A prediction apparatus is in communication with an optical source configured to produce a pulsed light beam for use by a photolithography exposure apparatus. The prediction apparatus includes: a photolithography module in communication with the photolithography exposure apparatus and configured to receive an identifier, the received identifier lacking data relating to an actual firing pattern defining properties of the pulsed light beam; and an optical source module in communication with the optical source, the optical source module configured to provide a forecast firing pattern to the optical source. The forecast firing pattern is associated with and determined from the received identifier, and forecasts one or more properties of the actual firing pattern.