The light conductor, or Lichtleiter, consists of two parts: (a) the light container with the optical device and (b) the mechanical part with the viewing tubes which are fitted to accommodate the anatomical access of the organs to be examined. The instrument is about 35 cm high, shaped like a vase and made out of hollow lead, covered with leather. A round opening on its front side is vertically divided in two parts. In one half, a wax candle is placed and held by an arrangement of springs so that the flame is always in the same position. Concave mirrors are placed behind the candle and reflect the light of the candle through the one half of the tube to the eye of the observer. A concave lens is placed on the side towards the “Lichtleiter”.
According to the width of the cavities to be examined, i.e. the ear, the urethra, the female urinary bladder, gunshot tracts, etc. different specula were used. These specula consist of blade-shaped prongs which could be spread open by using a screw device in order to expand the channels.
In this Frankfurt model light conductor by Philipp Bozzini, the two tubes for light and image transport lie side-by-side. This explains why the opening for the ocular is located off-centre (more to one side) on the back wall of the light receptacle; this is typical of the Frankfurt light conductor.
Light and image transport are separated in the light receptacle by inserting the so-called reflection tube. The reflection tube ensures that the light emitted by the light source does not interfere with image transport; in addition, the reflection tube divides the opening on the front wall, to which the various examination shafts are attached, for light transport and image transport.
Complete separation of the channels for light and image transport was necessary in Bozzini’s light conductor only when the “tube for angular light transport” (a laryngoscope shaft) was used; this was a shaft in which the direction of light or image transport at the shaft tip was deflected 90° by means of a mirror.