object lens focal length

基本解释

If the objective lens is closer to the compact disk than the focal length of the object lens then the cylindrical lens creates an elliptical image on the photodetector array.
如果物鏡與光磐之間的距離短於物鏡的焦距，柱麪透鏡就會使在光電探測器陣列上的成像變成橢圓影像。
Once you choose a lens whose focal length is closest to the focal length required by your imaging system, you need to adjust the working distance to get object under inspection in focus.
一旦你選擇一個鏡頭其焦距是最接近於你成像系統所需之焦距，你需要調較工作距離去獲取觀察目標物的焦點。
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