Combined retardation optical device

摘要

A combined retardation optical device includes a first retardation optical plate and a second retardation optical plate. The second retardation optical plate contains a flat portion and a multi-step portion. This multi-step portion has several step-like flat surfaces with predetermined heights. The flat portion contacts with the first retardation optical plate. Both the first retardation optical device and the second retardation optical plate are made from birefringent materials. This invention is easy to switch to a different retardation condition for observation. Plus, there is no need to adjust or replace any element.