An Alignment Error Budget for the Generation X Telescope

This paper presents a telescope level error budget for the Generation X telescope. The budget will include terms for the intramodule alignment as well as the alignment of the mirror assembly to the focal plane. A simplified model of the point spread function from each mirror module is introduced including the effects of misalignment on the half power diameter (HPD) of the image of a point source. The HPD of the misaligned system is compared to the HPD of an ideal system to determine a figure of demerit quantifying the degradation of image quality due to imperfect alignment. The alignment tolerances are treated as parameters of a probability distribution and used as inputs to a Monte Carlo calculation of telescope performance and a distribution of HPDs is generated. From this distribution, the probability of exceeding a given degradation of the intrinsic performance is generated. These probabilities are then fit to alignment tolerances to identify influential parameters and an initial budget allocation.