Two-dimensional imaging under meridional propagation through a dispersive thick lens based on RGB distributions and defocused planes

In this paper, we consider a 2D polychromatic transparency serving as an object in front of a dispersive thick lens. The RGB based constituent colors are treated in terms of a center wavelength with a spectral spread, thereby enabling the phasor interpretation and tracking along axial image planes. It turns out that any individual color of the input transparency has a unique focal length or image position in the (meridional) observation plane after propagation through the lens. Under dispersion, image characteristics such as foci, axial location, magnification, and amplitude are controlled by narrow sidebands around a monochromatic carrier. The analytical results (derived numerically) are compared with standard non-dispersive imaging. Particular attention is given to the nature of transverse paraxial images in fixed axial planes, whereby defocusing effects due to dispersion are demonstrated in the manner of spherical aberration. Such selective axial focusing of individual wavelengths may find applications in improving the conversion efficiency of solar cells and photodetectors exposed to white light illumination. (c) 2023 Optica Publishing Group