Synthetic aperture lidar (SAL) can obtain high-resolution and high-data-rate images for remote target with small optical aperture under large forward squint angle condition. Thus, SAL can be an important mode of optic imaging detection. In this study, the working mode, system scheme, performance parameters, and key technologies of SAL with 100 mm diameter, 20 km detection range, and 0.05 m resolution are analyzed. A concept of a diffractive optical system conforming to the dome is proposed to reduce the aerodynamic influence and volume and weight of the equipment. The laser beam broadening and one-dimensional beam scanning method based on frequency scanning change is studied, and the beam pattern simulation results are presented by using the model of microwave phased array antenna. The results show that the SAL imaging detection technology based on curved-conformal diffractive optical system is feasible.