雙軸式光學雷射振動儀之研製

DEVELOPMENT OF A BIAXIAL OPTICAL LASER VIBROMETER

童景賢(Jingsyan Torng) ； 黃元瑞(Yuan-Ruey Huang) ； 彭偉彰(Wei-Chang Peng) ； 張哲魁(Che-Kuei Chang)

《南亞學報》 37期 (2017/12) Pp. 373-386

摘要

DVD 雷射頭是DVD 光碟機中的重要元件，由於系統穩定價格便宜，因此利用DVD 雷射頭來發展一套精密的振動量測系統是可行的。DVD雷射頭是由雷射二極體(LD)、分光鏡、物鏡、光檢測元件、繞射光柵與圓柱透鏡等六個元件所組成的。具有體積小、重量輕、消耗的功率小、單一的輸出光譜等特點，非常符合發展測量振動的需求。DVD雷射頭內部有一個四象限感測器(Quadrant photo-detector)，主要是接受待測物上反射鏡之反射光的受光強度，藉以量測個別不同受光的訊號ABCD，而將四個訊號相加減，(A+C)-(B+D)，可形成S-curve 線性，以其直線部分(約7μm)之中點作為參考點，來判斷微小振動量的大小。因振動產生的方向不可能是單一向，所以本研究設計可量測雙軸(X軸及Y軸)的振動量的振動儀，以接收振動的訊號。機構部分是以兩片呈九十度角之彈簧鋼片相連接，以量測上下(Y軸)與左右(X軸)兩方向之振動量，片狀彈簧可使振動方向朝向X與Y軸運動，並且避免產生旋轉之現象。實驗結果顯示，本研究之雙軸式光學雷射振動儀可量測的最大振幅為15μm，頻率最高為2Hz。

關鍵字

DVD雷射讀取頭 ； 振動儀 ； 四象限感測器 ； S曲線

並列摘要

Laser pickup head is a key component in DVD players. With six components, a laser head includes laser diode(LD), objective lens, collimator, quadrant photodiode, diffraction grating and cylindrical lens. For being stable and inexpensive, using laser pickup head to develop a vibration measurement system is feasible. The structure of the laser head has a quadrant photo-detector, which receives the light intensity from the reflected mirror on the measured object. The formation of the S-curve is from the signal ABCD of quadrant photo-detector by (A + C) - (B + D). The linear part of S-curve is about 7μm. The midpoint of S-curve is regarded as a reference point to determine the range of vibration amplitude. Because the direction of vibration is not able to be in one direction, this study designed to measure the vibration in biaxial direction (X-axis and Y-axis). The mechanical part is jointed with two pieces of spring steel plates at a 90 degree angle to measure the vibration in two directions of up and down (Y axis) and left and right (X axis). The leaf spring can make the vibration direction toward X and Y axis and prevent the phenomenon of rotation. After experiments, the results showed that the biaxial optical laser vibrometer is able to measure the maximum amplitude of 15μm and the maximum frequency of 2Hz.

並列關鍵字

DVD optical pickup-head ； Vibrometer ； Quadrant photo-detector ； S-curve