1270663 九、發明說明： 【發明所屬之技術領域】 本發明係涉及一種位移量測系統，尤其是應用外差干涉 術用以量測位移，並且為準共光程架構之一種外差干涉位移 量測系統。 【先前技術】 對於應用光柵的光學位移量測系統而言，係利用高同調 性的光源入射繞射光柵（diffractiongrating)後產生至少 兩束繞射光，將此兩束繞射光經由光學元件而互相干涉，而 此干涉訊號具有週期性的變化趨勢，當光柵移動時，此干涉 訊號亦發生變化，相關技術如美國專利公告號第3891321號 專利，由於當時的光栅製造技術，僅可量測一維的位務量。 隨著技術的演進，使得多維度的量測漸漸被發展，如美 國專利公告號第5204524號專利、第5493397號專利、第 36631005號專利與第6744520號專利，皆是利用測量繞射光 強度為主，並為零差（h〇m〇dyne)的量測裝置。 我們知道外差干涉術（heter〇dyne interfer〇metry) 係將兩個些微頻差的光波分別引入兩個干涉路徑中，使得干 β儀輪出的光強度產生酬性變化，振盪頻轉於兩光波的 頻率差，而待測干涉相位是載在此具有特定頻率的訊號上， 將量測訊號與參考訊號混頻，經解調（demodulate)後，可 1270663 得出干涉相位，由於振盪頻率高又為已知值，所以能避開低 頻雜訊干擾，並且相位靈敏度與解析度都很高，是一種非常 重要的微弱訊號量測技術。 因為外差干涉術的量測特色，所以此技術又稱雙頻干涉 術（two frequency interferometry)或交流干涉術（ac interferometry )，可用作位移、表面輪廓、動態參數等量測。 然而傳統外差干涉術其外在環境的兩個光束容易被影 響，而彼此之間產生相位差，此相位差無法消除，如此會增 加量測的不確定性。 另外，利用單一偏振光的位移量測系統必須將光強度轉 換為相位來解析，於訊號處理的部份搭配著電子細分割手 法，並且需抑制周圍環境光來進行量測，雖量測精度可達次 奈米等級，但是如此在制架構上變得較繁複且增加量測的 不便與不準確性。 【發明内容】 赛於赴關題，本發_主要目的在於提供—種準共 光程外差干涉轉制級，彻利射卜差干涉相位量^ 高靈敏度’且經特殊設計使得光學轉可相不受外在環境 擾動的高穩定性。直接量測因位移所造成的相位變化量= 式，可以使量測精度達到次奈米等級。 因此’為達上述目的，本發明据 ^ ’揭路之—鮮共光程外 1270663 差干涉位移制祕，外差光源產生參考光與信號光， 亚且將信號光人射光柵而產生繞射光，此繞射光再經由偏極 分光鏡而分為第-繞射光與第二繞射光，並且使參考光、第 一繞射光與第二繞射光分別入射偏振板而產生參考干涉光、 第一干涉光與第二干涉光，將此參考干涉光、第一干涉光與 第二干涉光傳人峨處理裝置，以制相位差，當光拇移動 時，此訊號處理裝置量得參考干涉光、第一干涉光與第二干 涉光之相位差，進而可得光柵之位移量。 其中此繞射光係包含正一階繞射光與負一階繞射光，正 一階繞射光入射偏極分光鏡一側，而負一階繞射光入射偏極 分光鏡另一侧，以使正一階繞射光與負一階繞射光以相互垂 直之角度a射偏極分級並相互重合後，且侧通過偏振 板之後而形成第一及第二干涉光。 所以本發明之準共光程外差干涉位移量測系統，係利用 準共光程（quasi common path)外差光學架構，以降低外界 環土兄擾動秘響’且提高位移量測靈敏度。若搭配越細線距 的光栅，可量測至皮米（pic〇-meter)等級的微小位移量。 有關本發明的特徵與實作，茲配合圖示作最佳實施例詳 細說明如下。 【實施方式】 叫芩閱「第1圖」，所示為本發明之系統架構圖，本發 1270663 月係種準共光程外差干涉位移量測系統，係利用一外差光 、原 係為星，則光源，此外差光源（heterodyne 1 ight source) 100係可輸出包含兩個不同頻率的光波，而且此兩 個光波係為相互正交的線偏振光，所以此兩光波並不會產生 干"田此外差光源⑽入射一分光鏡（beam splitter) 300 後’便分為參考光U〇與信號光130 ,此參考光110係直接 入射方位角為45度的參考光偏振板（p〇iarizer) 3ΐγ，使得 外差光源100中的兩正交線偏振光互相干涉而產生參考干涉 光170 ’並經由訊號處理裝置700的參考光感測器710所接 收’所以此參考干涉光170的數學形式可表示為： ^DR =^[l+ 0 另外#號光130係直接入射裝設有光栅410的移動平台 450中，使信號光13〇入射光柵41〇後，便產生若干繞射光 150 ’若此光栅41〇為一維光柵41〇時，便會沿一維方向繞射 出許多的光，我們稱為繞射光150，除了中間零階的繞射光 以外’沿此零階的繞射光兩邊所產生的繞射光我們稱為正一 階繞射光151，另一側的繞射光150稱為負一階繞射光152， 依序再產生正二階繞射光150與負二階繞射光150，依此類 推，而本實施例係取用正一階繞射光151與負一階繞射光 152’此正一階繞射光151與負一階繞射光152在經由反射元 件330、330a的轉向而共同入射一偏極分光鏡350，使不同 10 1270663 偏振態的光被偏極分光鏡350所分開，並且我們將此正交的 偏振態稱為P偏振與S偏振，偏極分光鏡3〇〇係可使p偏振 的光通過，而S偏振的光係被反射。先前提到外差光源丄〇〇 係由兩個正交的線偏振光所組成，所以此正一階繞射光151 與負一階繞射光152亦包含此兩正交的線偏振光，即p偏振 與S偏振，當正一階繞射光151與負一階繞射光152由偏極 分光鏡350相互垂直的兩侧入射時，便會使正一階繞射光κι 的P偏振通過，而負一階繞射光152的s偏振被反射而相互 重合於一起而成為第一繞射光160，此第一繞射光16〇經過 45度角的苐一偏振板310而產生第一干涉光in，而由訊號 處理裝置700之第一感測器730所接收，此時的第一干涉光 171的數學表示為： 係為正一階繞射光151與負一階繞射光152所走之路徑差 (path difference)而產生的相位差，而以系為光柵41〇移 動Δχ時所產生的相位差。其中，，式中m係代表繞 射階數’ d係代表光栅410的線距寬度。 另外，正一階繞射光151的S偏振被偏極分光鏡350所 反射，而負-階繞射光152的p偏振直接穿過偏極分光鏡35〇 而相互重合於一起而成為第二繞射光161，此第二繞射光i6i 經過45度角的第二偏振板311而產生第二干涉光173，而由 11 1270663 訊號處理裝置7GG之第二感測器75()所接收，此時的第二干 涉光173的數學表示為： 4 + 2^)〜+1)_(ω卜也—多J]。 因此，當訊號處理裝置700透過參考光感測器71〇、第 一感測器730與第二感測器750而接收參考干涉光17〇、第 一干涉光171與第二干涉光173可量得光柵41〇移動&時所 產生的相位差知，再利用已知的條件，如繞射階數m與光柵 410的線距寬度d即可求出光柵41〇的位移^，並且根據上 式，我們可知雖然正一階繞射光151與負一階繞射光152並 不為相同光程相同路徑，但是最後干涉訊號之相位差並不受 此影響，所以，其正-階繞射光151與負一階繞射光152雖 未同路徑傳遞，但是並不會影響，所以正一階繞射光151與 負卩白纟九射光152可谓準共光程’因此，本發明的光學架構 便可承受較高的環境變異的容忍度。 本實施例係選用正一階繞射光151與負一階繞射光 152 ’但疋可根據不同的量測範圍大小而選擇不同階的繞射光 150，如二階或三階等。 上述的反射元件330、330a可為反射鏡、直角稜鏡等元 件，以使正一階繞射光151與負一階繞射光152轉向而朝向 偏極分光鏡350入射。 並且光柵410為反射式光栅（reflecti〇n grating)或 12 1270663 是亦有人稱閃耀光栅（blazedgrating)，此光栅410係可用 金屬薄膜或介電質薄膜所製成，將此薄膜鍍於玻璃基板或矽 基板，以形成具有週期性的線距，而目前半導體製程技術其 最小寬度約90奈米，所以當光柵410的線距寬度越小時，其 量測度精度越高。 請參閱「第2圖」，所示為本發明之另一實施例系統架 構圖，係沿用上一實施例的光學架構，此光柵410係為二維 光栅（two-dimension grating)或稱為交叉光栅（ cross grating)，一維光栅430係可使入射光入射後產生二維繞射 光150，所以當外差光源100產生的光入射分光鏡3〇〇後， 成為信號光130與參考光no，此參考光係直接入射方 位角為45度的偏振板31〇，使得外差光源1〇〇中的兩正交線 偏振光互相干涉^產生參考干涉光17G，並經由訊號處理裝 置700的參考光感測器71〇所接收。 另外信號光130係直接入射裝設有二維光柵430的移動 平台450中，使信號光130入射光柵410後，便沿著二維方 :’二X-Y方向產生多個繞射光15〇，其中中間的繞射光為 零階繞縣，沿此零_繞射光沿X方向兩邊所產生的繞射 光我們稱為X方向的第—正—階繞射光153，另—側的繞射 光私為X方向的第—負—階繞射光154，而另—維度（即Y 軸）的繞射光150麵γ方向的第二正一階繞射光155，另 1270663 一側的繞射光150係Α γ古々 于局Υ方向的弟二負一階繞射光156，當 ’、、i其匕方向亦會有其它更高階的繞射光⑽，但因本實施係 取用X方向與Y方向的正_階繞射光與負—階繞射光，所以 以此為討論，為說明簡潔，對於X方向的第-正-階繞射光 153、x方向的第—負—階繞射光154、Y方向的第二正-階 、、几射光155與Y方向的第二負一階繞射光156，直接稱為第 一正一階繞射光153、第一負一階繞射光154、第二正一階繞 射光155與第二負一階繞射光Mg。 而第一正一階繞射光丨53與第一負一階繞射光丨54在經 由反射兀件330b、330c的轉向而共同入射一第一偏極分光鏡 370使不同偏振恶的光被偏極分光鏡所分開，因外差光 源100係由兩個正交的線偏振光所組成，所以此第一正一階 繞射光153與第一負一階繞射光154亦包含此兩正交的線偏 振光，即P偏振與S偏振，當第一正一階繞射光153與第一 負一階繞射光154由第一偏極分光鏡370相互垂直的兩側入 射時，便會使正一階繞射光151的P偏振通過，而負一階繞 射光152的s偏振被反射而重合於一起而成為第一繞射光 160 ’此第一繞射光160經過45度角的第一偏振板310而產 生X方向的第一干涉光171，而由訊號處理裝置700之第一 感測為730所接收。 