Made by mechanically carving a thin metal surface with a diamond knife. This type of grating generally does not have a high number of lines, ranging from 20g/mm to 1800g/mm, and has a wide spectral range. When the spectral range exceeds 1500nm, the grating can only be used. Due to the manufacturing process of the engraved grating, the cost of producing an original engraved grating (master grating) is relatively high, resulting in the generation of a replicated grating. The replicated grating is copied from the master grating, and its performance may be slightly inferior to that of the original engraved grating. There are mainly several types of groove shapes

The advantage of grating is its high diffraction efficiency, especially at the wavelength of its shining angle, where the diffraction efficiency can even reach 80% -90%. The disadvantage is the presence of ghost lines and high stray light, which is mainly caused by periodic errors or errors in grating production during engraving.