Filter is used to transmit spectrum of definitive broad band in the continuous spectrum or to extract certain radiation in the line-spectra.
光学滤光片在连续的光谱中用于透过一定宽度的光谱带或在线状光谱中提取某些辐射。
2
Ship radiated noises include a lot of line-spectra which are valuable for targets identification. Therefore it becomes an important approach in the studies of underwater acoustics.