β液體折射率的量測一直是化學工業上的一個重要課 題。例如，單純液體種類的辨識與混合液體成分的分析， 都可以由其折射率的量測來完成。為了滿足實驗或加工產 品的尚品質，必須要求液體折射率量測的高精罐度。而在 快速的生產線上，即時的量測系統變的更為重要。在一般 光學測量文獻中，有介紹利时涉儀【Κ3】^量液體折 射率的方法；雖然有报好的解析度，但是由於體積過於龐 大，而且又容易受到外界擾動的影響，所以干涉儀的方法 不適用於任何的場合，特別是在環境震動強烈的地方/ 在市售的液體折射率計中，以Abbe折射率計【4】 ^為常見。它主要的工作原理是根據幾何光學中的全反射 時之臨界角與SneU'slaw而來的，操作時需以望遠鏡或顯 微鏡來定出臨界角的位置。並用此臨界角推算出待測液體 折射率。另外，根據幾何光學原理所製成的折射率計還有 Pulfrich折射率計【4】，miger_Chance折射率計【*】 等。這些折射率計雖有體積小的優點，但是仍然有些缺點 存在. 1 ·由於需要做臨界角角度的量測’所以液體折射率的測 量精確度會受限於尺規的最小刻度。 2·由於它是測量光強度的關係，在測量全反射的臨界角 時，报容易受到環境背景光的干擾，所以必須在有遮 蔽或隔離其他不必要光源的情況下進行測量。同時它 也容易受到光源穩定度的影響。 本紙張尺度適财關家縣（CNS ) &4祕（21GX297公產） - 1— .1— · .------! (請先閱讀背面之注意事項再填寫本頁) 17 經濟部中央橾率局員工消費合作社印製 408220 五、發明説明（2 ) 3 .量測時需將待測液體移至儀器中 測。 無法做即時的量 經濟部中央標準局員工消費合作社印製 (二）發明概述 基於上述幾個方法的優缺點，本發明的目的除了要提 供一個體積小，精密度高的液體折射率計之外，並能符合 穩定、不受外界擾動、不受環境背景光的干擾、適用於各 種場合而且可以做即時的量測之要求。 本發明最重要部份是探頭模組的設計，它包含有一高 折射率的玻璃材料所做成等腰梯形體稜鏡，一個半反射 鏡、一個反射鏡、兩個檢偏板與兩個偵測器所構成的模組 裝置。當一外差光源【5】入射此一模組時，首先被分光 鏡分成反射光與透射光二部份；反射光經第一個檢偏板之 後’進入偵測器，以此偵測器的輸出信號為參考信號。另 一方面，穿透光垂直進入等腰梯形體稜鏡。光線在稜鏡的 腰面與底面會有三次固定角度的全反射，此時與稜鏡的兩 個腰面與底面接觸的介質為空氣。光線垂直離開稜鏡後， 經反射鏡而通過另一個檢偏板，再被另一個偵測器所接 收。此時所接收到的信號為測試信號。將參考信號與測試 L號送入相位計可得一初始相位差。接著使等腰梯形體稜 鏡的底面與待測液體接觸。由於與稜鏡底面的全反射面接 觸的介質改變之故，所以相位差也跟著改變。接著由相位 计直出待測液體所引起的相位差的變化量，並將此相位差 變化量代入由菲涅爾方程式所推演出的公式中，由片 本紙張尺度標^7—)鐵格（2lGx^^ (請先閲讀背面之注項再填寫本頁) ---Φ裝· -.可 線. 經濟部中央標準局員工消費合作社印製 408220 A7 __B7__ 五、發明説明（3 ) 計算出待測液體的折射率，且以數位顯示器顯示出來，方 便讀取。 (三）發明的詳細說明 為說明本發明之工作原理，現以較佳之實施例配合附 圖之說明敘述如後，其中： 圖一為本發明之折射率計的結構圖。 圖二為本發明折射率計模組中的等腰梯形體稜鏡之幾何 形狀。 本折射率計系統的主要結構（參閱圖一）係由下列幾 項元件所組成： 1 1 : 一個外差光源（heterodyne light source );亦即 s (垂直）偏光與p (水平）偏光間有頻差/的雷射光源； 12 :搞合透鏡（coupling lens ); 13 :偏光保持光纖（polarization maintaining fiber ); 14 :準直透鏡（collimating lens )； 15 :探頭模組（probe module ); 151 :分光鏡（beam-splitter ); 152、153 :透光軸在45。方向的檢偏板（analyzer ); 154、155 :光侦測器（photodetector ); 1 56 :等腰梯形體棱鏡（isosceles trapezoid prism )； 157 :反射鏡（mirror ); 16 :相位計(phase meter ) > 本紙張尺度適用中國國家標準（CNS ) A4规格（210X297公釐} ---：.------{ 裝---„---許--，--7—" .線 IVV (請先閲讀背面之注意事項再填寫本頁) 408220 Α7 Β7 經濟部中央標準局I工消費合作社印製 五、發明説明（4 ) 17 :單晶片（chip ); 18 :數位顯示器（digital display )。 首先由外差光源1 1所射出之光線經耦合透鏡12導入 偏光保持光纖13中傳導。再由準直透鏡[4將光線準直， 並且入射探頭模組15。接著光線被分光鏡15ι分成反射 光與透射光二部份；反射光經檢偏板152之後，s偏光與p 偏光在45方向的分量互相干涉，然後再由光偵測器1 54 取出干涉信號，以此偵測器的輸出信號為參考信號，它是 頻率為外差光源差頻的正弦波信號，我們將它設為八，則 ’r可寫為 臺[1 + 咖(2硪 +也)]’ （1 ) 而相位夾為s偏光與p偏光間經分光鏡1 5丨反射後所引起 的相位差。 另一方面’穿透光則垂直射入等腰梯形體稜鏡156。 在等腰梯形體稜鏡中（參閱圖二）光線在稜鏡的腰面21、 底面22與腰面23各進行一次入射角為固定角（6〇。）的 全反射後’垂直離開稜鏡；而此時與全反射介面所接觸的 介質為空氣。光線離開稜鏡後’由反射鏡15?反射而通過 檢偏板153;同樣地’ 3偏光與卩偏光也在45。方向的分 置互相干涉’然後再由光偵測器1 5 5取出干涉信號，以此 谓測器的輸出信號為測試信號，它也是頻率為外差光源差 頻的正弦波信號，我們將它設為/1，則/丨可寫為 本紙張尺度適财_家縣（⑽）Λ4规格（2ΐ()χ297公楚） ---U------ίο-裝---^---訂-----Ί,線 (請先閲讀背面之注意事項再填寫本頁) 408220 經濟部中央標準局員工消費合作社印製 A7 B7 五、發明説明（5 ) 4 =封1 + c〇s(2峨 ϋ)]， ( 2 ) 而相位七為s偏光與ρ偏光間在稜鏡中Β、〇與1?三處全 反射後所引起的相位差的和’相位為s偏光與ρ偏光 反射鏡15 7所引起的相位差。然後將參考信號與測試作號_ 送入相位計16之後，可將兩信號的相位差+ ^測量 出來。接著將等腰梯形體稜鏡1 56的底面22接觸待測液 體。由於與稜鏡底面的全反射面接觸的介質改變，所以測 試信號變成為 /2=|[l + cos(2碘 + 么 + 釦)]， (3 ) 而相位和為底面22與待測液體接觸後，s偏光與p偏光 間在稜鏡中B、D與F三處全反射所引入的相位差的和。 此時相位計所測量出的相位差變為（朽+ ίΖ>Μ_化）。將 (Hm-A )及（iZ>2+0M-《r )值送入單晶片中，可以計 算出接觸液體前後的相位差變化量為（#2_化）之值。並 將此相位差變化量的值代入由菲涅爾方程式所推演岀的 么式中’由單晶片計算出待測液體的折射率，且以數位顯 示器顯示出來。 為了推導出相位差變化量（02_化）與待測液體折射率 間的關係，我們以圖二來說明D圖二是本發明模組中的重 要結構，它是一個由已知折射率為的玻璃材料所做成 等腰梯形體稜鏡，它的四個内角分別為之AGE = Z GAC = 60。，/ ACE=z： CEG=120。。稜鏡的 AG 界面 本紙張尺度適用+國國家標準（CNS )八4祕（2i0xl97公釐了 (請先閲讀背面之注意事項再填寫本頁) ---裝---,---訂--.