另外，第一正一階繞射光153的S偏振被第一偏極分光 14 12706631270663 IX. Description of the Invention: [Technical Field] The present invention relates to a displacement measuring system, in particular to heterodyne interferometry for measuring displacement, and a heterodyne interference displacement of a quasi-common optical path architecture Measurement system. [Prior Art] For an optical displacement measuring system using a grating, at least two diffracted lights are generated by a high-coherence light source incident diffraction grating, and the two diffracted lights interfere with each other via an optical element. The interfering signal has a periodic trend of change. When the grating is moved, the interfering signal also changes. Related art, such as U.S. Patent No. 3,891,321, can only measure one-dimensional by the grating manufacturing technology at that time. Bit traffic. With the evolution of technology, multi-dimensional measurement is gradually being developed. For example, U.S. Patent No. 5,204,524, U.S. Patent No. 5,493,397, U.S. Patent No. 3,631,005, and No. 6,744,520 are all based on measuring the intensity of diffracted light. And a measurement device with zero difference (h〇m〇dyne). We know that heterodyne interferometry is to introduce two light waves with different frequency differences into two interference paths, so that the light intensity of the dry beta meter produces a change in the intensity, and the oscillation frequency is converted to two. The frequency difference of the light wave, and the interference phase to be measured is carried on the signal with a specific frequency, the measurement signal is mixed with the reference signal, and after demodulation, the interference phase can be obtained by 1270663, because the oscillation frequency is high. It is also a known value, so it can avoid low-frequency noise interference, and has high phase sensitivity and resolution. It is a very important weak signal measurement technology. Because of the measurement characteristics of heterodyne interferometry, this technique, also known as two-frequency interferometry or ac interferometry, can be used for displacement, surface contour, dynamic parameters, etc. However, in the traditional heterodyne interferometry, the two beams of the external environment are easily affected, and a phase difference is generated between them. This phase difference cannot be eliminated, which increases the uncertainty of the measurement. In addition, the displacement measurement system using a single polarized light must convert the light intensity into phase for analysis. The signal processing part is matched with the electronic fine segmentation method, and the surrounding ambient light needs to be suppressed for measurement, although the measurement accuracy can be Up to the nano level, but this has become more complicated in the architecture and increased the inconvenience and inaccuracy of measurement. [Summary of the Invention] In the game, the main purpose of this issue is to provide a quasi-common optical path heterodyne interference conversion stage, the sharp interference difference phase quantity ^ high sensitivity ' and specially designed to make the optical phase change High stability that is not disturbed by the external environment. Direct measurement of the amount of phase change caused by the displacement = can make the measurement accuracy reach the sub-nano level. Therefore, in order to achieve the above object, the present invention is based on the principle that the differential optical source generates a reference light and a signal light, and the heterodyne light source generates a reference light and a signal light, and the signal light is incident on the grating to generate a diffracted light. The diffracted light is further divided into first-diffractive light and second diffracted light via a polarizing beam splitter, and the reference light, the first diffracted light and the second diffracted light are respectively incident on the polarizing plate to generate reference interference light, the first interference The light and the second interference light transmit the reference interference light, the first interference light and the second interference light to the processing device to make a phase difference. When the light thumb moves, the signal processing device measures the reference interference light, first The phase difference between the interference light and the second interference light, and the amount of displacement of the grating can be obtained. The diffracted light system includes positive first-order diffracted light and negative first-order diffracted light, and positive first-order diffracted light is incident on one side of the polarizing beam splitter, and negative first-order diffracted light is incident on the other side of the polarizing beam splitter to make positive one The