Altitude axis precision is important to performance of large aperture telescope. At practice
the tested result can not reach the system requirement
but the performance is well enough. The main reason is the deformation of centerpart. In this paper
1m telescope’s centerpart is analyzed by the FEM
and then finding the Altitude axis max deformation versus pitch angle curve is sinusoidal curve
that is the same as the tested results curve. We also calculate the influence of deformation on axis precision .We use the compensation method: add the tested results to calculated result. By this way
the PV error of axis shake is reduced from 2.42″ to 0.95″
the RMS error is reduced from 0.7″to 0.3″
the system precision model is improved.This can provide theory of even larger telescope’s design and test.