Provided is an exposure apparatus including a variable focusing device. The variable focusing device may include a transparent membrane that may be deformed in the presence of an electric field. The deformation of the transparent membrane may allow the focus length of a radiation beam to be modified. In an embodiment, the variable focusing device may be modulated such that a radiation beam having a first focus length is provided for a first position on an exposure target and a radiation beam having a second focus length is provided for a second position on the exposure target. A method and computer-readable medium are also provided.