Primary researches on the groove density variations of bending grating were experimented. Firstly

highly varied line-spacing gratings (nearly 9.2 line/mm) were fabricated. Meanwhile thin glasses with the thickness 0.16 mm were chosen as their substrates. Consequently

the long trace profiler was used to test the curved substrates precisely and the groove density of the gratings were measured by diffractive method. Experimental result shows that the error is 0.41 line/mm rms between experimental and theoretical values.