Ключевые слова: axis, beam, biconcave, biconvex, concave, convergence, convergent, converging, convex, curvature, distance, divergence, divergent, diverging, focal, focusing, formation, glass, image, length, lens, light, magnification, magnifying, meniscus, negative, object, optics, physics, plane, point, positive, radius, real, spherical, spread, virtual,