束器260前進。分束器26〇使用光束280來產生入射光束 284及參考光束282。參考光束282被導引朝向鏡270，鏡反 射參考光束282朝向分束器260，然後送至偵測器24〇。 此外，入射光束284被導引朝向光束轉向裝置230。光 束轉向裝置230掃拂入射光束284通過角度範圍29〇，故入射 12 200525433 光束284出現於各個角度位置（例如284A—284E)。此處箭頭 235A及235B顯示光束轉向裝置230移動，讓入射光束284掃 拂通過角度範圍290。 當目標205之後反射面207反射入射光束284(例如284C) 5日守’入射光束284C之反射係朝向光束轉向裝置230反射。入 射光束284C之反射包含反射光束286。光束轉向裝置230導 引反射光束286至分束器260，來與參考光束282干涉，而形 成干涉光束285。干涉光束285通過聚焦透鏡250，聚焦透鏡 250聚焦干涉光束285，且到達偵測器240。偵測器240偵測 10干涉光束285，指示處理單元220，目標205已經被定位，故 處理單元220記錄入射光束284C之目前角度（例如第3圖之 角A)。於根據本發明之一具體例，處理單元220追蹤入射光 束284由光束轉向裝置230掃拂之角度。 偵測器240偵測干涉光束285，其包含反射光束286及參 15考光束282。處理單元220使用干涉測量技術決定由光束轉向 裝置230至目標205之相對距離(例如第3圖之相對距離ΔΚ)。 第3圖顯示根據本發明之具體例，由第2圖之光學位置 追蹤系統200測定目標2〇5之相對位置τ。如第3圖所示，光 束轉向裝置230之位置S為已知。角Α係對應於入射光束284 2〇由目標施所反射之角度，造成_器·制由反射光束 286干涉參考光束282所形成之干涉光束285。如前文說明， 追縱入射光束m之角度值。後述干涉測量技術可測定由光 束轉向裝置230至目標2〇5之相對距離AR，而干涉測量技術 涉及使用光卿2波長及干涉光束285之計數條紋(例如第4 13 200525433 圖信號410)。如此目標205之相對位置包括入射光束284之 目丽角度(例如第3圖角A)、以及由光束轉向裝置23〇至目標 205之相對距離(例如第,3圖之相對距離AR)。 第4圖顯示根據本發明之具體例，由第2圖债測器 5回應於干涉光束285產生之信號。如第4圖所示，信號^〇之 波尖係對應干涉光束28S之條紋。可應用於根據本發明之具 體例之干涉測量技術，計數通過一參考點的條紋數目。光 源犯之數目及波長可用來測定參考光束加行經長度、比 較入射光束284及反射光束286行縣度之差異，獲得由光 1〇束轉向裝置230至目標2〇5之相對距離（例如幻圖之相對距 離释參考光束282行經已知距離，而入射光束Μ4及參考 光束282行經欲量測距離。 結構(絕對位置追蹤具體例） 15 參照第5圖，顯示根據本發明之具體例，追縱一目㈣$ 之絕對位置之光學位置追縱系統_之視圖。後文討論㈣ ^根據本㈣之㈣例之實騎構制。然錢著說明根 據本發明之操作具體例。 有關根據本發明之具體例之實體結構，第5圖顯示根據 本^明之具體例，追縱目標2 〃 铩2 0 5、吧對位置之光學位置追蹤 統500。如第5圖所示，光學 ，、 哭一、 九予位置追蹤糸統500有一光束產生 77以60、—鏡270、—光束轉向裝置230、-制器、-聚焦她5Q、及—處理單湖 目標205相對於光束轉 女。义 24〇,PlI^ W置23G之角度關係係結合偵測器 外目標2〇5距離光束轉向裝置230之絕對距離係 20 200525433 使用干涉測量技術測定，其仰賴光束有多重波長、以及一 干涉光束，該干涉光束係經由來自目標205之反射光與參考 光束干涉所形成。干涉光束形成原因為反射光束及參考光 束係沿不同長度路徑傳播。因此，目獅5之絕對位置係由 5目標205之角度關係及距目標2〇5之絕對距離表示。 雖然第2圖之光學位置追縱系統2〇〇可追縱目標挪之 相對位置’但光學位置追縱系統可追蹤目標2仍之絕對 位置。除非後文有其它說明，否則有關第2圖之結構討論適 用於第5圖。 10 丨似第2圖’第5圖之光學位置追縱系統500包括一光束 產生器210，其可產生由複數個波長（例如λι及切之光束 280。於本發明之具體例中，光束產生器训包括一由第一 波長λΐ之光源1以及有第二波長人2之光源2。於根據本發明 之另-具體例中，光束產生器21〇包括一光源其具有第一波 15長λΐ及第二波長λ2。於本發明之另一具體例中，光源波長 f夬速於第-波長λΐ與第二波長λ2間改變。如此經一段時 間間隔，光源具有多重波長。於根據本發明之又另一具體 例，光束產生H2H)有寬頻光源，其具有介於第_波長與第 二波長間之複數個波長。寬縣源比較其它實作可節省成 20本。至於第2圖有關光源類型的討論也同等適用於第5圖。 於根據本發明之另-具體例，光學位置追縱系統5〇〇 有複數個價測器，來偵測干涉光束挪於不同波長⑽如^ 與λ2)之分開干涉圖案。 操作（絕對位置追縱具體例） 15 200525433 後文討論根據本發明之具體例之操作細節。 參照第5圖，光學位置追蹤系統5〇〇之操作類似第2圖所 述除非有其匕說明，否則有關第2圖之操作討論適用於第 5圖。於開始追蹤目標205之前，光源丨之波長u及光源2之 5波長λ2經校準來測定相位關係。光束280包含複數個波長。 偵測器240偵測干涉光束285，其包含反射光束286及參 考光束282。處理單元220使用干涉測量技術，測定由光束 轉向裝置230至目標205之絕對距離（例如第3圖之絕對距離 R)。 φ 10 苐6圖顯示根據本發明之具體例，由第5圖光學位置追 縱系統500測得目標205之絕對位置τ。如第6圖所示，已知 光束轉向裝置230之位置S。角Α係對應於入射光束284由目 才示205反射之角度，造成偵測器240偵測干涉光束285，干涉 光束285係經由反射光束286與參考光束282干涉所形成。如 15荊文說明，入射光束284之角度值經追蹤。後文說明之干涉 測量技術允許測定由光束轉向裝置230至目標205之絕對距 離R’而干涉測量技術涉及使用複數個波長來測定絕對距離 · 。如此，目標205之絕對位置包括入射光束284之目前角度（ 例如第6圖之角A)、及由光束轉向裝置230至目標205之絕對 20 距離(例如第6圖之絕對距離R)。 當光束280有第一波長λΐ及第二波長人2時，干涉光束 285有於第一波長λΐ之第一干涉圖案、及於第二波長人2之第 二干涉圖案。干涉光束285可被分離成第一干涉圖案及第二 干涉圖案，允許分開偵測器偵測各個干涉圖案。第7圖顯示 16 200525433 #號710係對應第一干涉圖案且係由第一偵測器產生，以及 信號720係對應第二干涉圖案且係由根據本發明具體例之 第一偵成[為產生。此外，第7圖顯示根據本發明之具體例， 由第5圖之偵測器24〇回應於干涉光束285所產生之信號。換 5言之信號73〇為信號710與720之重疊。如第7圖所示，信號 710與720間之相位關係結果獲得差頻信號74〇。根據可運用 於本發明之具體例之干涉測量技術，此差頻信號74〇可經處 理來測定光源1及光源2經校準之相位關係中之相移。如此 比車乂入射光束284及反射光束286所行進之距離，允許測定 10參考光束282行進之距離，獲得由光束轉向裝置230至目標 205之絕對距離（例如第6圖之絕對距離R)。 於根據本發明之另一具體例，當利用波長調整光源時 ，干涉測量技術可將干涉圖案轉成頻率fb，其值根據類似 R (l/2)fb*v/r(*表示倍數，v為光束，及r為波長經調整光源 15之光頻變化速率）之算術關係式，決定距離目標205之絕對 距離。造成fb改變之内部延遲誤差效應容易藉校準補償值調 整R加以補償。 根據本發明之另一具體例，當利用寬頻光源時，干涉 測量技術涉及處理由偵測器240產生之信號73〇之相干性波 20峰，來得知由光束轉向裝置230至目標205之絕對距離。/ 雖然第2圖及第5圖顯示使用光束轉向裝置做二維目枳 追蹤，但須了解根據本發明之具體例經由包括一沿第三維 之光束轉向裝置，而可延伸為含括三維目標追蹤。 光學位置追蹤系統200及500提供多項優點。目標之移 17 200525433 10 15 20 動可於二維及三維追縱，同時於光學位置追蹤系統500之情 況下提供目標之絕對位置資料，而於光學位置追縱系統綱 之情況下提供目標之相對位置資料。於先前技術之相對位 置追縱系統，目標新位置之測定係依據先前目標位置決定 。當目榡係以無法被追歡方切糾(例如滑鼠*表面上 升尚），則先前技術之相對位置追縱系統無法測定新位置， 直^目襟再度係以可被追縱之方式移動為止 。相反地，若 目標係於絲位置追„統5⑽之光束掃拂空間以手寫方 式移動，則絕對位置資料提供目標之目前位置，而與先前 位置無關，有助於手寫輸入電腦系統。即使目標移動出光 學位置追縱系統遍之光束掃拂空間·之外(例如目標升 高高於光束掃拂空間），恰於目標移動人光學位置追縱系统 500之光铸拂空間範_之後，可決定目標之絕對位置。 此外，光學位置追料、统細及可提供目標之高解 析度追蹤，而不限於目標之特定表面類型。例如先前技術 之機械軌跡球滑鼠要求m才能妥為運作，先前技術之 光學滑鼠難以使用純白表面操作。有關目標，光學位置追 蹤系統200及500之操作為被動且無限制。使用光學位置追 蹤系統2〇0及5〇〇可獲得輕薄短小、低成本且低功率耗用的 實作。此外’光學位置追縱系統2〇〇及5〇〇容易擴充。第2圖 及第5圖所示元件數目足夠於短範圍用途或長範圍用料 縱目標的移動。但此等元件於此等應用用途之能力要求可 能不同。Methods and systems. An optical position tracking system includes a light beam generating an incident light beam and a reference light beam. In addition, the cast-light wind system, the tracking system further includes a beam steering device for sweeping the beam: the position chases an angle range to cause the incident beam to be reflected by a target, and the reflection of the beam through the beam is directed to interfere with the reference Beam formation ~ dry = 4 incident light, this optical position tracking system enables the use of interferometry branches = beam. The angle between the beam and the interference beam is used to determine the target position, and the input is determined based on the reflection. If the beam has a plurality of wavelengths, due to the angular value of multiple wavelengths, or multiple wavelengths at intervals, j has an absolute position of 20 marks at the same time. If the beam has a single wavelength, the relative position of the eyes can be determined. '^ A brief description of the drawings that define this item The drawings are combined with this specification and constitute an example of