order diffracted light and the negative first-order diffracted light are polarized at mutually perpendicular angles a and are superposed on each other, and the first and second interfering lights are formed after the side passes through the polarizing plate. Therefore, the quasi-common optical path heterodyne interference displacement measuring system of the present invention utilizes a quasi common path heterodyne optical architecture to reduce the external ringing disturbance and improve the displacement measurement sensitivity. If you match a grating with a finer line spacing, you can measure the small amount of displacement to the pic〇-meter level. The features and implementations of the present invention are described in detail with reference to the preferred embodiments. [Embodiment] Referring to "1st picture", the system architecture diagram of the present invention is shown. The 1270663 type quasi-common optical path heterodyne interference displacement measurement system utilizes an external difference light and original system. For the star, the light source, and the difference source (heterodyne 1 ight source) 100 series can output light waves containing two different frequencies, and the two light waves are mutually orthogonal linearly polarized light, so the two light waves are not generated. The dry " field difference light source (10) is incident on a beam splitter 300 and is then divided into reference light U 〇 and signal light 130, which is a direct reference light polarizing plate with azimuth angle of 45 degrees (p) Ϊ́iarizer) 3ΐγ, such that two orthogonal linearly polarized lights in the heterodyne light source 100 interfere with each other to generate reference interference light 170' and are received by reference light sensor 710 of signal processing device 700, so this reference interference light 170 The mathematical form can be expressed as: ^DR =^[l+ 0 The other #130 light is directly incident on the moving platform 450 equipped with the grating 410, so that after the signal light 13 is incident on the grating 41, a plurality of diffracted lights 150' are generated. If the grating 41 is one When the grating is 41 ,, a lot of light is emitted in a one-dimensional direction. We call it diffracted light 150. In addition to the intermediate zero-order diffracted light, the diffracted light generated along both sides of the zero-order diffracted light is called positive. The first-order diffracted light 151 and the other side of the diffracted light 150 are referred to as negative first-order diffracted light 152, and sequentially generate positive second-order diffracted light 150 and negative second-order diffracted light 150, and so on, and this embodiment takes positive First-order diffracted light 151 and negative first-order diffracted light 152'. The first-order diffracted light 151 and the negative first-order diffracted light 152 are incident on a polarizing beam splitter 350 together by steering of the reflective elements 330, 330a, making the difference 10 1270663 The light of the polarization state is separated by the polarization beam splitter 350, and we refer to this orthogonal polarization state as P polarization and S polarization, and the polarization beam splitter 3 can pass p-polarized light, while the S polarization The light system is reflected. It is mentioned that the heterodyne light source is composed of two orthogonal linearly polarized lights, so the positive first-order diffracted light 151 and the negative first-order diffracted light 152 also include the two orthogonal linearly polarized lights, that is, p Polarization and S polarization, when positive first-order diffracted light 151 and negative first-order diffracted light 152 are incident on both sides perpendicular to each other by polarized beam splitter 350, P-polarization of positive first-order diffracted light κι is passed, and negative one The s-polarization of the order diffracted light 152 is reflected and overlaps with each other to become the first diffracted light 160. The first diffracted light 16 passes through the polarizing plate 310 at a 45-degree angle to generate the first interfering light in, and the signal is generated by the signal. The first sensor 730 of the processing device 700 receives the mathematical representation of the first interference light 171 at this time: the path difference between the positive first-order diffracted light 151 and the negative first-order diffracted light 152. The resulting phase difference is the phase difference produced when the grating 41 〇 moves by Δχ. Here, m represents the diffraction order 'd system represents the line width of the grating 410. In addition, the S polarization of the first-order diffracted light 151 is reflected by the polarization beam splitter 350, and the p-polarization of the negative-order diffracted light 152 directly passes through the polarization beam splitter 35 〇 and coincides with each other to become the second diffracted light. 