Patent ID: 8508589

Claim:
An imaging system for generating images of a sample, comprising: an illumination source for illuminating the sample; an image viewing subsystem for viewing the images formed from the sample; one or more tunable optical wave plates and one or more birefringent elements, which are positioned between the sample and the image viewing subsystem, so that the images from the sample pass through the tunable optical wave plates and the birefringent elements before reaching the image viewing subsystem, wherein the tunable optical wave plates comprise a first liquid crystal panel and a second liquid crystal panel, and the birefringent elements comprise a first birefringent element and a second birefringent element; one or more polarizers, a device that changes one or more phase retardation states of the tunable optical wave plates resulting in a change of one or more polarization states of the image; and a controller that modifies the device to change the phase retardation states of the tunable optical wave plates; wherein the first liquid crystal panel is disposed between the sample and the first birefringent element, the first birefringent element is disposed between the first liquid crystal panel and the second birefringent element, the second birefringent element is disposed between the first birefringent element and the second liquid crystal panel, and the second liquid crystal panel is disposed between the second birefringent element and the image viewing subsystem, and wherein the first liquid crystal panel, the second liquid crystal panel, the first birefringent element, the second birefringent element and the polarizers are disposed between the sample and the image viewing subsystem along an optical axis comprising the sample and the image viewing subsystem, so that a focal distance of a reflected image passing through the imaging system has one or more different values based on the phase retardation of the first liquid crystal panel, the second liquid crystal panel, and the polarization states of the polarizers.