this specification to illustrate a specific example according to the invention, together with its description = a part, to ... explain the invention according to Matthew 6 200525433 The principle of specific examples. Fig. 1 shows a system according to a specific example of the present invention, showing an optical position tracking system. Fig. 2 shows an optical position tracking system for tracking the relative position of a target according to a specific example of the present invention. Fig. 3 shows a relative position of an object measured by the optical position tracking system of Fig. 2 according to a specific example of the present invention. Fig. 4 shows a signal generated by the detector of Fig. 2 in response to an interference beam according to a specific example of the present invention. 10 FIG. 5 shows an optical position tracking system for tracking the absolute position of a target according to a specific example of the present invention. Fig. 6 shows an absolute position of a target measured by the optical position tracking system of Fig. 5 according to a specific example of the present invention. FIG. 7 shows a plurality of signals generated by the interference beam from the detector of FIG. 5 according to a specific example of the present invention. FIG. 8A shows a circular cross section of a light beam according to a specific example of the present invention. FIG. 8B shows an elliptical cross section of a light beam according to a specific example of the present invention. Fig. 9 shows the optical position tracking system of Fig. 2 operated with a limited sweep mode according to a specific example of the present invention. 20 FIG. 10 is a flowchart showing a method for optically tracking a target according to a specific example of the present invention. [Embodiment] Detailed description of the preferred embodiment Now, the details of a specific example according to the present invention will be described. An example of the example 200525433 is illustrated in the accompanying drawings. Although the present invention will be described in conjunction with these specific examples, it should be understood that it is by no means intended to limit the present invention to these specific examples. On the contrary, the present invention is intended to cover variations, modifications, and equivalents within the spirit and scope of the present invention as defined by the appended claims. In addition, in the following, based on the detailed description of the specific examples of the present invention, a variety of specific details are stated for a thorough understanding of the present invention. In a specific example according to the present invention, an optical position tracking system includes a beam generator to generate a beam, and an optical device to generate an incident beam and a reference beam from the beam. In addition, the optical position tracking system 10 further includes a beam steering device for sweeping the incident light beam through a certain angular range, and for guiding the reflection of the incident light beam to interfere with the reference beam. When the incident light beam is reflected by a target, An interference beam is formed. The reflection of the incident light beam includes a reflected light beam. In addition, the optical position tracking system further includes a detector for detecting the interference beam, and a processing unit of 15 yuan for using the interferometry technique when the target reflects the incident beam and the interference beam provides a distance from the target. , And includes the angle of the human beam: to determine the target position. If the light beam has a plurality of wavelengths, because of the existence of these wavelengths or a period of time with multiple wavelengths, P (l determines the absolute position of the target. If the light beam has a cover-wavelength, then the relative value of the 20 targets Position. Figure 1 shows a system according to a specific example of the present invention, showing a light and position tracking system 20. The system 100 includes a computer system 50 and an optical position tracking system 20. The computer system 50 has a display 60. According to the specific example of the present invention, when the target moves in a two-dimensional space 200525433 5 10: the optical position tracking system is used to track the position of the target. The special position tracking system 20 uses at least a beam of light to sweep through the two-dimensional space The angle range is 95. When the target _ moves back and forth, left or right, or inside the two-dimensional space, the target can reflect light objects. The reflection of the light beam 90 includes a reflective beam 8G, a light beam. The tracking system 20 receives and processes to track the position of the target 10. The target 10 can be any type of object. For example, the target 1G can be a mouse-type device, a light pen, a touch screen input device, a finger, and the like. aims After ig, the reflecting surface can improve the ability of the optical position tracking system 2G to track the movement of the target 1 (). If the target 10 has sufficient