Dual mirror optimized scanning for telecentric lens

Galvanometers are commonly used in terahertz imaging systems due to their increased scanning speed in two dimensions. Typically, a telecentric f-theta lens is employed to ensure normal incidence on the target plane in reflective imaging systems. Galvanometric scanners, however, introduce beam aberrations in the target plane due to the use of a separate reflector for each scanning axis. In this work, we present a galvanometric scanner with a modified geometry, which reduces beam aberrations and increases telecentricity. Ray tracing and physical optics simulations show that by scanning the first reflector with respect to an offset point located at the center of the second reflector, the scanned beam behaves as if it is being scanned from a single point. By fixing this point in the focal point of the lens, we can minimize beam aberrations. Comparative analysis shows improved telecentricity (±1° at the scanning edge) and beam spot size, with acceptable f-theta distortion and negligible deviation from normal incidence.