Various embodiments of the present invention comprise endoscopes for viewing inside a cavity of a body such as a vessel like a vein or artery. These endoscopes may include at least one solid state emitter such aas a light emitting diode (LED) that is inserted into the body cavity to provide illumination therein. Certain embodiments of the invention comprise disposable endoscopes that can be fabricated relatively inexpensively such that discarding these endoscopses after a single use is cost-effective. The endoscope may comprise a lens holder on a distal end of the endoscope for collection of light reflected from surfaces within the body in which the endoscope is inserted. This lens holder may have an inner cavity through which light passes along an optical path. Reflective surfaces on sidewalls of the inner cavity may direct light along this optical path. The endoscope further comprises an elongated support structure for supporting a plurality of rod lenses disposed along the optical path, said support structure having slots at predetermined distances through which said rod lenses respectively fit. This optical path may lead to a detector onto which images are formed.
