3 + 4 Flashcards
What are optical fibers?
Long, thin strands of glass or plastic that can light undergoes total internal reflection from one end to other end
Advantage of optical fibers
Light can travel very long distance without significant loss
Describe endoscopy (application in medicine)
It use optical fibers to create total internal reflection that conducts light down a tube
The outer layer has lower refractive index than the core which makes total internal reflection when light enters
- > endoscopes are inserted directly into the organ or orifices
- > to examine the interior of a hollow organ or cavity of the body.
What is optical path length?
= Distance traveled of light x refractive index (of the medium the light propagates)
What is spectral reflectance?
the proportion of light that a surface reflects at each wavelength
3 types of reflection
Specular
Diffuse
Mixed
What is inelastic scattering?
the scattered light has the different wavelength than the incident one
Describe specular reflection
(1) Smooth surface
(2) Incident angle = reflected angle
Describe diffuse reflection
Rough surface
Irregular reflection
Describe mixed reflection
Combination of specular reflection and diffuse reflection
2 types of light scattering
(1) Elastic scattering
(2) Non-elastic scattering
What is elastic scattering?
the scattered light has the same wavelength than the incident one
What is What is Ray-leigh scattering?
elastic scattering from small particles such as atoms or molecules, resulting in scattered radiation that occurs in all directions uniformly.
-> Rayleigh scattering is wavelength dependent with shorter wavelengths being more scattered.
What is Raman scattering?
the Raman scattering depends upon the polarizability of the molecules
-> the inelastic scattering due to energy transition between light and material.
What is Mie-scattering?
If the particle size is comparable to the wavelength
- the scattering becomes independent of the wavelength.
(Water drops in the clouds scatters any wavelength and this is the reason fo their white or gray color)
State law of reflection
The incident ray, the normal of incidence and the refracted ray are in 1 plane
Angle of reflection = angle of incidence
