A method for investigating off-axis Gaussian beams

In order to achieve a way to propagate a Gaussian beam through a set of optical elements, several aspects of optics need to be combined. We will show that by using Gaussian optics in combination with ray tracing, we can find a method to include several complexities that are not possible with the common rules of Gaussian optics. We will check our theory with experiments where we shoot Gaussian beam at an offset with respect to the optical axis of the lens-system. For small deviations of 1.0 cm from the optical axis on a 2.54 cm wide lens, the theory is in good agreement with the measurements.