161, the second diffracted light i6i passes through the second polarizing plate 311 at a 45-degree angle to generate the second interference light 173, and is received by the second sensor 75() of the 11 1270663 signal processing device 7GG. The mathematical representation of the two interfering lights 173 is: 4 + 2^) ~ +1) _ (ω 卜 - more J). Therefore, when the signal processing device 700 transmits the reference photo sensor 71 〇, the first sensor 730 Receiving the reference interference light 17 与 with the second sensor 750, the first interference light 171 and the second interference light 173 can measure the phase difference generated when the grating 41 〇 moves & and then using known conditions, For example, the displacement of the grating 41〇 can be obtained by the diffraction order m and the line width d of the grating 410. According to the above formula, we know that although the first-order diffracted light 151 and the negative first-order diffracted light 152 are not the same The optical path is the same path, but the phase difference of the last interference signal is not affected by this, so its positive-order diffracted light 151 and Although the first-order diffracted light 152 is not transmitted in the same path, it does not affect, so the positive first-order diffracted light 151 and the negative first-order diffracted light 152 can be said to be quasi-optical paths. Therefore, the optical structure of the present invention can withstand higher The tolerance of the environmental variation. In this embodiment, the first-order diffracted light 151 and the negative first-order diffracted light 152 ' are selected, but different orders of diffracted light 150, such as second or third order, may be selected according to different measurement range sizes. The above-mentioned reflective elements 330, 330a may be mirrors, right angles, etc., such that the positive first order diffracted light 151 and the negative first order diffracted light 152 are turned toward the polarizing beam splitter 350. And the grating 410 is reflected. A grating (reflecti〇n grating) or 12 1270663 is also known as a blazed grating. The grating 410 can be made of a metal film or a dielectric film, and the film is plated on a glass substrate or a germanium substrate to form With a periodic line spacing, the current semiconductor processing technology has a minimum width of about 90 nm, so the smaller the line width of the grating 410, the higher the accuracy of the measurement. Please refer to "Fig. 2" A system architecture diagram of another embodiment of the present invention is the optical architecture of the previous embodiment. The grating 410 is a two-dimension grating or a cross grating, and a one-dimensional grating 430. The incident light is incident to generate two-dimensional diffracted light 150. Therefore, when the light generated by the heterodyne light source 100 is incident on the beam splitter 3, it becomes the signal light 130 and the reference light no. The direct incident azimuth angle of the reference light system is 45. The polarizing plate 31 is so that the two orthogonal linearly polarized lights in the heterodyne light source 1 互相 interfere with each other to generate the reference interference light 17G, and are received by the reference light sensor 71 讯 of the signal processing device 700. In addition, the signal light 130 is directly incident on the moving platform 450 on which the two-dimensional grating 430 is mounted. After the signal light 130 is incident on the grating 410, a plurality of diffracted lights 15 产生 are generated along the two-dimensional side: 'two XY directions, wherein the middle The diffracted light is zero-order around the county, and the diffracted light generated along the X-direction along the zero-diffracted light is called the first-positive-order diffracted light 153 in the X direction, and the diffracted light on the other side is in the X direction. The first-negative-order diffracted light 154, and the other-dimension (i.e., the Y-axis) of the diffracted light 150 is in the γ-direction of the second positive first-order diffracted light 155, and the other 1270663-side diffracted light 150 is Α 々 The second direction of the Υ direction is the first-order diffracted light 156. When