We report on the development and characterization of a field-portable hyperspectral imager designed to collect 128-band image cubes simultaneously in both the 4-5.25 \mu m (mid wave infrared, MWIR) and 8-10.5 \mu m (long wave infrared, LWIR) bands for detection of target as well as chemical/biological agents. The imager uses a specially designed diffractive optics Ge lens with a cooled dual-band 320..240 HgCdTe focal plane array. This lens performs both imaging and dispersive functions. The imager collects a single-color full scene image with a narrow band in the LWIR (e.g., at 8 ..m) using the first order diffraction and corresponding single-color image in the MWIR (4 ..m in this case) using the second order diffraction at the same time. Images at different wavelengths are obtained by moving the lens along its optical axis to focus the corresponding wavelengths. Here we will discuss the imager and present field test data and result