An idea of Fresnel telescope full-aperture synthesized imaging ladar is proposed, which is based on the optoelectronic data collection from the relative scanning between target and two cocentric coaxial beams of polarization-orthogonal quadratic wavefronts, and the image reconstruction from the complex quadratic phase decoded with optics and digital processing. It has two operational modes with moving target by 1D beam scanning and statistic target by 2D scanning. The imaging resolution is higher than that from the diffraction limit and 3D imaging is also possible. Because of the transformation of spatial signal to temporary signal and the utilization of coherent detection of coaxial beams, both the imaging S/N ratio and the receiving sensitivity are improved, and particularly the atmospheric influence is decreased greatly, optical receiving system of low quality is allowed to use to increase optical receiving aperture and decrease laser transmitting power. The systematic optoelctronic and mechanical configuration is quite simple due to the use of an optical hybrid. The detailed description of principle and mathematical analysis is given.