the ', i are in the 匕 direction, there will be other higher order diffracted light (10), but this embodiment uses the positive-order diffracted light in the X direction and the Y direction. Negative-order diffracted light, so for the sake of brevity, for the first-order-order diffracted light 153 in the X direction, the first-negative-order diffracted light 154 in the x direction, and the second positive-order in the Y direction, a plurality of second-order diffracted lights 156 in the Y direction, directly referred to as first positive first-order diffracted lights 153, first First-order diffracted light 154, a positive second-order output light 155 about a second-order diffracted light of negative Mg. The first positive first-order diffracting aperture 53 and the first negative first-order diffracting aperture 54 are incident on the first polarizing beam splitter 370 through the steering of the reflecting elements 330b, 330c, so that the light of different polarizations is polarized. The beamsplitters are separated, and since the heterodyne light source 100 is composed of two orthogonal linearly polarized lights, the first positive first order diffracted light 153 and the first negative first order diffracted light 154 also include the two orthogonal lines. Polarized light, that is, P polarization and S polarization, when the first positive first order diffracted light 153 and the first negative first order diffracted light 154 are incident on both sides perpendicular to each other by the first polarizing beam splitter 370, the first order is made The P-polarization of the diffracted light 151 passes, and the s-polarization of the negative first-order diffracted light 152 is reflected and overlaps to become the first diffracted light 160'. The first diffracted light 160 is generated by the first polarizing plate 310 at an angle of 45 degrees. The first interfering light 171 in the X direction is received by the first sensing of the signal processing device 700 as 730. In addition, the S polarization of the first positive first-order diffracted light 153 is split by the first polarized light 14 1270663
鏡370所反射，而第一負一階繞射光154的p偏振直接穿過 偏極分光鏡350而相互重合於一起而成為第二繞射光161， 此第二繞射光161經過45度角的第二偏振板31ι而產生X 方向的第二干涉光丨73，而由訊號處理裝置7〇〇之第二感測 器750所接收。 對於第_正一階繞射光155與第二負一階繞射光156亦 經由反射元件330d、330e而共同入射第二偏極分光鏡39〇， 並且為弟—偏極分光鏡390相互垂直的兩側入射，如此便使 弟一正一階繞射光155的P偏振通過，而第二負一階繞射光 156的S偏振被反射而重合於一起而成為第三繞射光ι63 ,此 第三繞射光163經過45度角的第三偏振板313而產生γ方向 的第三干涉光175,而由訊號處理裝置700之第三感測器770 所接收。 而對於第二正一階繞射光155的S偏振被第二偏極分光 鏡390所反射，而第二負一階繞射光156的p偏振直接穿過 第二偏極分光鏡390而相互重合於一起而成為第四繞射光 165 ’此第四繞射光165經過45度角的第四偏振板gig而產 生Y方向的第四干涉光177，而由訊號處理裝置之第四 感測器790所接收。 因此，當訊號處理裝置700透過參考光感測器、第 一感測器730、第二感測為750、第三感測器770與第四感測 15 1270663 斋790而接收參考干涉光17〇、χ方向的第_干涉光I”、χ 方向的第二干涉光173、γ方向的第三干涉光m與γ方向的 第四干涉光m可量得二維光栅43〇二維移動時所產生的相 位差，便可經由此相位差而得出二維光柵·的二維移動。 π其中二維光柵係為反射式二維光柵或是亦有人稱閃 耀二維光栅，此光栅410係可用金屬薄膜或介電質薄膜所製 成’將此薄麟於玻璃基板祕基板，以形成具有週期性的 線距’而目前半導體製程技術其最小寬度約9〇奈米，所以當 光栅410的線距寬度越小時，其量測度精度越高。 同樣地，本實施例係選用二維的χ方向第一正一階繞射 光153、X方向第一負一階繞射光154、γ方向第一正一階繞 射光155與Υ方向第一負一階繞射光156，但是可根據不同 的量測範圍大小而選擇二維的不同階的繞射光，如二階或三 階等。 而上述的反射元件330b、330c可為反射鏡或直角稜鏡 等兀件’以使第一正一階繞射光153與第一負一階繞射光154 轉向而朝向第一偏極分光鏡37〇相互垂直的兩侧入射。另外 反射兀件330d、33〇e亦使第二正一階繞射光155與第二負 一階繞射光156轉向而朝向第二偏極分光鏡390相互垂直的 兩侧入射。 因為本實施例係沿用上一實施例光學架構，因為上一實 16 1270663 施例係針對—維的量_設計，而本實補絲示出此光學 架構尚可擴展為二維的制，所以其基本顧與優點不再贅 述。 、 以下就以一維量測光學架構而列出其量測數據，以資證 明本發明的效能與可行性。 睛麥閱「» 3 g」，所料本伽之帰與相位差關係 之數值模擬圖，我們再回想先前所提到的相位差公式： 卜，其中影響相位差的變數為繞射階數m、光柵410的 線距寬度d與光柵410移動&，若於使用相同的繞射階數m 與相同的光栅410移動心條件下，光栅41〇的線距寬度4可 直接景々響1測相位差的靈敏度，若光栅41〇的線距寬度d越 小的話，代表對位移越靈敏，所以由「第3圖」中可看到， 若光栅410的線距寬度(1為13000奈米（nm)時，其量測靈 敏度約為0.2227nm，而光柵410的線距寬度(1為1〇〇〇奈米 時，其量測靈敏度約為2· 88。/nm，若光柵410的線距寬度d 為600奈米時，其量測靈敏度約為4· 8。/·。反之，若以可 解析的最小相位量為〇·〇Γ為評比標準時，光柵41〇的線距 1度d為13000奈米時，可量得的最小位移量為4· 5χι〇_2奈 米’光柵410的線距寬度d為600奈米時，可量得的最小位 矛夕里為2· 1x10奈米。因此，光桃410的線距寬度d係影塑 里測精度甚矩’若欲置得較南精度的量測值時，便採用小線 17 1270663 距寬度的光柵410。 請參閲1第 回」，斤不為本發明之相位誤差量盥相對 t移誤差量之數簡_，當光學系統產生她量測誤差 %如偏振此合决差、二次諧波誤差或相位計算誤差等，對 位移的量測亦有—定程度的影響，由「第4圖」中可看出， 當相位誤差量由°。變化至G· 1。時，光栅的線距寬度為 6—00奈米時其位移誤差量為〇 〇21奈米，而光拇·的線距 寬度為1〇〇〇奈米時其位移誤差量為〇. 〇35，而奈米光拇· 的線距寬度為13000奈米時其位移誤差量為〇 451奈米，所 以在光栅410的線距見度為麵奈米以下且相位誤差在 ，時，可確保系統的最小量測誤差，即可量測魏具有次奈米 等級的位移解析度。 凊翏閱「第5圖」，所示為本發明之相位與位移量之數 值杈擬圖，此圖係表示在未使用相位延展技術（此站㊀ unwrapping)下可量得的最大量測距離，由「第5圖」中可 見得光柵410的線距寬度為13000奈米時，可量得的最大位 移1為3250奈米，而光栅410的線距寬度為1〇〇〇奈米與6〇〇 奈米時’可量得的最大位移量分別為250奈米與150奈米， 由此可知’本系統的一値量測周期約四分之一光柵410的線 距寬度。 17月茶閱「弟6圖」與「弟7圖」’所示為本發明之實際 18 1270663 量測數據圖’此量測值係使用光柵410的線距寬度為40000 奈米的光柵410，而「第β圖」係量測位移量結果，系統量 測的初始值由111·98奈米開始量測，最終之量測值為 587. 678奈米，所以實際量得的位移值係為475.698奈米， 為確保實驗的準確性，我們利用業界使用已久的位移量測儀 器：惠普（HP)公司所生產的ΗΡ5528Α干涉儀，以下簡稱為 ΗΡ5528Α，我們亦利用ΗΡ5528Α來同步量測，所量得之值為 495奈米，量測結果接近，另外在圖中5個圓圈處的最小位 移量值依座標軸相位量的增加方向分別為〇·4奈米、3奈米、 4奈米、10奈米及4奈米，相較於册552从僅能測出大於1〇 奈米的變化量，所以我們的量測精度係比ΗΡ5528Α再高一個 等級（order)。 