Study on the fabrication of blazed grating with sub-micrometer space on aluminum film

The saw tooth grooves of blazed grating ruled by ruling engine are formed by diamond tool which presses on the aluminum film evaporated on the substrate of optical glass or metal. The real shape of ruled saw tooth groove is different from that of the ideal groove and the ruling process indicates that there are the zero order planes, similar to the flat tops, on the grating grooves. The results of Fourier analysis for the real ruled grating featuring the zero order plane structure shows that the flat top width is an important factor for grating efficiency. Additionally, bigger pressure value loaded on the diamond tool and bigger lateral pressure value on the aluminum film will be benefit to the improvement of grating diffraction efficiency. Based on the grating interferometer, the high precision positioning control system of ruling engine guarantees the accuracy of the grooves space. High density blazed grating whose space is 0.83 mu m is manufactured and its' grooves spaces are very equidistant and uniform under the view field of AFM. And the infrared blazed grating, whose diffraction efficiency in the first order is up to 97 percent, is ruled successfully also.