reflective properties, a rear reflecting surface may not be needed. The optical position tracking system 20 generates a corresponding target by The position of the 10 position is used to track the target U) The movement can be used to input the data (for example, a cursor of 50). In another specific example of the present invention, the optical position tracking system 20 integrated display 60 provides the target 1 〇 The touch screen function when bypassing the display 60. This implementation is cheaper and less complicated than the touch screen implementation of the prior art. Structure (specific example of relative position tracking) Refer to Figure 2 and A specific example of the present invention is a view of an optical position tracking system 2000 for tracking the relative position of a target 205. The following discussion will begin with a description of the physical structure of a specific example according to the present invention. This discussion is followed by an explanation basis Operation of the specific example of the present invention. Referring to the physical structure of the specific example of the present invention, FIG. 2 shows the specific example of the present invention according to 200525433, which is used for tracking the target 205 relative A view of the installed optical position tracking system 200. The relative position is determined by polar coordinates, and "relative position" indicates the change in the position of the target 205 relative to the previous position. As shown in Figure 2, the optical position tracking system 200 has a beam generator 21 °, an optical 5 device 260, a mirror 270, a beam steering device 230, a detector 240, a focusing lens 250, and a processing unit 220. In other words, the target 205 is relative to the beam steering device 230 The angle relationship is measured in conjunction with the detector 240. In addition, the relative distance between the target 205 and the beam steering device 230 is determined using an interferometric technique, which relies on the interference of the reflected beam 286 from the target 205 and the reference beam 282 Formed interference beam 250. The reason for the formation of the interference beam 250 is that the reflected beam 286 and the reference beam 282 travel along different length paths. Thus, when the reference beam 282 and the reflected beam 286 are combined (for example, the interference beam 250), it forms an interference pattern of light and dark stripes, which is received by the interference pattern detector 24. When the difference in path length changes, the light and dark stripes are displaced. Therefore, the relative position of the target 205 is represented by the angular relationship of the target 205 and the relative distance from the target 205. The light beam is generated. . 210 produces a light beam 28. The light beam generator 21o includes a light source 212 to generate a light beam 280. The beam is coherent and has a single wavelength. The beam generator 210 has a collimating lens 214. 20 In a specific example according to the present invention, the light source (for example, the light source 212) may be based on a low-cost LED (Light Emitting Diode) technology. In another specific example of the present invention, the light source is based on V C S E L (Vertical Cavity Surface Emitting Laser) technology. According to yet another specific example of the present invention, the light source may be based on a low-cost white-heat technology with appropriate collimation capabilities. According to another specific example of the present invention, the light source may be based on a high power 10 200525433 laser based on a rare earth element. Rare earth-based lasers include, for example, Nd-YAG ('yttrium aluminum garnet) lasers and pulsed erbium lasers. High-power rare-earth-based lasers can be used when higher optical power is required for the distance and absorption between the target 205 and the detector. 5 The optical device 260 uses a light beam 280 to generate an incident light beam 284 and a reference light beam 282. In a specific example of the present invention, the optical device 260 is a beam splitter 260 °. Referring still to FIG. 2, the beam steering device 23 sweeps the incident light beam 284 through the angular range 290. In order to illustrate the sweeping movement of 10 beams 284 of incident light by the beam steering device 23, FIG. 2 shows the incident beam 284 at multiple angular positions (for example, 284A-284E). In addition, the angle of the incident light beam 284 with respect to the target 205 and the beam steering device 230 is tracked. This point is exemplified in Figure 3 and the details are discussed later. The beam steering device 230 may be any type of beam steering device. According to a specific example of the present invention, the beam steering device is a MEMS (Micro Electro Mechanical System) motor beam steering device. In another specific example of the present invention, the beam steering device is a galvanometer beam steering device. In yet another embodiment of the present invention, the beam steering device is an acoustic-beam steering device. In another specific example of the present invention, the beam steering device is an electric-beam steering device. In yet another specific example of the present invention, the light beam steering device is a light beam steering device with a grating structure. In another specific example of the present invention, the beam steering device is a full-image structure beam steering device. In another specific example of the present invention, the beam steering device is a scanning mirror beam steering device. Using MEMS processing can result in substantial cost savings and size reduction. 