而第7圓」係表示利用光柵41〇的線距寬度為4〇〇〇〇 奈米，且量測位移為18_奈米的圖*，共分三次量測，因 為18000奈米已超過一個位移周期，因每一個位移周期所對 應的相位係為度，所以當相位超過細度時，便會重新 由〇度開始’因此轉係有段差，而此_取部分的量測結 果，因量測三次，所以會有三個數據，其最後的量測結果如 下表： 19 1270663 本發明量測結果 HP5528A量測結果 實驗1 17. 754 17.8 貫驗2 18.462 18.5 貫驗3 17.514 17.8 因此’本發明之準共光程外差干涉位移量測系統經由數 值模擬與實際實驗結果可得知其量測精度與可容許誤差皆與 光柵410的線距寬度有關，若能採用較小的線距寬度則可提 回畺測精度’而且本發明之光學架構亦具有較高的環境變動 各心性，因此置測誤差小；並且本發明係量測相位，所以位 移對相位產生非連續變化，但配合相位延展技術，則可以量 測大位移距離之移動。 所以本發明之準共光程外差干涉位移量測系統具有次 奈米至皮米級的量測靈敏度，微米至奈米級的量測範圍，並 且可快速量測，光學架構簡單與容易模組化的設計，此外， 又不易受外在環境擾動的影響。 雖然本發明以前述之較佳實施例揚露如上，然其並非用 以限定本侧，任何熟習娜者，在獨離本發明之精 神和範圍内，當可作些許之更動與_，因此本發明之專利 保護顧馳本書所社申料種騎界定者為準。 【圖式簡單說明】 「第1圖」係顯示本發明之系統架構圖。 20 1270663 「第2圖」係顯示本發明之另一實施例系統架構圖。 「第3圖」係顯示本發明之位移與相位差關係之數值模擬圖。 「第4圖」係顯示本發明之相位誤差量與相對位移誤差量之 數值模擬圖。 「第5圖」係顯示本發明之相位與位移量之實際量測數據圖。 「第6圖」與「第7圖」係顯示本發明之實際量測數據示意 【主要元件符號說明】 100外差光源 110參考光 130信號光 150繞射光 151正一階繞射光 152負一階繞射光 153第一正一階繞射光 154第一負一階繞射光 155第二正一階繞射光 156第二負一階繞射光 160第一繞射光 161第二繞射光 163第三繞射光 21 1270663 165第四繞射光 170參考干涉光 171第一干涉光 173第二干涉光 175第三干涉光 177第四干涉光 300分光鏡 310第一偏振板 311第二偏振板 313第三偏振板 315弟四偏振板 317參考光偏振板 330、330a、330b、330c、330d、330e 反射元件 350偏極分光鏡 370第一偏極分光鏡 390第二偏極分光鏡 410光柵 430二維光柵 450移動平台 700訊號處理裝置 710參考光感測器 22 1270663 730第一感測器 750第二感測器 770第三感測器 790第四感測器The mirror 370 is reflected, and the p-polarization of the first negative first-order diffracted light 154 directly passes through the polarizing beam splitter 350 and coincides with each other to become the second diffracted light 161. The second diffracted light 161 passes through a 45-degree angle. The second polarizing plate 31i generates a second interference stop 73 in the X direction, which is received by the second sensor 750 of the signal processing device 7. The first-order first-order diffracted light 155 and the second negative first-order diffracted light 156 are also incident on the second polarized beam splitter 39〇 via the reflective elements 330d and 330e, and the two are perpendicular to each other. Side incidence, so that the P polarization of the first-order first-order diffracted light 155 passes, and the S polarization of the second negative first-order diffracted light 156 is reflected and coincides to become the third diffracted light ι63, the third diffracted light The third interference plate 175 in the gamma direction is generated by the third polarizing plate 313 at an angle of 45 degrees, and is received by the third sensor 770 of the signal processing device 700. The S polarization of the second positive first order diffracted light 155 is reflected by the second polarized beam splitter 390, and the p polarization of the second negative first order diffracted light 156 directly passes through the second polarized beam splitter 390 and coincides with each other. Together with the fourth diffracted light 165', the fourth diffracted light 165 passes through the fourth polarizing plate gig at an angle of 45 degrees to generate the fourth interfering light 177 in the Y direction, and is received by the fourth sensor 790 of the signal processing device. . Therefore, when the signal processing device 700 receives the reference interference light 17 through the reference light sensor, the first sensor 730, the second sensing 750, the third sensor 770, and the fourth sensing 15 1270663 790. The first interfering light I" in the x direction, the second interfering light 173 in the χ direction, the third interfering light m in the γ direction, and the fourth interfering light m in the γ direction can be measured when the two-dimensional grating 43 is moved two-dimensionally. The phase difference generated can be used to obtain the two-dimensional movement of the two-dimensional grating via the phase difference. π wherein the two-dimensional grating is a reflective two-dimensional grating or a blazed two-dimensional grating, the grating 410 is available. The metal film or dielectric film is made of 'this thin lining on the glass substrate to form a periodic line pitch' and the current semiconductor process technology has a minimum width of about 9 〇 nanometer, so when the line of the grating 410 The smaller the distance from the width, the higher the accuracy of the measurement. Similarly, in this embodiment, the first positive first-order diffracted light 153 in the two-dimensional χ direction, the first negative first-order diffracted 154 in the X direction, and the first γ direction are selected. The first-order diffracted light 155 and the first negative first-order diffracted light 156 in the Υ direction, but It is possible to select two-dimensional different orders of diffracted light according to different measurement range sizes, such as second-order