A simple measurement technique is proposed for multi-pitched grating inserted in an external cavity diode laser. Measuring grating rotation and variation of multiple resonant wavelengths enables us to estimate grating periods and Littrow angles simultaneously. We experimentally determined that sufficient variation of resonant wavelength (i.e. ∼1.6nm) could be obtained even with a grating rotation less than 0.05. The grating periods and Littrow angles of two dual-period holographic gratings were successfully measured with less than 1% error. This technique can be applied to the motionless measurement of multi-pitched gratings, diffractive optics, and metasurfaces in the future.

针对插入外腔二极管激光器中的多节距光栅提出了一种简单的测量技术。测量光栅旋转和多个谐振波长的变化使我们能够同时估计光栅周期和利特罗角。我们通过实验确定，即使光栅旋转小于 0.05，也可以获得足够的谐振波长变化（即~1.6nm）。成功测量了两个双周期全息光栅的光栅周期和利特罗角，误差小于 1%。该技术将来可以应用于多节距光栅、衍射光学和超表面的静止测量。