methods , apparatus and devices for providing images based on the optical phase gradients within a biological sample can be provided . in one exemplary embodiment , a tethered and / or untethered capsule can be introduced into a biological specimen to acquire images by illuminating the specimen from at least two different angles , while an objective lens arrangement can relay an image from the illuminated sample to an imaging sensor array . the difference between images acquired using differing illumination angles and from the same position in the sample can indicate a phase contrast in a certain technique . the image focal plane provided by this exemplary arrangement / device , e . g ., being planar by definition , constitutes only a small fraction of a volumetric specimen . to provide , e . g ., three - dimensional or volumetric imaging , according to one exemplary embodiment of the present disclosure , it is possible to utilize a translational and rotational drive mechanism by which the thin plane of imaging is swept through the sample such that a large volume is imaged over time . to improve the coverage of the image plane sweep , according to yet another exemplary embodiment of present disclosure , it is possible to utilize a tilted camera and / or a non - paraxial optical lens arrangement , such that the image focal plane is not perpendicular to the optical axis of the objective lens arrangement .