201041327 六、發明說明： 【發明所屬之技術領域】 本發明關於一種光纖感測系統，尤指一種利用測量反 射光能量取代測量波長漂移之回音廊模態解調式光纖光栅 感測系統。 【先前技術】 近年來國内光纖感測器（Fiber Optic Sensor)的研究領 ^ 域已引起注目’光纖感測器具有微小化、輕量化、能在惡 劣環境下操作、不受電磁干擾及生物相容性良好等優點， 尤其光纖之直徑約為1 25 // m，遠小於現有已商品化之感 測器。 目前大多數光纖相關之感測器可見諸於本國及國外之 專利中請，諸如本國專利公告號：585998、1229751、 I226436 、 I225923 、 579445 、 1232315 、 574510 等；美 國專利如 7043115 、 7418171 、 7424178 、 7391942 、 7092591^6987914^6891997^7336861^7379632^7379169 等i由上述所提及之内容可知，目前大多數光纖感測器之 :究，應帛’主要利用因溫度、應變、壓力所產生之波長 /不移里（短週期光纖光栅FBG反射頻譜及LpG長週期光 纖光柵穿透頻譜之波長漂移）來監測相關物理量之變化， 係屬於頻·解調式感測器，一般均需利用昂貴之儀器及複 雜的實驗架構進行波長漂移之量測。&了檢測設備之問題 卜對於動態物理量之量測，亦非常困難。 3 201041327 【發明内容】 由上述S兒明可知，—般藉測量波長漂移方式監測相關 物理量變化的光纖感測器，需利用昂貴儀器及複雜的實驗 架構進仃波長漂移之量測，且對於動態物理量之量測，亦 非常困難。 有馨於此，本發明之主要目的在於提供一種回音廊模 態解調式光纖光栅感測系統，係為相較於先前技術具低成 本、可動態量測之光纖感測系統。 欲達上述目的所使用之技術手段，係令該回音廊模態 解調式光纖光柵感測系統包含： —感測元件’係用以接觸一待測端而感應待測端所產 生的物理變化； 一光纖耦合器，係連接該感測元件；及 反射flb $監測系統，係連接該光纖柄合器並包含一 光纖環作為解調元件’該反射能量監測系統係輸出光線而 0 經由該光纖耦合器傳遞至該感測元件，並接收從感測元件 反射回光纖耦合器的光線，藉由其光纖環使反射光線產生 回音廊模態（Whispering Gallery Mode)干涉以進行解調， 進而探測反射光能量變化量而對應測出該待測端之物理變 化量。 本發明之光纖感測器主要利用測量反射光能量取代測 量波長漂移之方式，將可有效減少設備成本及簡化實驗架 構；同時建構適合靜態與動態壓力之量測系統，因具有成 本低、體積小等優勢，將可廣泛應用於航太科技、土木工 程、汽車交通、精密機械等工業領域。 4 201041327 【實施方式】 請參考第一圖所示，係本發明回音廊模態解調式光纖 光柵感測系統一較佳實施例之示意圖，係包含： 一感測元件（1 〇)’係用以接觸一待測端，可量測待測 端所產生的物理變化’如溫度、應變、壓力，其可為一光 纖布拉格光栅（FBG)感測器； 一光纖耦合器（20)，係連接該感測元件（1〇); 一反射能量監測系統（30)，係連接該光纖耦合器（2〇) 並具有一光纖環（31)作為解調元件，本實施例中，該反射 月b i監測系統（3 0)係輸出光線而經由該光纖搞合器（2 〇)傳 遞至該感測元件（10)，並接收從感測元件（1〇)反射回光纖 耦合器（20)的光線，藉由該光纖環（31)使反射光線產生回 音廊模態（Whispering Gallery Mode)之破壞性干涉以進行 解調，進而探測反射光能量變化量而測出該待測端之物理 變化量。 前述解調方式係利用彎曲的光纖所產生之回音廊模態 (Whispering gaMery，WG)干涉模態做為基礎當光線在^ 曲的光纖中傳遞時，有部分光線從纖核傳至纖殼，在纖般 與空氣介面反射後而再次麵合回纖核中，與原先傳遞於纖 核内的光線產生干涉頻譜。 本實施例中，該反射能量監測系統（3〇)尚包含一光源 產生裝置（32)及-光接收器（33)。其中該光源產生襄置（32) 係連接該光_合器（2〇)以輸出光線至該光纖耗合器（2〇); 該光接收11(33)可為-光電：極體，其係連接該光纖環（31) 5 201041327 ' 以接收從感測元件（10)反射回光纖耦合器（20)的光線，並 將光能量轉換成電歷訊號，根據此電壓訊號即可分析待測 端之物理變化量。 °月參考第二圖所示，本感測系統於操作前須先進行校 ^以調整欲進行量測的渡波特性，亦即決定光能量的㈣ 範圍（Dynam丨c Range) ’是以，先令前述作為解調元件用 之光纖環（31)兩端水平地分別固定於兩平移台（4〇)上並 使该光纖環（31)兩端分別連接一光源產生裝置（5〇)及一光 譜分析儀_，令該光源產生裝置（4〇)輸出光線，經由光 纖環（31)傳遞至光譜分析儀光譜分析儀⑽）即可顯示 光線能量變化曲線之頻譜圖。 由於光線經過光纖環（31)時會因回音廊模態干涉的關 係，使得部分波長的光能量損失而在頻譜圖上呈現一衰減 波段_e_ti〇n Band)，此時藉由調整兩平移台_之間 的遠近距離改變錢環（31)的半徑，進而改變光干涉情形， 可使得光譜分析儀（7〇)顯示不同笋、占、*外& θ Ο 门农減波奴的迠$變化曲線 的頻5曰圖，如附件一所示， 對之光能量變化與波長變化，2不同+徑下农減波段相 跫化斜率小而範圍廣的波段，可 測的波長變化範圍大；斜率 ,,,Μ „ 旱大而範圍窄的波段，則可測的 波長變化乾圍小但較為靈敏。 由此可知，改變光纖環（31) 之+徑即可改變本系統所欲 机一加、、^ 、 ®測之光能量動態範圍’相較 ;一般濾波器的濾波特性 的量測手段。 L周整，本系統則提供更靈活 當決定光纖環（31)之半庐銘 量動態範圍的調整，如附二，即完成所欲量測之光能 t〜所示，在此動態範圍内感測 6 201041327 元件（10)受到應變能量遞增所造成光傳遞的波長漂移，將 可反應在光能罝的變化。又由於光能量可透過前述光接收 器（33)轉為電m因此藉由量测㈣值的大小對比量 測感測元件（1〇)受到的應力變化，即可得出如附件三所示 的應變&正® m统實際進行操作時應力變化的參考 依據。除了測量應變之外，溫度錢力等相關對應之數值 亦可由此方式得出。 本發明於實際操作時，可令感測元件（1 〇)接觸一待測 端:例如將感測元件（Μ埋設於橋樑或建築結構體中，經 由光的傳輸與反射而由該反射能量監測系統（3〇)的光接收 时（33)廉，則電壓（亦即監測光能量變化），當橋樑結構產生 應力變化時’即可相對從電壓變化得知應變程度。 综上所述，本發明主要利用測量反射光能量取代測量 波長漂移之方透過相_能量的監冑’間接推導出所要 里測的物理s大小，將可有效減少設備成本及簡化實驗架 構，同時建構適合靜態與動態壓力之量測系統，且恃其成 本低、體積小等優勢，將可廣泛應用於航太科技、土木工 程、汽車交通、精密機械等工業領域。 【圖式簡單說明】 第一圖：係本發明一較佳實施例之示意圖。 第一圖：係本發明一較佳實施例之校正示意圖。 附件一：係本發明之不同的能量變化曲線的頻譜圖。 附件二：係透過本發明光纖環解調後之布拉格光柵應 變頻譜圖。 〜 7 201041327 . 附件三：係本發明之光接收器的應變校正圖。 【主要元件符號說明】 (10)感測元件 （20)光纖耦合器 (30)反射能量監測系統（31)光纖環 (32)光源產生裝置 （33)光接收器 (40)平移台 （50)光源產生裝置 (60)光譜分析儀 〇201041327 VI. Description of the Invention: [Technical Field] The present invention relates to an optical fiber sensing system, and more particularly to an anechoic mode demodulation fiber grating sensing system that uses measurement of reflected light energy instead of measuring wavelength drift. [Prior Art] In recent years, the research field of domestic Fiber Optic Sensor has attracted attention. 