200525433 As shown in Figure 2, the target 205 includes a rear reflecting surface 207 to reflect the incident light beam 284 °. The term "rear reflection" indicates that the incident light beam is reflected in a direction parallel to the incident light beam. The retro-reflective surface 207 can be implemented in any manner, such as a retro-reflective tape, a retro-reflective paint, or any other retro-reflective material coupled to the target surface. As explained above, the target 205 can be any type of object. For example, the target 205 may be a mouse type device, a light pen, a touch screen input type device, a finger, and the like. If the target 205 has sufficient reflection properties, as long as the target 205 can reflect the incident light beam in a direction parallel to the incident light beam, there is no need for a rear reflection surface. For example, the movement of the office light pen with a rear reflecting surface on the writing end can be tracked, and the movement of the office light pen is used as a cursor control of a computer system. In addition, the processing unit 220 is coupled to a beam steering device 230, a detector 240, and a beam generator 21o. The processing unit 22o determines the relative position of the target 205 by using multiple data and interferometric techniques. 15 Operation (specific example of relative position tracking) The details of the operation according to the present invention will be discussed later. Referring to FIG. 2, the operation of the optical position tracking system 2000 is performed as follows. The light source 212 generates a light beam 280. The light beam 280 passes through a collimating lens 214, and the collimating lens 214 collimates the light beam 280. After passing through the collimating lens 214, the light beam 280 advances toward the 20 beam splitter 260. The beam splitter 26 uses the light beam 280 to generate an incident light beam 284 and a reference light beam 282. The reference beam 282 is directed toward the mirror 270, and the mirror reflects the reference beam 282 toward the beam splitter 260 and then sent to the detector 24o. In addition, the incident light beam 284 is directed toward the light beam steering device 230. The light beam steering device 230 sweeps the incident light beam 284 through an angular range of 29 °, so the incident light beam 284 appears at various angular positions (for example, 284A-284E). The arrows 235A and 235B here indicate that the beam steering device 230 moves to sweep the incident light beam 284 through the angular range 290. When the reflecting surface 207 behind the target 205 reflects the incident light beam 284 (e.g., 284C), the reflection system of the incident light beam 284C is reflected toward the beam steering device 230. The reflection of the incident light beam 284C includes a reflected light beam 286. The beam steering device 230 directs the reflected beam 286 to the beam splitter 260 to interfere with the reference beam 282 to form an interference beam 285. The interference beam 285 passes through the focusing lens 250, which focuses the interference beam 285 and reaches the detector 240. The detector 240 detects the interference beam 285, and instructs the processing unit 220 that the target 205 has been positioned. Therefore, the processing unit 220 records the current angle of the incident beam 284C (for example, angle A in FIG. 3). In a specific example of the present invention, the processing unit 220 tracks the angle at which the incident light beam 284 is swept by the light beam steering device 230. The detector 240 detects an interference beam 285, which includes a reflected beam 286 and a reference beam 282. The processing unit 220 determines the relative distance (e.g., the relative distance ΔK in FIG. 3) from the beam steering device 230 to the target 205 using an interferometric technique. Fig. 3 shows a specific example of the present invention. The relative position τ of the target 205 is measured by the optical position tracking system 200 of Fig. 2. As shown in Fig. 3, the position S of the light beam steering device 230 is known. The angle A corresponds to the angle at which the incident beam 284 2 is reflected by the target, resulting in an interference beam 285 formed by the reflected beam 286 and the reference beam 282. As described above, the angle value of the incident beam m is tracked. The interferometry technique described later can measure the relative distance AR from the beam steering device 230 to the target 205, and the interferometry technique involves the use of the light 2 