empty spot 中文意思是什麼

According to the guidline, two nd : yag lasers have been designed and set up, one is end - pumped by lower output power ld using a selfoc micro lens, and the other is end - pumped by high output power ld using a pair of lenses are designed, and the characteristics such as output power and power stabilization of both solid - state lasers are investigated. thirdly, when an empty liquid crystal cell is inserted in the cavity of the nd : yag laser pumped by high power ld, the laser can operates in single axial mode. finally, according to the relationship between the laser output power and the longnitudinal a ld - end - pumped nd : yag laser sensor for displacement measurement has been investigated theoretically and demonstrated experimently, the results indicate that when the mean radius of pumping inside the laser cavity is far less than that of the oscilating laser mode, the exponential of the output power is a gauss function of the longitudinal positon of focused spot of ld pumping beam, both the measurement range and the sensitivity are dependent on the incident pumping power, as the incident pumping power is increased, the measurement range is enlarged and the sensitivity is improve d

本文首先介紹了ld泵浦nd ： yag激光器的發展狀況、主要特性及其應用，從四能級速率方程出發，推導了ld泵浦nd ： yag激光器的閾值、輸出功率和斜效率的表達式，並簡述了激光器的工作原理、結構型式和倍頻方法；其次，以空間相關的速率方程為基礎，提出了ld端面泵浦nd ： yag激光器的設計方法，給出了一定泵浦耦合方式下，振蕩光模尺寸、最佳輸出耦合率、泵浦光模尺寸、泵浦光焦斑位置等參數的選取依據，以此為依據，設計了自聚焦透鏡耦合小功率ld泵浦nd ： yag激光器和透鏡組耦合高功率ld泵浦nd ： yag激光器，對激光器的輸出功率和功率穩定性等特性進行了實驗研究；再次，在帶尾纖輸出的高功率ld泵浦nd ： yag激光腔內插入一隻空液晶盒，觀察到了激光器以單縱模運轉；最後，根據泵浦光焦斑端面位置對激光輸出功率的影響規律，提出了ld端面泵浦nd ： yag激光位移傳感新方法，並進行了理論和實驗研究，研究結果表明：當激光晶體內泵浦光平均光斑半徑遠小於振西安理工大學碩士學位論文蕩光束腰半徑時，激光輸出功率的自然指數與泵浦光焦斑的縱向位置成高斯變化規律，測量范圍和靈敏度依賴于泵浦功率，隨著泵浦功率的增加，測量范圍擴大，靈敏度提高，當端面泵浦功率為7 . 24w （最大輸出功率為1 . 926w ）時，激光位移傳感器的測量范圍和靈敏度分別是13 . 045mm和0 . 148mw / pm 。

The evening of the same day saw the empty wagon reach again the spot of the accident.

當天傍晚，那輛空車又回到了出事的地點。

In that spot the night was not always empty, the darkness not always silent.

在那個地點，夜色里並不老是空無一人，黑暗裡也並不老是鴉雀無聲。

We built a test road and after one year, we used surface wave exploration to test. the result is that the repaired layer felt old road well and have no empty spot. we used the pendulum friction tested and the results are the wear - resisting property is better than cement concrete pavement and pendulum friction is higher than cement concrete pavement

此種材料同原有水泥混凝土路面的粘結性能強，強度上升快，韌性大，抗凍性好，防水抗滲；通過試驗路運營一年多的檢測結果表明：通過面波儀測定修補層與原路面粘結良好，沒有脫空點；利用擺式摩擦儀測定其耐摩耗性能優于原水泥混凝土路面。

Time after time, my mind kept on going to that empty spot,

好多次，我的思緒都離不開她

Time after time, my mind kept on going to that empty spot

好多次，我的思緒都離不開她