--1."線--- A7 B7 408220 五、發明説明（6 ) 與CE底面互為平行，外差光源垂直入射於AG界面而進 入稜鏡中，由於Z ACE=Z CEG=120 °的設計，使光線到 達稜鏡中的B、D與F三處時的入射角都大於臨界角，其 入射角均為60° ，而產生全反射。最後經F全反射之光 與入射光逆平行，垂直通過AG界面而離開稜鏡。由於在 B、D與F三處發生全反射，會使得8偏光與p偏光間有 相位差產生。當此稜鏡的CE底面未與待測液體接觸時， 出射光的S偏光與P偏光間的相位差，由菲涅爾方程式 C Fresnel’s equation )【6 】計算得 φί=φΒ+φΏ+φΐ= 2>ψΒ 4 {請先閲讀背面之注意事項再填寫本頁) --------,— — —1 — .The measurement of the refractive index of β liquid has always been an important subject in the chemical industry. For example, identification of pure liquid types and analysis of mixed liquid components can be accomplished by measuring their refractive index. In order to meet the high quality of experimental or processed products, high precision cans of liquid refractive index measurement must be required. On fast production lines, the instant measurement system becomes more important. In the general optical measurement literature, there is a method for measuring the refractive index of liquids [K3] ^; although there is a good resolution, but because the volume is too large, and it is easily affected by external disturbances, the interferometer The method is not suitable for any occasion, especially in places with strong environmental vibrations / in the commercially available liquid refractive index, Abbe refractive index [4] ^ is common. Its main working principle is based on the critical angle of total reflection in geometrical optics and SneU'slaw. The position of the critical angle needs to be determined by a telescope or microscope in operation. And use this critical angle to calculate the refractive index of the liquid to be measured. In addition, the refractometers made according to the principles of geometric optics include Pulfrich refractometer [4], miger_Chance refractometer [*], and so on. Although these refractive index meters have the advantages of small volume, they still have some disadvantages. 1 · Because the critical angle angle measurement is needed, the measurement accuracy of liquid refractive index will be limited by the minimum scale of the ruler. 2. Since it is a measurement of light intensity, when measuring the critical angle of total reflection, the signal is susceptible to interference from ambient background light, so it must be measured under the condition of shielding or isolating other unnecessary light sources. It is also easily affected by the stability of the light source. This paper is suitable for Guancai County (CNS) & 4 secrets (21GX297)-1— .1— · .------! (Please read the notes on the back before filling out this page) 17 Ministry of Economy Printed by the Central Government's Bureau Consumer Cooperatives 408220 V. Description of Invention (2) 3. The liquid to be measured must be moved to the instrument for measurement. Cannot be printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economics (2) Summary of the invention Based on the advantages and disadvantages of the above methods, the purpose of the present invention is to provide a liquid refractive index meter with small size and high precision And it can meet the requirements of stability, no external disturbance, no interference from ambient background light, suitable for various occasions, and real-time measurement. The