wavelength and the counting fringes of the interference beam 285 (for example, No. 4 13 200525433 figure signal 410). Thus, the relative position of the target 205 includes the eye angle of the incident light beam 284 (for example, angle A in FIG. 3) and the relative distance from the beam steering device 23 to the target 205 (for example, the relative distance AR in FIG. 3). Fig. 4 shows a signal generated by the debt detector 5 of Fig. 2 in response to the interference beam 285 according to a specific example of the present invention. As shown in Fig. 4, the wave tip of the signal ^ 0 corresponds to the fringe of the interference beam 28S. It can be applied to a specific interferometric measurement technique according to the present invention to count the number of stripes passing a reference point. The number and wavelength of light sources can be used to determine the reference beam plus travel length, compare the difference between the incident beam 284 and the reflected beam 286, and obtain the relative distance from the light 10 beam steering device 230 to the target 205 (such as a magic map) The relative distance refers to the known distance of the reference beam 282 and the incident beam M4 and the reference beam 282 of the desired distance. Structure (specific example of absolute position tracking) 15 Referring to FIG. 5, a specific example of the present invention is shown. A view of the optical position tracking system _ of the absolute position at a glance. Discussed later ^ The actual riding structure according to the example of this example. However, the specific example of the operation according to the present invention will be explained. Figure 5 shows the physical structure of the specific example. Figure 5 shows the specific example according to the present example, tracking the target 2 〃 铩 2 0 5. The optical position tracking system 500 for the position. As shown in Figure 5, optical, Jiuyu Position Tracking System 500 has a beam generating 77, 60,-mirror 270,-beam steering device 230, -controller, -focusing her 5Q, and-processing single lake target 205 to turn female relative to the beam. Yi 24〇, PlI ^ The angle relationship between W and 23G is determined by combining the absolute distance between the target outside the detector and the distance from the beam steering device 230 to 20 200525433 using interferometry. It depends on the beam having multiple wavelengths and an interference beam. The reflected light from the target 205 interferes with the reference beam. The interference beam is formed because the reflected beam and the reference beam travel along different length paths. Therefore, the absolute position of the head 5 is determined by the angular relationship between the target 205 and the target 2 The absolute distance is expressed as 〇5. Although the optical position tracking system 2000 in Figure 2 can track the relative position of the target, the optical position tracking system can track the absolute position of target 2. Unless otherwise stated later Otherwise, the discussion about the structure of Figure 2 is applicable to Figure 5. 10 丨 The optical position tracking system 500 similar to Figure 2 'Figure 5 includes a beam generator 210, which can generate a plurality of wavelengths (such as λι and Cut beam 280. In a specific example of the present invention, the beam generator includes a light source 1 with a first wavelength λΐ and a light source 2 with a second wavelength person 2. Yu Gen According to another specific example of the present invention, the light beam generator 21 includes a light source having a first wave length 15 λΐ and a second wavelength λ2. In another specific example of the present invention, the light source wavelength f 夬 is faster than the first- The wavelength λΐ and the second wavelength λ2 are changed. In this way, after a period of time, the light source has multiple wavelengths. According to yet another specific example of the present invention, the light beam generates H2H) There is a broadband light source, which has a wavelength between the Multiple wavelengths between wavelengths. Kuanxian source can save 20 copies compared to other implementations. As for the discussion of light source types in Figure 2 is equally applicable to Figure 5. According to another-specific example of the present invention, optical position tracking The longitudinal system 500 has a plurality of valence detectors to detect the separated interference patterns where the interference beam moves to different wavelengths (such as ^ and λ2). Operation (specific example of absolute position tracking) 15 200525433 The details of the operation according to the specific example of the present invention will be discussed later. Referring to Fig. 5, the operation of the optical position tracking system 500 is similar to that described in Fig. 2. Unless there is a description of it, the discussion of the operation of Fig. 2 applies to Fig. 5. Before starting to track the target 205, the wavelength u of the light source 丨 and the wavelength λ2 of the light source 2 are calibrated to determine the phase relationship. The light beam 280 includes a plurality of