or third-order, etc. The above-mentioned reflective elements 330b, 330c may be mirrors or right-angled 稜鏡, etc. A positive first-order diffracted light 153 and a first negative first-order diffracted light 154 are turned toward the mutually perpendicular sides of the first polarizing beam splitter 37. Further, the reflecting elements 330d, 33〇e also make the second positive first order The diffracted light 155 and the second negative first-order diffracted light 156 are turned toward the mutually perpendicular sides of the second polarizing beam splitter 390. Since this embodiment uses the optical structure of the previous embodiment, because the last real 16 1270663 embodiment It is designed for the dimension of the dimension, and the actual complement wire shows that the optical architecture can be expanded to a two-dimensional system, so its basic considerations and advantages will not be described. The following is a one-dimensional measurement optical architecture. The measurement data is used to prove the effectiveness and feasibility of the present invention. The eye is read "» 3 g", and the numerical simulation of the relationship between the gamma and the phase difference is expected. Let us recall the previously mentioned phase. Difference formula: Bu, which affects the phase difference The number is the diffraction order m, the line width d of the grating 410 and the grating 410 are moved & if the same diffraction order m is used and the same grating 410 is moved, the line width 4 of the grating 41〇 The sensitivity of the phase difference can be directly detected. If the line width d of the grating 41 is smaller, the more sensitive the displacement is, the "line 3" can be seen as the line width of the grating 410. (When 1 is 13,000 nanometers (nm), the measurement sensitivity is about 0.2227 nm, and the line width of the grating 410 (1 is 1 〇〇〇 nanometer, the measurement sensitivity is about 2. 88. / nm If the line width d of the grating 410 is 600 nm, the measurement sensitivity is about 4.8. /·. On the other hand, if the minimum phase amount that can be resolved is 〇·〇Γ as the evaluation standard, when the line distance of the grating 41〇 is 13000 nm, the minimum displacement that can be measured is 4·5χι〇_2 nm. When the line width d of the grating 410 is 600 nm, the smallest amount that can be measured is 2·1×10 nm. Therefore, the line width d of the light peach 410 is very accurate in the measurement. If a higher accuracy measurement is to be used, a small line 17 1270663 is used. Please refer to 1 first, "jin is not the phase error amount 为本 relative t shift error amount of the invention _, when the optical system produces her measurement error% such as polarization, the second harmonic error or The phase calculation error, etc., also has a certain degree of influence on the displacement measurement. It can be seen from "Fig. 4" that the phase error amount is °. Change to G·1. When the line width of the grating is 6-00 nm, the displacement error is 〇〇21 nm, and when the line width of the optical thumb is 1 〇〇〇 nanometer, the displacement error is 〇. 〇35 When the line width of the nano-light thumb is 13000 nm, the displacement error amount is 〇451 nm, so when the line-of-sight of the grating 410 is below the surface nanometer and the phase error is in, the system can be ensured. With the smallest measurement error, the displacement resolution of Wei with sub-nano grade can be measured. Referring to Figure 5, the numerical simulation of the phase and displacement quantities of the present invention is shown, which shows the maximum measurement distance that can be measured without using the phase extension technique (this station unwrapping). When the line width of the grating 410 is 13000 nm as seen in "Fig. 5", the maximum displacement 1 that can be measured is 3250 nm, and the line width of the grating 410 is 1 〇〇〇 nm and 6 At the time of 〇〇 nanometer, the maximum displacements that can be measured are 250 nm and 150 nm, respectively. It can be seen that the measurement cycle of the system is about one quarter of the line width of the grating 410. The 17th tea reading "Di 6 6 图 图" and "弟弟 7图" is shown as the actual 18 1270663 measurement data of the present invention. This measurement is a grating 410 using a grating 410 having a line width of 40,000 nm. The "β-graph" is the measured displacement result. The initial value of the system measurement is measured from 111.98 nm. The final measured value is 587. 