most important part of the present invention is the design of the probe module, which includes an isosceles trapezoid made of a glass material with a high refractive index, a half mirror, a mirror, two analyzers, and two detectors. Modular device made up of measuring devices. When a heterodyne light source [5] enters this module, it is first divided into two parts: reflected light and transmitted light by the beam splitter; the reflected light enters the detector after passing through the first analyzer plate, and the detector ’s The output signal is a reference signal. On the other hand, the penetrating light enters the isosceles trapezoid 稜鏡 vertically. The light will have three total reflections at a fixed angle between the waist and the bottom of the chestnut. At this time, the medium that is in contact with the waist and the bottom of the chestnut is air. After the light leaves vertically, it passes through the mirror and passes through another analyzer, and is received by another detector. The signal received at this time is a test signal. Send the reference signal and test L number to the phase meter to get an initial phase difference. Then the bottom surface of the isosceles trapezoidal prism is brought into contact with the liquid to be measured. The phase difference also changes because the medium in contact with the total reflection surface of the base is changed. Then the phase meter directly calculates the amount of phase difference caused by the liquid to be measured, and substitutes this amount of phase difference into the formula derived from the Fresnel equation. (2lGx ^^ (Please read the note on the back before filling out this page) --- Φ Packing ·-. Available. Printed by the Staff Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs 408220 A7 __B7__ V. Description of the invention (3) Calculated The refractive index of the liquid to be measured is displayed on a digital display for easy reading. (3) Detailed description of the invention In order to explain the working principle of the present invention, the preferred embodiment will be described below with the description of the drawings, where: Figure 1 is a structural diagram of the refractive index meter of the present invention. Figure 2 is the geometric shape of an isosceles trapezoid in the refractive index module of the present invention. The main structure of the refractive index system (see Figure 1) consists of It consists of the following components: 1 1: a heterodyne light source; that is, a laser light source with a frequency difference / s between a s (vertical) polarization and a p (horizontal) polarization; 12: a coupling lens lens); 13: Polarized light (Polarization maintaining fiber); 14: collimating lens; 15: probe module; 151: beam-splitter; 152, 153: analysis with the transmission axis at 45. Analyzer; 154, 155: photodetector; 1 56: isosceles trapezoid prism; 157: mirror; 16: phase meter > Paper size applies to China National Standard (CNS) A4 (210X297 mm) ---: .------ {装 --- „--- 许-, --7— ". 