(N/A) Optical fibres are extensively used in the medical field for a technique known as endoscopy.
$1$. An endoscope is a medical instrument consisting of a bundle of optical fibres that can be inserted into the body to view internal organs.
$2$. The principle behind this is $Total Internal Reflection$ $(TIR)$.
$3$. One bundle of fibres carries light into the body to illuminate the internal area,while another bundle transmits the reflected light back to the doctor's eyepiece or a camera.
$4$. This allows doctors to perform minimally invasive surgeries and examine internal structures like the stomach,intestines,or lungs without making large incisions.