Suitable off-axis space-based telescope designs

We describe here several off-axis designs for space-based telescope optimized for low scattered light and low emissivity. We show how the geometric optical performance can equal that of an on-axis conventional telescope while the diffractive performance fundamentally surpasses conventional telescopes because of the absence of pupil obstruction. The off-axis concept also allows wide-field and versatile instrumentation configurations enabling a variety of observations - such as high photometric dynamic range objects - that are not possible with more conventional designs, even with much larger apertures.