A novel, graphical method to analyze optical scanners with Risley prisms

The graphical method we develop is presented for scanners with two rotational Risley prisms, in an analysis that considers all system parameters: angles, refractive indexes, and apertures of the prisms, rotational speeds, distance between prisms, as well as from the scanner to the target plane. Marshall’s parameters are also used: k, ratio of the angles of the prisms; M, ratio of the rotational speeds. The scan patterns of the different systems are simulated using a mechanical design program, CATIA V5R20 and basic prisms equations. The advantages of the method are: exact scan patterns are obtained, in contrast with approximative methods (e.g., using the paraxial approximation); the method is simple, fast, and easy-to-use, in contrast to (rather complicated) analytic approaches. Rules-of-thumb to design such scanners are extracted from the analysis. Experimental validation and a discussion on perspectives of Risley prisms conclude the study.