Monday, August 27, 2007

Borescope Illumination

If you use a borescope it is necessary to illuminate the object you are observing. There are two basic types of borescope illumination: hot light and cold light. Hot light means the borescope contains a bulb at the tip. This is no longer common but some scopes still use this type of illumination. It has the downside of heating the object as well as the potential to break the bulb. Cold light means that there is an external light source and the illumination is transmitted through the scope using optical fiber. 
Light sources vary from portable flash light types, which attach directly to the borescope, to metal halide arc lamps, or even 300 watt Xenon lamps. For the line powered light sources it is necessary to use a fiber optic light guide (or a liquid light guide) to connect the light source to the borescope. 
The amount of light you need depends on the size of the cavity that you need to illuminate, the amount of Illumination fiber in the borescope and the sensitivity of the detector, be it a camera or your eye. For illuminating most machined metal parts, metal tubes, rifle barrels, etc. a simple hand held portable light source can be used very effectively. When viewing larger cavities such as engine cylinder, large casting, inside of walls, fuel tank, oxygen tanks, etc, then you will need a higher-powered light source.
More details on borescope light sources can be found here

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