Thick lenses systems

The matrix optics formalism is applied to show that a simple Gaussian equation enough relate object and image distances in an optical system consisting of arbitrary number thick lenses cascade immersed air. First, the case single lens was studied. Applying sequentially matrixes corresponding refraction displacement ray, imposing certain conditions on behavior bunch rays being refracted by lens, there were found characteristic parameters such as focal distance, back front points, principal planes. Then relating found, which, after coordinate transformation, becomes well-known equation, usually used describe more idealized thin lens. Further, extended compound systems two, three N cascade. It also sufficient no matter lenses. Key words: Matrix optics, lenses, length, planes, focus, multi-lenses system.