Prism-free differential interference contrast microscope with tunable beam shear distance

A beam shear distance module for generating first and second output light rays from a first input light ray, the first and second output light rays being separated by a beam-shear distance that is controllable, the beam shear distance module comprising:

• a beamsplitter (BS) configured to split the first input light ray into first and second split light rays respectively propagated on first and second light paths, the first and second light paths defining a reference vertical direction perpendicular to the first and second light paths;
• and
• first and second mirrors respectively located at distal ends of the first and second light paths, the first and second mirrors being oriented to cause each of the first and second split light rays to undergo a two-stage reflection such that the first split light ray yields a first reflected light ray directed to the BS and propagated along a first direction parallel to the second light path and such that the second split light ray yields a second reflected light ray directed to the BS and propagated along a second direction parallel to the first light path, the first and second reflected light rays being processed by the BS to yield the first and second output light rays propagated along the first direction, wherein orientations of the first mirror and of the second mirror in yaw angle, pitch angle, or both, with respect to the reference vertical direction are jointly adjustable to control the beam-shear distance between the first and second output light rays such that the beam-shear distance is realizable, controllable and tunable without a need for using any birefringent crystal-based prism in the beam shear distance module.