According to some embodiments a housing for the OCT comprises: (a) a tubular body with an inner diameter of less than 5 mm (for example less than 2 mm, and in some embodiments not greater than 1.5 mm), a first end, a second end and a window formed in the tubular body closer to the second end than to the first end, displaced from the second end, and framed by a portion of the tubular body, wherein the window has a width w. According to some embodiments, 0.05 mm