Photocells are also used in photometry and spectroscopy.
光电管也应用于光度学和光谱学。
2
With ordinary photocells, one can pick up the frequency between two different lasers.
用普通光电池，人们就能够探测到两个不同的激光之间的拍频。
3
A wise choice might be to choose from among inexpensive outdoor security light fixtures now available that combine both photocells and motion detectors.