Refraction techniques for continuous laser beam deflection: An overview

This paper presents an overview of techniques based on refraction for light laser beam deflectors, including laser scanners. A new typology is proposed based on the principle of operation, and the reader is directed to the literature related to the individual subtypes and to some arbitrarily selected representative examples. This review is limited to the continuous or quasi-continuous mode of operation. Two types of basic steering deflection techniques can be distinguished, which involve a variable angle of incidence at the refractor, and a variable refractive index. Techniques with a variable angle of incidence at the refractor can be divided into the following main subgroups: rotary wedge, Risley prism, double lens adjustable optical wedge, liquid wedges, decentered refractors, and variable curvature of the refractive interface. Two main subgroups of techniques based on variable refractive index are highlighted: those in which the refractive indices of the media that create the refracting boundary are changed, and those that use a variable gradient index for a medium. The main technical parameters (such as resolution, deflection angle, speed etc.) and useable properties are specified for each technique.