The invention provides a rigid endoscope utilizing a high refractive index (HRI) tunnel rod, preferably made of glass, for transfer of image light from a distal end to a proximal end of the device, such HRI tunnel rod being modified so that a minimum of light is scattered and reflected within the rod, thus minimizing veiling glare and contrast reduction of the image which is formed near the HRI tunnel rod's proximal end. The HRI tunnel rod shortens the apparent distance from the proximal to the distal end by virtue of its refractive index being greater than that of air, and also provides a light tunnel which can carry the image over a relatively long distance by virtue of its modified inside walls. A preferred method of modification includes hydrogen firing of the HRI tunnel rod in order to create a thoroughly blackened inner surface which is highly non-reflective, even at grazing incidences. Relatively simple lenses are incorporated at the ends of the rod for image formation so as to cover a wide object field and to relay the image to a video camera. Stereo measuring embodiments of the endoscope provides dual optical paths for yielding two images containing parallax data.