For the first time , three types of sine structures for wavelength linear scale in grating spectrum instruments are described systematically . the tuning structures for wavelength linear scale in both littrow and littman set - up external - cavity laser diodes are designed ( 3 )首次系统地分析了光栅光谱仪器中的三类正弦机构,分别设计了可实现波长线性标度的littrow和littman外腔半导体激光器调谐机构。