A wide field-of-view crossed Dragone optical system using the anamorphic
  aspherical surfaces
  A side-fed crossed Dragone telescope provides a wide field-of-view. This type
of a telescope is commonly employed in the measurement of cosmic microwave
background (CMB) polarization, which requires an image-space telecentric
telescope with a large focal plane over broadband coverage. We report the
design of the wide field-of-view crossed Dragone optical system using the
anamorphic aspherical surfaces with correction terms up to the 10th order. We
achieved the Strehl ratio larger than 0.95 over 32 by 18 square degrees at 150
GHz. This design is an image-space telecentric and fully diffraction-limited
system below 400 GHz. We discuss the optical performance in the uniformity of
the axially symmetric point spread function and telecentricity over the
field-of-view. We also address the analysis to evaluate the polarization
properties, including the instrumental polarization, extinction rate, and
polarization angle rotation. This work is a part of programs to design a
compact multi-color wide field-of-view telescope for LiteBIRD, which is a next
generation CMB polarization satellite.