线 IVV ( Please read the precautions on the back before filling in this page) 408220 Α7 Β7 Printed by I Industrial Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs 5. Description of the invention (4) 17: single chip (chip); 18: digital display (digital display). First, the light emitted by the heterodyne light source 11 is introduced into the polarization maintaining fiber 13 through the coupling lens 12 and then transmitted by the collimating lens [4, which collimates the light and enters the probe module 15. Then, the light is divided into reflections by the beam splitter 15m. Light and transmitted light; after reflected light passes through the analyzer 152, s-polarized light and p-polarized light The components in the 45 direction interfere with each other, and then the interference signal is taken out by the light detector 1 54. The output signal of the detector is used as a reference signal. It is a sine wave signal with a frequency that is the difference frequency of the heterodyne light source. We set it Is eight, then 'r can be written as a stage [1 + coffee (2 硪 + also)]' (1) and the phase clamp is the phase difference caused by the s-polarized and p-polarized light reflected by the beam splitter 15 5. On the other hand, the 'penetrating light' enters the isosceles trapezoid 稜鏡 156 vertically. In an isosceles trapezoidal ridge (see Figure 2), the light leaves the ridge's waist surface 21, bottom surface 22, and waist surface 23 each after a total reflection at a fixed angle (60 °). ; At this time, the medium in contact with the total reflection interface is air. After the light exits the beam, it is reflected by the mirror 15? And passes through the analyzer 153; similarly, the 3 polarized light and the chirped light are also 45. The separation of the directions interfere with each other ', and then the interference signal is taken out by the light detector 1 5 5. This is called the output signal of the detector as the test signal. It is also a sine wave signal with a frequency of the heterodyne light source. Set to / 1, then / 丨 can be written as the paper size suitable for money_ 家 县 （⑽） Λ4 Specification (2ΐ () χ297 公 楚) --- U ------ ίο- 装 --- ^- --Order ----- Ί, line (please read the notes on the back before filling out this page) 408220 Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs A7 B7 V. Description of the invention (5) 4 = Seal 1 + c 〇s (2Emei)], (2) and phase seven is the sum of the phase differences caused by total reflection between s-polarized light and ρ-polarized light at three B, 0, and 1? The phase difference caused by the p-polarizing mirror 15 7. After sending the reference signal and test number _ to the phase meter 16, the phase difference between the two signals + ^ can be measured. Then, the bottom surface 22 of the isosceles trapezoid 稜鏡 1 56 is brought into contact with the liquid to be measured. Due to the change of the medium in contact with the total reflection surface of the tritium bottom surface, the test signal becomes / 2 = | [l + cos (2 iodine + Mo + buckle)], (3) and the phase sum is the bottom surface 22 and the liquid to be measured After the contact, the sum of the phase differences introduced by total reflection at three points B, D, and F between s-polarized light and p-polarized light. At this time, the phase difference measured by the phase meter becomes (朽 + ίZO & M_ 化). By sending the values of (Hm-A) and (iZ> 2 + 0M- <r) to