High-resolution, large-angle optical beam scanning methods are sought to meet the ever-increasing demands of free-space laser communication, medical imaging and treatment, printers, scanners, and laser radar. We present a precise steering method with high angular resolution and a wide scanning range. The proposed beam-steering device is also lightweight and compact, which are significant advantages in many applications. The scanning is implemented by means of a pair of diffraction gratings, which can be translated relative to one another, and a tunable-wavelength laser. Thus the beam is steered by the combined effect of two independent mechanisms. The agility of wavelength tuning enhances the performance of a grating-based device, while the sensitivity to chromatic aberrations is minimized by performing the coarse steering with the diffraction grating. The system performance is demonstrated experimentally, and the results are reported. To the best knowledge of the authors, We present for the first time a scanning system that includes a combination of a pair of diffraction gratings and a tunable-wavelength laser.