Light Guides & Adapters

The light that is emitted from either of the light sources, needs to be carried to the light post of the scope so that it can be passed inside the body to illuminate it. This carriage of light form the source to scope has to be with minimum loss of light energy so as to maximise the useful life of the bulb. Loss of light can occur on two fronts; due to loss in open environment and due to loss of energy on account of reflections inside the carrying medium. To prevent loss in open environment at the connector, lenses are built-in inside the control unit to focus all the light at the required exit point, the point that connects with the light guide. To prevent both the kinds of losses, modern light sources come with light guides that are specifically designed to transmit maximum and lose minimum light. This purpose of maximum transmission is achieved using either the liquid light cable or the fibre optic cable. The liquid light cable is single tube filled with liquid that allows maximum transmission of light. This type of light guide is best as it gives the brightest light. On the other hand, fibre optic cable is made up of thousands of fibre optic strands. Fibre optic strands use the principle of total internal reflection that make them ideal for minimum loss and maximum transmission uses. The number of strands within one cable vary with the diameter of cable. Thicker the cable, more the number of strands and brighter is the light. Although fibre optic technology gives maximum transmission, it still isn’t as efficient as liquid light cables. Due to this, the light is not as bright as its liquid counterpart. Also, liquid light cables are more resilient against bending as compared to fibre optic cables whose strands are very fragile and may break due to acute bending. But, liquid light cables are much more expensive than fibre optic cables. Thus, most of the manufacturers supply fibre optic cables by default, unless otherwise stated.

To attach these fibre optic/liquid light cables to the light source and the scope, adapters are provided. These adapters are different for different light sources and scopes. Each scope and light source has its own distinctive attachment mechanism. For the light source to be universal, different connectors are made available by all the companies dealing in light sources. Even the receptacles on the control panel of light source are made so that they can be selected for particular make of cable and scope.