a single chip, the amount of change in phase difference before and after contact with the liquid can be calculated as (# 2_ 化). And the value of this phase difference change amount is substituted into the formula deduced from the Fresnel equation ', the refractive index of the liquid to be measured is calculated from a single chip, and displayed by a digital display. In order to deduce the relationship between the amount of change in phase difference (02_) and the refractive index of the liquid to be measured, we will use Figure 2 to illustrate D. Figure 2 is an important structure in the module of the present invention. The isosceles trapezoid 稜鏡 made of glass material has four internal angles of AGE = Z GAC = 60. , / ACE = z: CEG = 120. .稜鏡 AG interface This paper size applies + National National Standard (CNS) 8 4 secrets (2i0xl97 mm) (Please read the precautions on the back before filling this page) --- --- ---, --- -.-- 1. &Quot; Line --- A7 B7 408220 V. Description of the invention (6) is parallel to the bottom surface of CE, and the heterodyne light source enters the interface perpendicular to the AG interface and enters the radon, because Z ACE = Z CEG = The design of 120 ° makes the angle of incidence when the light reaches the three points B, D and F in the frame is greater than the critical angle, and the angle of incidence is 60 °, resulting in total reflection. Finally, the light and incident that are totally reflected by F The light is antiparallel and leaves the 稜鏡 perpendicularly through the AG interface. Since total reflection occurs at B, D, and F, a phase difference between 8-polarized and p-polarized light will be generated. When the 稜鏡 's CE bottom surface is not equal to the test The phase difference between the S-polarized light and the P-polarized light when the liquid comes into contact is calculated from Fresnel's equation C Fresnel's equation) [6] φί = φΒ + φΏ + φΐ = 2 > ψΒ 4 {Please read the note on the back first Please fill in this page for matters) --------, — — — 1 —.
：6tan' i^L· 2 3 3 UpJ 經濟部中央標準局員工消費合作社印製 而與办分別是在B、D與F三處全反射時所引 起s偏光與p偏光間的個別相位差。由於入射角皆為 6〇。 ’而且介面介質皆相同，所以知=知=知。當稜鏡的 底面CE面與待測液體接觸時，設待測液體折射率為”， 則出射光的S偏光與p偏光間的相位差為 厶=卢B +呢+各=2念+羝 ：4tan~l λ/Ϊ ί】_4 Γη2 V«p.: 6tan 'i ^ L · 2 3 3 UpJ Printed by the Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs. Because the angle of incidence is 60. ’And the interface medium is the same, so I know = know = know. When the bottom CE surface of 稜鏡 is in contact with the liquid to be measured, set the refractive index of the liquid to be measured to be ", then the phase difference between the S-polarized light and the p-polarized light of the outgoing light is 厶 = Lu B +? + Each = 2 羝 + 羝: 4tan ~ l λ / Ϊ ί] _4 Γη2 V «p.
> + 2tan、 / \ 2 ,4 n i-- ；> 3 UpJ 而A為底面CE與待測液體接觸時，S D處全反射時户 引起s偏光與p偏光間的相位差。則由（4 ) ，（ $ ) ^ 可以得到待測液體所引入的相位差變化量為 " 訂 Ί、,€·_ &張尺度適用中_家鱗（CNS) Α4·(训“公酱_ 6408220 Α7 Β7 五、發明説明（7 ) έ,φ = φ2-φι = φ'Ώ-φΏ 2tan" 4 βρ)> + 2tan, / \ 2, 4 n i--; > 3 UpJ When A is the bottom surface and CE is in contact with the liquid to be measured, the phase difference between s-polarized light and p-polarized light is caused by total reflection at SD. From (4) and ($) ^, we can get the amount of phase difference change introduced by the liquid to be measured is " Ί ,, € · _ & Zhang scales are applicable _home scale (CNS) Α4 · (training "public Sauce _ 6408220 Α7 Β7 V. Description of the invention (7), φ = φ2-φι = φ'Ώ-φΏ 2tan " 4 βρ)
