A method of fabricating an addressable array of biopolymer probes on a substrate according to a target array pattern using a deposition apparatus, and a deposition apparatus which can execute the method and computer program products for the apparatus. The deposition apparatus which, when operated according to a target drive pattern based on nominal operating parameters of the apparatus, provides the probes on the substrate in the target array pattern. The method includes examining at least one operating parameter for an error from a nominal value which error will result in use of the target drive pattern producing a discrepancy between the target array pattern and an actual array pattern deposited. When an error is detected deriving, based on the error, a corrected drive pattern different from the target drive pattern such that use of the corrected drive pattern results in a reduced discrepancy between the target and actual array patterns.