Abstract
For the evaluation method of micro gear accuracy, the most suitable approach should be to use a pair of rotary encoders. The difficulty is that the diameter of the rotary encoder should be at least smaller than the reference diameter of a test gear in order to avoid the interference between the encoder and the mechanical coupling of the other encoder. Our target micro gears are supposed to have the reference diameter smaller than 1 mm. The authors here try to manufacture the grating disk whose diameter is smaller than 1 mm in order to achieve both the small width of the gratings and homogeneity of it by utilizing the combination of electron beam (EB) lithography and etching technique of silicon substrate. The optimum conditions were investigated to get adequate radial grating grooves with dummy sample patterns. Finally, a grating disk which has 1,000 gratings in the size of 1mm in diameter is successfully manufactured.