*2 tan~V % 經濟部中央標準局員工消費合作社印製 6 )式可以改寫為 1 3-9tan2 tan-1 +銼1 2 1113 Η) 2 由（7 )式可知，在《ρ已知的情況下，若能準確的測出底 面CE接觸液體前後的相位差變化量值，即可準轉得到 待測液體折射率《。 本發明疋基於全反射所引起的相位差變化之原理來測 量液體的折射率，所以光線在稜鏡中必須滿足全反射的條 件。由於本發明中稜鏡的特殊設計使全反射角固定為 60 ’在滿足全反射條件的情況下，待測液體折射率與 稜鏡折射率的關係為： ' n = «psin60°=^«p， ⑻ 也就是說待測液體折射率的可測量範圍會受到稜鏡折射 率的限制。為了使測量的範圍夠大’必須選擇折射率較高 的玻璃作為稜鏡的材料。以常用的SF11玻璃為例，在 He-Ne雷射632.8nm的波段，其折射率為} _77862。根據 (8 )式’可知可測到液體最大的折射率約為ι ·5 ;也就 是說’折射率在i至i 5範圍的液體都可以被測量到。此 範圍已經可以滿足大多數的液體了。 ---；------裝--------訂--.. {請先閱讀背面之注意事項再填寫本頁j '線--- 經濟部中央標準局員工消費合作社印製 408220 A7 ---____五、發明説明（8 ) 本發明中的光學元件，包括分光鏡、等腰梯形體稜鏡、 反射鏡、檢偏板與光偵測器，可以組裝成一個小體積的探 頭硬體模組。再用偏光保持光纖（p〇larizati〇n maintaining fiber )將外差光源引入此模組中。如此可以方便地移動 探頭硬體模組。由於此為一個共光程外差干涉系統，所以 測量相位差變化的結果不受光源強度穩定與否的影響，同 時也可以克服外界震動與雜散光的干擾等優點。 唯上述實施例僅為說明本發明之原理及其功效，而非 限制本發明之範圍，因此，習於此藝之人士對上述實施例 所做之修改及變化仍不違背本發明之精神。本發明之權限 應如後述之申請專利範圍所列。 (請先閲讀背面之注意事項再填寫本頁) ------r---^---------^----ΤΓ--.--1--- ..^1.—— 本紙浪尺度適用中國國家標準c CNS ) A4規格（210·Χ297公釐） 408220 A7 B7 五、發明説明（9 ) 檢索資料 1. J. M. St-Arnaud, J. Ge, J. Orbriot and T. K. Bose, MAn accurate method for refractive index measurements of liquids using two Michelson laser interferometers, n Rev. Sci. Instrum. 62(6), 14 1 1 -1 41 4, (1991). 2. T. Li. and X· Tan, "Stepwise interferometric method of measuring the refractive index of liquid samples, n Appl. Opt. 32(13), 2274-2277, (1993). 3. E. Moreels, C. de Greef, and R. Finsy, "Laser light refractometer, ,f Appl. Opt. 23(17), 3010-3013 (1984). 4. R. S. Longhurst, ^Prismatic instruments for refractometry and spectroscopy, " Chap. 5 in Geometrical and Physical Optics, 3rd ed, pp. 82-99, Longman Inc., New York, (1973). 5. D. C. Su, Μ. H. Chiu, and C. D. Chen, ^Simple two-frequency laser, w Prec. Eng. 18, 161-163 (1996). 6. M. Born and E. Wolf, Principles of Optics, 6th ed, pp.40, Pergamon Press, Oxford, Uk, (1980). ---r-------- {請先閱讀背面之注意事項再填寫本頁)* 2 tan ~ V% Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 6) The formula can be rewritten as 1 3-9tan2 tan-1 + file 1 2 1113 Η) 2 From formula (7), we can see that In the case, if the amount of phase difference change before and after the bottom surface CE contacts the liquid can be accurately measured, the refractive index of the liquid to be measured can be obtained in a quasi-rotation. In the present invention, the refractive index of a liquid is measured based on the principle of the phase difference change caused by total reflection, so the light must meet the conditions of total reflection in the light. Due to the special design of ytterbium in the present invention, the total reflection angle is fixed at 60 '. Under the condition that the total reflection conditions are satisfied, the relationship between the refractive index of the liquid to be measured and the ytterbium refractive index is:' n = «psin60 ° = ^« p , ⑻ In other words, the measurable range of the refractive index of the liquid to be measured will be limited by the refractive index of 稜鏡. In order to make the measurement range sufficiently large, it is necessary to select a glass with a higher