wavelengths. The detector 240 detects an interference beam 285, which includes a reflected beam 286 and a reference beam 282. The processing unit 220 uses an interferometry technique to measure the absolute distance from the beam steering device 230 to the target 205 (for example, the absolute distance R in FIG. 3). Figs. φ 10 显示 6 show the absolute position τ of the target 205 measured by the optical position tracking system 500 in Fig. 5 according to a specific example of the present invention. As shown in Fig. 6, the position S of the light beam steering device 230 is known. The angle A corresponds to the angle at which the incident beam 284 is reflected by the target indicator 205, causing the detector 240 to detect the interference beam 285. The interference beam 285 is formed by the reflected beam 286 interfering with the reference beam 282. As illustrated by Jingwen 15, the angle of the incident beam 284 is tracked. The interferometry technique described later allows the absolute distance R 'from the beam steering device 230 to the target 205 to be determined. The interferometry technique involves the use of multiple wavelengths to determine the absolute distance. Thus, the absolute position of the target 205 includes the current angle of the incident light beam 284 (for example, angle A in FIG. 6), and the absolute 20 distance from the beam steering device 230 to the target 205 (for example, the absolute distance R in FIG. 6). When the light beam 280 has the first wavelength λΐ and the second wavelength person 2, the interference light beam 285 has a first interference pattern at the first wavelength λΐ and a second interference pattern at the second wavelength person 2. The interference beam 285 can be separated into a first interference pattern and a second interference pattern, allowing separate detectors to detect each interference pattern. Figure 7 shows that 16 200525433 # 710 corresponds to the first interference pattern and is generated by the first detector, and signal 720 corresponds to the second interference pattern and is generated by the first detection [for generation . In addition, FIG. 7 shows a signal generated by the detector 24 of FIG. 5 in response to the interference beam 285 according to a specific example of the present invention. In other words, the signal 73 is the overlap of the signals 710 and 720. As shown in Figure 7, the phase relationship between signals 710 and 720 results in a difference frequency signal 74. According to the interferometric measurement technique applicable to the specific example of the present invention, this difference frequency signal 74 can be processed to determine the phase shift in the calibrated phase relationship between the light source 1 and the light source 2. In this way, the distance traveled by the incident light beam 284 and the reflected light beam 286 of the car is allowed to determine the distance traveled by the reference beam 282 to obtain the absolute distance from the beam steering device 230 to the target 205 (for example, the absolute distance R in FIG. 6). In another specific example of the present invention, when a wavelength-adjusted light source is used, the interference measurement technology can convert the interference pattern into a frequency fb, the value of which is similar to R (l / 2) fb * v / r (* represents a multiple, v Is the light beam, and r is the arithmetic relationship of the wavelength of the light source 15 (the rate of change of the optical frequency of the light source 15 is adjusted), which determines the absolute distance from the target 205. The effect of internal delay error that causes fb to change is easily compensated by adjusting R for the calibration compensation value. According to another specific example of the present invention, when a broadband light source is used, the interferometry technique involves processing 20 peaks of coherent waves of the signal 73 generated by the detector 240 to obtain the absolute distance from the beam steering device 230 to the target 205 . / Although Figures 2 and 5 show the use of a beam steering device for two-dimensional eye tracking, it must be understood that according to a specific example of the present invention, by including a beam steering device along the third dimension, it can be extended to include three-dimensional target tracking. . Optical position tracking systems 200 and 500 provide several advantages. The movement of the target 17 200525433 10 15 20 can be tracked in two and three dimensions. At the same time, the absolute position data of the target is provided in the case of the optical position tracking system 500, and the relative of the target is provided in the case of the optical position tracking system. Location data. In the relative position tracking system of the prior art, the new target position is determined based on the previous target position. When the eyepieces are not corrected by the chasing party (such as the mouse * the surface is still up), the relative position tracking system of the prior art cannot determine the new position, and the eyepieces move again in a way that can be pursued until. Conversely, if