He focuses the lens of a microscope. 他調整顯微鏡的透鏡以定焦點。
A lens is an optical system including two refracting surfaces. 一個透鏡是包含兩個折射面的光學系統。
Objectives which consist only of one lens can be used for visual and photographic observations. 由單透鏡組成的物鏡可作目視和照相觀測用。
Which shows that the hybrid refractive-diffractive lens can effectively eliminate the aberrance of a telephoto lens with lower weight and simple structure. 結果表明，利用折衍混合能有效地校正長焦物鏡的像差，極大地降低系統的重量和複雜程度，不失為長焦物鏡設計的一條有效途徑。