refractive index as the material of the rubidium. Taking the commonly used SF11 glass as an example, the refractive index of He-Ne laser at 632.8nm is} _77862. According to formula (8) ', it can be known that the maximum refractive index of the liquid that can be measured is about ι · 5; that is, any liquid whose refractive index is in the range of i to i 5 can be measured. This range is already sufficient for most liquids. ---; ------ installed -------- order-.. {Please read the notes on the back before filling in this page j 'line --- Staff Consumer Cooperatives, Central Standards Bureau, Ministry of Economic Affairs Printed 408220 A7 ---____ V. Description of the invention (8) The optical elements in the present invention, including a beam splitter, isosceles trapezoid, a reflector, an analyzer and a light detector, can be assembled into one Small size probe hardware module. A polarizing maintaining fiber (pollarization maintaining fiber) is used to introduce the heterodyne light source into this module. This makes it easy to move the probe hardware module. Since this is a common optical path heterodyne interference system, the result of measuring the phase difference is not affected by the stability of the light source intensity, and it can also overcome the advantages of external vibration and stray light interference. The above embodiments are only for explaining the principle of the present invention and its effects, but not for limiting the scope of the present invention. Therefore, modifications and changes made by those skilled in the art to the above embodiments still do not violate the spirit of the present invention. The rights of the present invention should be listed in the patent application scope mentioned later. (Please read the precautions on the back before filling this page) ------ r --- ^ --------- ^ ---- ΤΓ --.-- 1 --- .. ^ 1 .—— The paper scale is applicable to the Chinese national standard c CNS) A4 specification (210 · × 297 mm) 408220 A7 B7 V. Description of the invention (9) Retrieval information 1. JM St-Arnaud, J. Ge, J. Orbriot and TK Bose, MAn accurate method for refractive index measurements of liquids using two Michelson laser interferometers, n Rev. Sci. Instrum. 62 (6), 14 1 1 -1 41 4, (1991). 2. T. Li. and X. Tan, " Stepwise interferometric method of measuring the refractive index of liquid samples, n Appl. Opt. 32 (13), 2274-2277, (1993). 3. E. Moreels, C. de Greef, and R. Finsy, " Laser light refractometer,, f Appl. Opt. 23 (17), 3010-3013 (1984). 4. RS Longhurst, ^ Prismatic instruments for refractometry and spectroscopy, " Chap. 5 in Geometrical and Physical Optics, 3rd ed, pp. 82-99, Longman Inc., New York, (1973). 5. DC Su, Μ H. Chiu, and CD Chen, ^ Simple two-frequency laser, w Prec. Eng. 18, 161 -163 (1996). 6 M. Born and E. Wolf, Principles of Optics, 6th ed, pp.40, Pergamon Press, Oxford, Uk, (1980). --- r -------- {Please read the note on the back first (Fill in this page again)
1T 經濟部中央標準局員工消費合作社印製 本紙浪尺度適用中國國家標率（CNS > M規格（210χ297公釐）1T Printed by the Consumer Cooperatives of the Central Bureau of Standards of the Ministry of Economic Affairs This paper scale is applicable to China's national standard (CNS > M specification (210 × 297 mm)