the target is moved by hand in a beam sweeping space following the position of the wire, the absolute position data provides the current position of the target, regardless of the previous position, and is helpful for handwriting input into the computer system. Even if the target moves Beyond the beam swept space of the optical position tracking system (for example, the target rises higher than the beam swept space), it is just after the light moving range of the optical position tracking system 500 of the target moving person. The absolute position of the target. In addition, the optical position tracking, detailing, and high-resolution tracking of the target can be provided, not limited to the specific surface type of the target. For example, the mechanical trackball mouse of the prior art requires m to work properly. Previously, The optical mouse of the technology is difficult to operate with a pure white surface. Regarding the target, the operation of the optical position tracking systems 200 and 500 is passive and unlimited. Using the optical position tracking systems 2000 and 500 can achieve thinness, shortness, low cost and low Implementation of power consumption. In addition, the 'optical position tracking system 2000 and 500 are easily expandable. The number of components shown in Figure 2 and Figure 5 Enough to use short-range or long range target with the vertical movement of the material, but the ability to use applications of these elements may be different requirements thereto.
第8A圖顯示根據本發明之具體例，光束之圓形截面 18 200525433 800A。有此種圓形截面800A之亦忐_ 尤果可用於光學位置追蹤系 統·(第2圖）及谓(第5圖）。圓形截面嶋命小，則光學位 置追縱系統·(第2圖）及500(第5圖）之解析度愈高。 5 10 第则顯示根據本發明之具體例，光权橢圓截面 _B。具錢WGB之光切祕絲位置追縱系統 細(第2圖)及遍(第5圖)，來當目標2〇5係垂直於光束轉向 裝置之掃拂方向移動時，提供若干追縱公差。因橢圓截面 8_係垂直_方向延伸，故光學位置追料統職第⑽ )及500(第5圖）之追縱範圍可垂直於掃拂方向延伸。 第9圖說明根據本發明之具體例，第·之光學位置追 蹤系統200於有限掃拂模操作。第2圖巾，光束轉向裝置23〇 掃拂通過全角度U29G ;第9®中，光束轉向裝置23〇掃拂 通過有限角度範圍295。此種有限掃拂模可提高目標2〇5之 定位速度，且可提升解析度。 15 貫際上，光束轉向裝置230最初係以全掃描模（例如全 角度範圍290)操作。但一旦目標2〇5相對於光束轉向裝置 230於第一角度定位，則光束轉向裝置23〇環繞第一角度掃 拂有限角度範圍295，故入射光束284出現於各個角度位置( 例如284A-284C)。此種光束轉向裝置23〇之有限度移動於一 20段短時間内未預期目標2〇5之移動有顯著變化時可提供顯 著效果。當目標205於有限掃拂模，不再反射入射光束時， 光束轉向裝置230返回以全掃拂模操作。 有關第9圖之討論同等適用於第5圖之光學位置追礙系 統500 〇 200525433 第ίο圖為流稃圖，顯不根據本發明之具體例，一種光 學追蹤一目標之方法1〇〇〇。 於步驟1010，參考光束及入射光束係由光束產生。若 光束有單一波長，則町追蹤目標之相對位置。若光束有多 5重波長，無論係由於同時存在有此等波長 ，或經一段時間 間隔有多重波長，町追蹤目標之絕對位置。繼續於步驟1020 ’入射光束藉光束轉向裝置掃拂通過一角度範圍。此外該 入射光束之角度範圍經測定。 此外，於步驟1030，當目標反射入射光束來產生反射 1〇光束時，反射光束被送至干涉參考光束來形成干涉光束。 於步驟1040,目標位置係使用干涉测量技術利用資料 列定。使用之資料例如為當目標反射入射光束時入射光束 之角度值、以及干涉光束其提供由光束轉向裝置至該目標 之距離等資料。 5 ▲已經呈現前文根據本發明之特定具體例之說明來舉例 說明及描述。但此等說明並非排它性，或限制本發明於所 揭示之精確形式，反而鑑於前文教示可做出多項修改及變 化。具體例經選出及描述來最徹底明白解釋本發明之原理 及其實際應用，藉此讓熟諳技藝人士可最佳利用本發明及 〇各具體例帶有適合預期使用之特定用途之各項修改。預期 本發明之範圍係由隨附之申請專利範圍及其相當範圍界 〇 【圖式簡單說明】 第1圖顯示根據本發明之具體例之系統，顯示一種光學 20 200525433 位置追蹤系統。 第2圖顯示根據本發明之具體例，一種用於追蹤目標之 相對位置之光學位置追蹤系統。 第3圖顯示根據本發明之具體例，由第2圖之光學位置 5 追蹤系統測得一目標之相對位置。 第4圖顯示根據本發明之具體例，由第2圖之偵測器回 應於干涉光束所產生之一信號。 第5圖顯示根據本發明之具體例，一種用於追蹤目標之 絕對位置之光學位置追蹤系統。 10 第6圖顯示根據本發明之具體例，由第5圖之光學位置 追蹤系統測得一目標之絕對位置。 第7圖顯示根據本發明之具體例，由第5圖之偵測器回 應於干涉光束所產生之多個信號。 第8A圖顯示根據本發明之具體例，光束之圓形截面。 15 第8B圖顯示根據本發明之具體例，光束之橢圓截面。 第9圖顯示根據本發明之具體例，以有限掃拂模操作之 第2圖光學位置追蹤系統。 第10圖為一流程圖，顯示根據本發明之具體例一種光 學追蹤一目標之方法。 80.. .反射光束 90…光束 95.. .角度範圍 100…系統 20 【主要元件符號說明 10".目標 20.. .光學位置追蹤系統 50.. .電腦糸統 60.. .顯示器 21 200525433 200…光學位置追蹤系統 284…入射光束 205...目標 284A-E…角度位置 207...後反射面 285…干涉光束 210...光束產生器 286...反射光束 212...光源 290…角度範圍，全角度範圍 214...準直透鏡 295...有限角度範圍 220…處理單元 410...信號 230...光束轉向裝置 500…光學位置追蹤系統 235A，235B···箭頭 710-730...信號 240...偵測器 740...差頻信號 250...聚焦透鏡 800A…圓形截面 260...光學裝置，分束器 800B...橢圓截面 270…鏡 1000...方法 280…光束 282...參考光束 1010-1040···步驟 22Fig. 8A shows a circular cross section of a light beam according to a specific example of the present invention. 18 200525433 800A. Even with this circular cross section 800A, Yogo can be used in optical position tracking systems (Figure 2) and predicates (Figure 5). The smaller the circular cross section, the higher the resolution of the optical position tracking system (Figure 2) and 500 (Figure 5). 5 10 shows a specific example of the light weight elliptical cross section _B according to the present invention. The WGB light-cutting mystery silk position tracking system is thin (Figure 2) and full (Figure 5) to provide several tracking tolerances when the target 205 moves perpendicular to the sweep direction of the beam steering device. . Because the elliptical cross section 8_ is perpendicular to the direction, the tracking range of the optical position tracking unit) and 500 (picture 5) can extend perpendicular to the sweep direction. Fig. 9 illustrates the operation of the optical position tracking system 200 in a limited sweep mode according to a specific example of the present invention. In the second figure, the beam steering device 23 is swept through the full angle U29G; in the 9th®, the beam steering device 23 is swept through the limited angle range 295. This limited sweep mode can increase the positioning speed of the target 205 and the resolution. 