One or more devices, systems, methods and storage mediums for performing continuously, full range optical coherence tomography (OCT) without losing A-lines are provided. Examples of such applications include imaging, evaluating and diagnosing biological objects, such as, but not limited to, for cardio and/or ophthalmic applications, and being obtained via one or more optical instruments, such as, but not limited to, optical probes (e.g., common path probes), catheters, endoscopes, phase shift units (e.g., galvanometer scanner) and bench top systems. Preferably, the OCT devices, systems methods and storage mediums include or involve a phase shift device including at least a galvanometer scanner. The galvanometer scanner is preferably applied with or to a voltage with a triangle shape, the voltage having continuity or absolute constant frequency to obtain continuous images without losing any A-lines. The method(s) may include background subtraction, image shifting to compensate phase shifts and a DC noise reduction algorism.