  We present a high-resolution, simple and versatile system for imaging
ultracold Rydberg atoms in optical lattices. The imaging objective is a single
aspheric lens (with a working distance of 20.6 mm and a numerical aperture (NA)
of 0.51) placed inside the vacuum chamber. Adopting a large-working-distance
lens leaves room for electrodes and electrostatic shields to control electric
fields around Rydberg atoms. With this setup, we achieve an Rayleigh resolution
of 1.10 $\mu$m or $1.41\lambda$ ($\lambda=780$ nm), limited by the NA of the
aspheric lens. For systems of highly excited Rydberg states with blockade radii
greater than a few $\mu$m, the resolution achieved is sufficient for studying
many physical processes of interest.
