Imaging sensors to detect the four Stokes parameters, which have high sensitivity and high frame rates and are light weight and portable, have not been developed. In this paper, we report on our development of novel microscale achromatic retarders. A two-dimensional array of these retarders can be combined with an array of linear polarizers in an imaging sensor. This sensor will be able to capture images of the four Stokes parameters over a wide wavelength band. The achromatic retarder is a combination of two single-order waveplates. Each single-order waveplate is a surface-relief grating which was modeled using Rigorous Coupled Wave Theory. The images of an idealized terrestrial scene were generated by polarimetric ray tracing. We then simulate the image of circular polarization which would appear at the output of a realistic sensor. We conclude that the wide-band sensor is able to image Stokes parameter V when the degree of circular polarization in the scene is approximately 2% or greater.