RESUMEN
Double-wedge prism scanners are typically used for one-dimensional (1D) scanning in imaging systems. This type of scanner operates on the principle of two identical wedge prisms counter-rotating around the optical axis with identical angular velocity in order to move the image formed by the optical system in the plane of detector arrays. However, the relationship between the deviation and rotation angles is not linear. The proposed solution to this problem involves using a metal ring inscribed with line markers. The interval between each of the line markers is unequal, and each line marker corresponds with the unequal angular orientation of the wedge prisms. The line markers are detected by a laser readout head (LRH), which converts the line marker signals to electric clock pulses to correct for the nonlinear distortion of the double-wedge prism scanner. This study presents a miniaturized LRH, electric driver circuit, and photodetector amplifier for this purpose.
RESUMEN
In this paper, double-wedge prisms, also known as Risley prisms, and composed of two wedge prisms, are presented with assemblies in four configurations. In the double-wedge prism scanner, the center of the two wedge prisms is aligned with the optical axis; thus, the optical system and mechanical structure are simple. In contrast to conventional scanners, its assembly is compact, robust, and insensitive to vibrations and wobbles. However, the relationship between the deviated and rotated angles is not linear, and the trajectory of the scan pattern is nonrectilinear; therefore, double-wedge prisms have rarely been used in imaging systems as a one-dimensional scanner until now. This study presents the optical characteristics of double-wedge prisms and proposes methods to solve the problems mentioned above. The experimental results demonstrate that the double-wedge prisms can be used in an imaging system as a one-dimensional scanner.
RESUMEN
The conventional ray deviation formula and analytical inverse solution for Risley prisms are traditionally derived by the first-order paraxial method, which is simplified and does not provide sufficient accuracy. When a light ray enters the wedge prism, the component that is perpendicular to the base side is deviated by the wedge prism and the component parallel to the base side is uninfluenced. In this study, the problem is presented and analyzed from the scalar form of Snell's law, and 2D vector algebra is used to solve the problem. The rotation and refracting angles of a single wedge prism are obtained by analyzing the propagation through the prism of incident rays from different directions, and ray deviation formulas are derived. Four configurations are described with ray deviation formulas and analytical inverse solutions deduced from the corresponding formulas for a single wedge prism. In the final section, two examples are considered for the four configurations. The numeric results demonstrate the accuracy of the inverse solution provided by the proposed method.
