This paper presents an approach that is capable of producing a color image using a single composite diffractive optical element (CDOE). In this approach, the imaging function of a DOE and the spectral deflection characteristics of a grating were combined together to obtain a color image at a certain position. The DOE was designed specially to image the red, green, and blue lights at the same distance along an optical axis, and the grating was designed to overlay the images to an off-axis position. We report the details of the design process of the DOE and the grating, and the relationship between the various parameters of the CDOE. Following the design and numerical simulations, a CDOE was fabricated, and imaging experiments were carried out. Both the numerical simulations and the experimental verifications demonstrated a successful operation of this new approach. As a platform based on coaxial illumination and off-axis imaging, this system is featured with simple structures and no cross-talk of the light fields, which has huge potentials in applications such as holographic imaging.

The diffractive optical element (DOE) can modulate the light to image in a fixed distance. However, when the wavelength of the light is single and fixed, the imaging is single. In this paper, we proposed a novel architecture to solve this problem. The birefringent material is used as the substrate of the DOE, and the polarization modulation is added in the design of the DOE. The two orthogonally linear polarized lights with the same wavelength modulated by the DOE image differently at the same distance. The imaging of incident light with different polarization is simulated, and the diffraction efficiency and the uniformity are also calculated to demonstrate the validity of this mew method.