678 nm, so the actual displacement value is 475.698 nm, in order to ensure the accuracy of the experiment, we use the industry's long-term displacement measuring instrument: Hewlett-Packard (HP) company's ΗΡ5528Α interferometer, hereinafter referred to as ΗΡ5528Α, we also use ΗΡ5528Α to measure simultaneously. The measured value is 495 nm, and the measurement results are close. In addition, the minimum displacement value at the five circles in the figure is 〇·4 nm, 3 nm, 4 nm, depending on the increase of the phase amount of the coordinate axis. 10 nm and 4 nm, compared to the book 552 can only measure the amount of change greater than 1 〇 nanometer, so our measurement accuracy is one level higher than ΗΡ5528Α. The 7th circle indicates that the line width of the grating 41〇 is 4〇〇〇〇N, and the displacement measured is 18_nm*, which is divided into three measurements because 18000 nm has exceeded one. The displacement period, because the phase corresponding to each displacement period is degree, so when the phase exceeds the fineness, it will start again from the enthalpy. Therefore, the system has a step difference, and the measurement result of this part is measured. Three measurements, so there will be three data, the final measurement results are as follows: 19 1270663 The measurement results of the invention HP5528A measurement results Experiment 1 17. 754 17.8 The inspection 2 18.462 18.5 The inspection 3 17.514 17.8 Therefore 'the invention The quasi-common optical path heterodyne interference displacement measurement system can be known through numerical simulation and actual experimental results that the measurement accuracy and allowable error are related to the line spacing width of the grating 410. If a smaller line spacing width can be used, The optical structure of the present invention also has a high environmental variation, and therefore the measurement error is small; and the present invention measures the phase, so the displacement produces a discontinuous change in phase, but the phase is matched. Extension technique, the mobile can measure the amount of displacement of the large distance. Therefore, the quasi-common optical path heterodyne interference displacement measuring system of the invention has the measurement sensitivity of the sub-nano to picometer level, the measurement range of the micrometer to the nanometer level, and can be quickly measured, and the optical architecture is simple and easy to mold. The grouped design, in addition, is not susceptible to external environmental disturbances. While the present invention has been described above in terms of the preferred embodiments described above, it is not intended to limit the present invention, and it is intended that the invention may be modified and modified within the spirit and scope of the invention. The patent protection of the invention is based on the definition of the species of the company. BRIEF DESCRIPTION OF THE DRAWINGS "FIG. 1" shows a system architecture diagram of the present invention. 20 1270663 "FIG. 2" is a system architecture diagram showing another embodiment of the present invention. Fig. 3 is a numerical simulation diagram showing the relationship between the displacement and the phase difference of the present invention. Fig. 4 is a numerical simulation diagram showing the phase error amount and the relative displacement error amount of the present invention. Fig. 5 is a graph showing the actual measurement data of the phase and displacement amount of the present invention. "Fig. 6" and "Fig. 7" show the actual measurement data of the present invention. [Main component symbol description] 100 heterodyne light source 110 reference light 130 signal light 150 diffracted light 151 positive first-order diffracted light 152 negative first order Diffractive light 153 first positive first order diffracted light 154 first negative first order diffracted light 155 second positive first order diffracted light 156 second negative first order diffracted light 160 first diffracted light 161 second diffracted light 163 third diffracted light 21 1270663 165 fourth diffracted light 170 reference interfering light 171 first interfering light 173 second interfering light 175 third interfering light 177 fourth interfering light 300 dichroic mirror 310 first polarizing plate 311 second polarizing plate 313 third polarizing plate 315 Four polarizing plate 317 reference light polarizing plate 330, 330a, 330b, 330c, 330d, 330e Reflecting element 350 polarizing beam splitter 370 First polarizing beam splitter 390 Second polarizing beam splitter 410 grating 430 Two-dimensional grating 450 mobile platform 700 Signal processing device 710 reference light sensor 22 1270663 730 first sensor 750 second sensor 770 third sensor 790 fourth sensor