15 Traditionally, the beam steering device 230 was originally operated in a full scan mode (e.g., full angle range 290). However, once the target 205 is positioned at a first angle relative to the beam steering device 230, the beam steering device 23 sweeps a limited angular range 295 around the first angle, so the incident beam 284 appears at various angular positions (for example, 284A-284C) . Such a limited movement of the beam steering device 23 can provide a significant effect when a significant change in the movement of the target 205 is not expected in a short period of 20 segments. When the target 205 is in the limited sweep mode and no longer reflects the incident beam, the beam steering device 230 returns to the full sweep mode. The discussion about FIG. 9 is equally applicable to the optical position tracking system 500 of FIG. 5 200505433 The figure is a flow chart, showing that according to a specific example of the present invention, a method of optically tracking an object is 1000. In step 1010, the reference beam and the incident beam are generated by the beam. If the beam has a single wavelength, the relative position of the target is tracked. If the beam has more than 5 wavelengths, whether it is due to the simultaneous existence of these wavelengths or multiple wavelengths over a period of time, the absolute position of the target is tracked. Continuing at step 1020, the incident light beam is swept through a range of angles by the light beam steering device. In addition, the angular range of the incident beam was measured. In addition, in step 1030, when the target reflects the incident beam to generate a reflected 10 beam, the reflected beam is sent to an interference reference beam to form an interference beam. In step 1040, the target position is determined using interferometric techniques using data. The data used are, for example, the angle of the incident beam when the target reflects the incident beam, and the interference beam which provides the distance from the beam steering device to the target. 5 ▲ The foregoing has been illustrated and described based on the description of specific specific examples of the present invention. However, these descriptions are not exclusive or limit the invention to the precise form disclosed. Rather, many modifications and variations can be made in light of the foregoing teachings. The specific examples are selected and described to explain the principle and practical application of the present invention in the most thorough way, so that those skilled in the art can make the best use of the present invention and each specific example has various modifications suitable for the specific use intended. It is expected that the scope of the present invention is bounded by the scope of the attached patent application and its equivalent scope. [Brief description of the drawings] Figure 1 shows a system according to a specific example of the present invention, showing an optical 20 200525433 position tracking system. Fig. 2 shows an optical position tracking system for tracking the relative position of a target according to a specific example of the present invention. Fig. 3 shows the relative position of an object measured by the optical position 5 tracking system of Fig. 2 according to a specific example of the present invention. Fig. 4 shows a signal generated by the detector of Fig. 2 in response to an interference beam according to a specific example of the present invention. Fig. 5 shows an optical position tracking system for tracking the absolute position of a target according to a specific example of the present invention. 10 Fig. 6 shows an absolute position of an object measured by the optical position tracking system of Fig. 5 according to a specific example of the present invention. Fig. 7 shows a plurality of signals generated by the detector of Fig. 5 in response to an interference beam according to a specific example of the present invention. FIG. 8A shows a circular cross section of a light beam according to a specific example of the present invention. 15 FIG. 8B shows an elliptical cross section of a light beam according to a specific example of the present invention. Fig. 9 shows an optical position tracking system of Fig. 2 operated with a limited sweep mode according to a specific example of the present invention. FIG. 10 is a flowchart showing a method for optically tracking a target according to a specific example of the present invention. 80 .. Reflected beam 90 ... Beam 95..Angle range 100 ... System 20 [Description of main component symbols 10 ". Target 20 ... Optical position tracking system 50 .. Computer system 60 .. Display 21 200525433 200 ... Optical position tracking system 284 ... Incoming beam 205 ... Targets 284A-E ... Angular position 207 ... Back reflecting surface 285 ... Interference beam 210 ... Beam generator 286 ... Reflected beam 212 ... Light source 290 ... Angle range, full angle range 214 ... Collimating lens 295 ... Limited angle range 220 ... Processing unit 410 ... Signal 230 ... Beam turning device 500 ... Optical position tracking system 235A, 235B ... Arrow 710-730 ... signal 240 ... detector 740 ... differential frequency signal 250 ... focusing lens 800A ... circular cross section 260 ... optical device, beam splitter 800B ... elliptical cross section 270 ... mirror 1000 ... method 280 ... beam 282 ... reference beam 1010-1040 ... step 22