Endoscopy is a medical technique that lets doctors see inside the human body using a special tool called an endoscope. Unlike other imaging techniques that use radiation or sound, endoscopy involves inserting the endoscope directly into the body. This makes it an invasive procedure. Fibre optics are used in endoscopes to transmit light and images, which helps doctors see inside the body more clearly. Endoscopy is an important tool for diagnosing and treating many medical conditions.

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Is fibre optics used in endoscopy?

Fibre optics is a technology that is used in endoscopy. It involves using thin, flexible, and transparent fibres that are only slightly bigger than a human hair to transmit light. In fibre optics, light is transmitted through a core that is surrounded by a transparent cladding material with a lower index of refraction. The way light is transmitted through fibre optics is based on the principle of total internal reflection. This technology is crucial for endoscopy, as it allows doctors to see inside the body using endoscopes. The use of fibre optics in endoscopy has revolutionized the field of medical imaging, making it easier to diagnose and treat many medical conditions.

The total internal reflection principle

Total internal reflection is an optical phenomenon that happens when light waves reach the boundary between two media, but instead of refracting to the opposite medium, they are completely reflected back to the initial medium. This happens because the opposite medium has a higher refractive index than the initial medium. Refractive index is a number that shows how fast light can travel through a medium. The speed of light in a medium and the refractive index are inversely proportional. We can calculate the refractive index of a medium with an equation that includes the speed of light in a vacuum and the phase velocity of light in the medium. To determine if total internal reflection occurs, the angle of incidence must be greater than the critical angle, which can be calculated using an equation that includes the refractive indices of both media. If the angle of incidence is less than the critical angle, the wave will refract to the opposite medium. If it is equal to the critical angle, the wave will continue on its way in alignment with the boundary. If the angle of incidence is greater than the critical angle, total internal reflection occurs, and the wave will reflect back to the initial medium.

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When using endoscopes with fibre optics, a light source in the tip of the endoscope illuminates the passageways. The light is reflected from the passageways back into this tip. Light is guided by a step-index structure inside the optical fibre that induces total internal reflection and directs coupled light from one end to the other without loss. For this to happen, the refractive index of the fibre core material (n1) must be greater than that of the fibre cladding material (n2).

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When using fibre optics in an endoscope, light with an incidence angle greater than the maximum acceptance angle θa will be partially refracted outside of the fibre, while light with an incidence angle less than θa will be partially refracted inside the fibre. After several encounters with the core-cladding interface, the residual partly reflected light is finally lost. The requirement for 100% internal reflection at the core-cladding contact determines the maximum acceptance angle θa, which can be found using an equation that includes the critical angle θc. The acceptance angle θa is an important characteristic of fibre optics because light will enter and exit the optical fibre with the same angle with regard to the fibre's central axis. This means that in a curved fibre, θa = θa'. Light waves that reflect from the passageways of the human body and enter the optical fibres in an endoscope travel through the optical fibres with total internal reflection, and the light exits the optical fibres in the same way it entered them. This allows for the transfer of an image for a viewer to examine.

What are the applications of endoscopy?

Endoscopy has a wide range of applications in medical physics beyond its use in surgeries. One common use is to examine the passageways of the human body to detect abnormalities. Other applications include panendoscopy for plastic surgery, orthopaedic surgeries such as knee and hand surgery, examining the foetus and amnion during pregnancy, examining the female reproductive system, and looking into the interior of the ear. These applications help doctors and medical professionals to diagnose and treat medical conditions more effectively and with less invasiveness than traditional surgical methods. Endoscopy continues to be an important tool in the field of medical physics, providing a non-invasive way to see inside the human body and to detect medical problems in their early stages.

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To summarize, endoscopy is a procedure that allows doctors to examine the body's passageways and is also used in various surgical procedures. It is different from other imaging techniques as it uses an endoscope inserted directly into the human body, making it invasive. Optical fibres are flexible and transparent with a diameter just a little bigger than a human hair, making them ideal for transmitting light. The transmission of light in fibre optics on the total internal principle use to see the Endoscopy has various applications in medical physics, including examining the foetus and amnion during pregnancy and looking inside the human ear.

Fibre Optics and Endoscopy

How are fibre optics used in endoscopy?

Fibre optics is used in endoscopy, and it is primarily used for transmitting light. In fibre optics, a core is usually surrounded by a transparent cladding material with a lower index of refraction. The way light is transmitted in fibre optics, which allows doctors to use endoscopes to see the body’s interior, depends on the total internal reflection principle.

What is fibre optic endoscopy?

Fibre optic endoscopy is an imaging technique that uses fibre optic endoscopes in order to look into the passageways of the human body.

What is the disadvantage of endoscopy?

One disadvantage of endoscopy is that it is an invasive procedure unlike other imaging techniques based on radiation or sound.

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