'The fiber optic sensor is miniaturized, lightweight, can operate in harsh environments, is free from electromagnetic interference and biological The compatibility is good, especially the diameter of the fiber is about 1 25 // m, which is much smaller than the existing commercially available sensors. At present, most of the fiber-related sensors can be found in domestic and foreign patents, such as national patent announcement numbers: 585998, 12297751, I226436, I225923, 579445, 1232315, 574510, etc.; US patents such as 7043115, 7418171, 7424178 7,391942, 7092591^6987914^6891997^7336861^7379632^7379169, etc. As can be seen from the above mentioned content, most of the current fiber optic sensors are: mainly used due to temperature, strain and pressure. Wavelength/immoval (short-period fiber grating FBG reflection spectrum and wavelength drift of LpG long-period fiber grating penetration spectrum) to monitor changes in related physical quantities, belonging to frequency demodulation sensors, generally requiring expensive instruments And a complex experimental architecture for wavelength drift measurements. & The problem of detecting equipment is also very difficult for the measurement of dynamic physical quantities. 3 201041327 SUMMARY OF THE INVENTION It is known from the above S that the optical fiber sensor that monitors the change of the relevant physical quantity by measuring the wavelength drift method needs to use the expensive instrument and the complicated experimental architecture to measure the wavelength drift, and for the dynamic The measurement of physical quantities is also very difficult. In view of the above, the main object of the present invention is to provide a whispering gallery mode demodulation fiber grating sensing system, which is a fiber optic sensing system with low cost and dynamic measurement compared with the prior art. The technical means for achieving the above purpose is to enable the modal modal demodulation fiber grating sensing system to include: - the sensing element is used to contact a to-be-tested end to sense a physical change generated by the end to be tested; a fiber optic coupler is coupled to the sensing element; and a reflective flb $ monitoring system is coupled to the fiber optic shank and includes a fiber optic ring as a demodulating element 'the reflected energy monitoring system outputs light and 0 is coupled via the fiber The device is transmitted to the sensing element and receives light reflected from the sensing element back to the fiber coupler, and the reflected light is caused by the fiber optic ring to generate a Whispering Gallery Mode interference for demodulation, thereby detecting the reflected light. The amount of change in energy corresponds to the amount of physical change of the end to be measured. The optical fiber sensor of the invention mainly utilizes measuring the reflected light energy instead of measuring the wavelength drift, which can effectively reduce the equipment cost and simplify the experimental structure; and at the same time construct a measuring system suitable for static and dynamic pressure, because of low cost and small volume Other advantages will be widely used in aerospace, civil engineering, automotive transportation, precision machinery and other industrial fields. 