This paper presents a new linearized ray-trace technique for analysis of general optical beam trains, developed for integrated structures/optics/controls design of spaceborne optical instruments. Computer routines based on our approach are fast enough to be executed in-line as part of a spacecraft dynamic simulation or as part of a real-time controller. We recast the standard exact ray-trace problem into a coordinate-free matrix form. Perturbation analysis yields closed- form expressions for optical sensitivity matrices.