Structured mirror array for two-dimensional collimation of a chromium beam in atom lithography

Direct-write atom lithography, one of the potential nanofabrication techniques, is restricted by some difficulties in producing optical masks for the deposition of complex structures. In order to bring a further progress, a structured mirror array is developed to transversely collimate the chromium atomic beam in two dimensions. The best collimation is obtained when the laser red detunes by natural line-width of transition ⁷S₃ → ⁷P₄⁰ of chromium atom. The collimation ratio is 0.45 vertically (in x axis), and it is 0.55 horizontally (in y axis). The theoretical model is also simulated, and a success of our structured mirror array is achieved.