4 201041327 [Embodiment] Please refer to the first figure, which is a schematic diagram of a preferred embodiment of a modal demodulation fiber grating sensing system of the present invention, comprising: a sensing component (1 〇) In contact with a terminal to be measured, the physical changes generated by the terminal to be tested, such as temperature, strain, and pressure, may be measured, which may be a fiber Bragg grating (FBG) sensor; a fiber coupler (20), connected The sensing element (1〇); a reflective energy monitoring system (30) connected to the fiber coupler (2〇) and having a fiber ring (31) as a demodulating element. In this embodiment, the reflecting month bi The monitoring system (30) outputs light and is transmitted to the sensing element (10) via the fiber combiner (2), and receives light reflected from the sensing element (1〇) back to the fiber coupler (20) The fiber optic ring (31) causes the reflected light to generate destructive interference in the Whispering Gallery Mode for demodulation, and then detects the amount of change in the reflected light energy to measure the physical variation of the end to be tested. The aforementioned demodulation method is based on the Whispering gaMery (WG) interference mode generated by the curved optical fiber. When the light is transmitted through the optical fiber, part of the light is transmitted from the core to the shell. After being reflected by the fiber and the air interface, it is again combined with the fiber in the fiber to generate an interference spectrum with the light originally transmitted into the core. In this embodiment, the reflected energy monitoring system (3A) further includes a light source generating device (32) and a light receiver (33). The light source generating device (32) is connected to the light-coupler (2〇) to output light to the fiber consumable (2〇); the light receiving 11 (33) can be - photoelectric: a polar body, Connecting the fiber ring (31) 5 201041327 ' to receive the light reflected from the sensing element (10) back to the fiber coupler (20), and convert the light energy into an electrical signal, according to which the voltage signal can be analyzed The amount of physical change at the end. According to the second figure, the sensing system must be adjusted before operation to adjust the characteristics of the wave to be measured, that is, to determine the range of light energy (Dynam丨c Range). The two ends of the fiber ring (31) used as the demodulating element are horizontally fixed on the two translation stages (4〇), and the two ends of the fiber ring (31) are respectively connected to a light source generating device (5〇) and a spectrum. The analyzer _, the light source generating device (4 〇) output light, transmitted to the spectrum analyzer spectrum analyzer (10) via the fiber ring (31) to display a spectrogram of the light energy variation curve. As the light passes through the fiber optic ring (31), due to the modal interference of the whistle gallery, the optical energy loss of part of the wavelength exhibits an attenuation band _e_ti〇n Band) on the spectrogram, by adjusting the two translation stages. The distance between _ changes the radius of the money ring (31), which in turn changes the light interference, which allows the spectrum analyzer (7〇) to display different shoots, occupants, * outside & θ Ο 农 农 减 减The frequency spectrum of the curve of variation, as shown in Annex 1, for the change of light energy and wavelength, 2 different + diameter, the band of the agricultural subtraction band has a small slope and a wide range, and the measurable wavelength variation range is large; Slope,,,Μ „ The wide-ranging band of the drought is small, but the measurable wavelength change is small but sensitive. It can be seen that changing the diameter of the fiber ring (31) can change the system's desired machine. The dynamic range of the measured light energy of ', ^, and ®' is compared with the measurement method of the filter characteristic of the general filter. L-round, the system provides more flexibility when determining the dynamic range of the optical fiber ring (31) The adjustment, if attached, is to complete the light energy to be measured. ~ shown in this dynamic range sensing 6 201041327 component (10) is subject to the wavelength shift of the light transmission caused by the increase of strain energy, which will be able to reflect the change of light energy 又. And because the light energy can pass through the aforementioned light receiver ( 33) Turning to electricity m, therefore, by measuring the stress variation of the sensing element (1〇) by measuring the magnitude of the (four) value, the strain & normal operation as shown in Annex III can be obtained. The reference value of the time stress change. In addition to measuring the strain, the corresponding value of the temperature and the like can also be obtained in this way. In the actual operation, the sensing element (1 〇) can be brought into contact with a terminal to be tested: For example, when the sensing element (buried in the bridge or the building structure is received by the reflected energy monitoring system (33) through the transmission and reflection of light, the voltage (ie, the monitoring light energy) Variation), when the bridge structure produces a stress change, the degree of strain can be known from the voltage change. In summary, the present invention mainly uses the measured reflected light energy instead of measuring the wavelength drift to pass the phase-energy monitoring. Indirect derivation of the physical s size to be measured will effectively reduce equipment costs and simplify the experimental architecture, while constructing a measurement system suitable for static and dynamic pressure, and its advantages such as low cost and small size will be widely used. Aerospace Science, Civil Engineering, Automotive Transportation, Precision Machinery, etc. [Schematic Description] First: A schematic diagram of a preferred embodiment of the present invention. First Figure: A preferred embodiment of the present invention Schematic diagram of calibration: Annex I: Spectrogram of different energy variation curves of the present invention. Annex 2: Schrogram of the Bragg grating strain spectrum demodulated by the fiber optic ring of the present invention. ~ 7 201041327 . Annex III: Light of the present invention Strain correction diagram of the receiver. [Main component symbol description] (10) Sensing element (20) Fiber coupler (30) Reflected energy monitoring system (31) Fiber ring (32) Light source generating device (33) Optical receiver ( 40) Translation stage (50) light source generating device (60) spectrum analyzer 〇
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