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| Home > Industrial Vision > To know more about it | |||||||||||||||
| To know more about it | |||||||||||||||
DEFINITION OF AN ENDOSCOPE An endoscope is a probe (flexible or rigid), and usually of small diameter, that makes it possible to see into inaccessible areas. To do this, an endoscope has two distinct functions: The Vision function and the Illumination function. The Vision function is achieved using an optical or opto-electronic system made up of: - A lens - Image transmission - A display unit (eyepiece or video monitor) The Illumination function is usually obtained using a lighting system made up of either: - A light generator - A lighting cable connecting the generator to the handle of the endoscope - A lighting fibre optic bundle integrated into the endoscope and providing transmission of the light between the handle and the end of the probe. or: - One or more mini lamps at the end of the probe. RIGID ENDOSCOPES Principle : The image of the object, delivered by the lens, is transmitted to the eye by lenses. Different types of lens are used depending on the dimensions of the endoscope: - Achromatic or doublet lenses for endoscopes above Ø 3 mm - SELFOC lenses for endoscopes below Ø 3 mm. This is an optical monofibre with a diameter of between 0.35 mm and 2.7 mm and of a fixed length. A variation in the index gradient obtained by doping allows image transmission in the form of waves. These lenses make it possible to produce small-diameter endoscopes. Structure of a rigid endoscope  Main characteristics of endoscopes
FLEXIBLE ENDOSCOPES Principle : The image of the observed object, delivered by the objective, is transmitted to the eye of the observer by a coherent optical round bundle ordered in a consistent way. An image formed on the surface of the entry section will be transmitted point by point to the surface of the exit section. Traditional fibrescopes Traditional fibrescopes use fibre optic bundles. The diameter of each fibre varies from 7 to 11 microns according to the manufacturer. The maximum length of the bundles does not exceed 6 metres. Microfibrescope Microfibrescopes use a technology based on silica fibre bundles. These bundles have the following specific features: - Very small bundle diameter from 0.35 mm. - Single fibre of 3 microns giving high resolution up to 30,000 points in a very small diameter. - Long bundle length of up to several tens of metres thanks to the low attenuation of the fibres. This technology makes it possible to produce microfibrescopes with a diameter of less than Ø 1 mm and considerable working lengths. Structure of a fibrescope  Main characteristics of fibrescopes
VIDEOENDOSCOPES The image of the observed object, delivered by a objective, is transmitted by a CCD chip placed in the furthest end of the probe to a video monitor. Current video endoscopes are produced with high-resolution colour CCD chip. Technological developments make it possible to reduce their size and so to reduce the size of the video probes. Currently the smallest CCDs are 1/6" and the probes produced are Ø 6 mm. In the near future, 1/10" sensors will be available, making it possible to produce Ø 4 mm probes. As for fibrescopes, the lighting is produced using optical fibres connected to a white light generator (Halogen, Xenon) or by halogen micro-lamps fitted in the furthest end of the probe. Structure of a video endoscope A video endoscope has 3 parts and a main accessory: - A probe - A control unit - A light generator - A video monitor Characteristics of a video endoscope
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