If you look closely at a single optical fiber, you will see that it has the following parts:

• Core - Thin glass center of the fiber where the light travels
• Cladding - Outer optical material surrounding the core that reflects the light back into the core
• Buffer coating - Plastic coating that protects the fiber from damage and moisture

Optical fibers come in two types:

• Single-mode fibers
• Multi-mode fibers

Some optical fibers can be made from plastic. These fibers have a large core (0.04 inches or 1 mm diameter) and transmit visible red light (wavelength = 650 nm) from LEDs.

How Does an Optical Fiber Transmit Light?

Diagram of total internal reflection in an optical fiber

Advantages of Fiber Optics

• Less expensive - Several miles of optical cable can be made cheaper than equivalent lengths of copper wire. This saves your provider (cable TV, Internet) and you money.

• Thinner - Optical fibers can be drawn to smaller diameters than copper wire.

• Higher carrying capacity - Because optical fibers are thinner than copper wires, more fibers can be bundled into a given-diameter cable than copper wires. This allows more phone lines to go over the same cable or more channels to come through the cable into your cable TV box.

• Less signal degradation - The loss of signal in optical fiber is less than in copper wire.

• Light signals - Unlike electrical signals in copper wires, light signals from one fiber do not interfere with those of other fibers in the same cable. This means clearer phone conversations or TV reception.

• Low power - Because signals in optical fibers degrade less, lower-power transmitters can be used instead of the high-voltage electrical transmitters needed for copper wires. Again, this saves your provider and you money.

• Digital signals - Optical fibers are ideally suited for carrying digital information, which is especially useful in computer networks.

• Non-flammable - Because no electricity is passed through optical fibers, there is no fire hazard.

• Lightweight - An optical cable weighs less than a comparable copper wire cable. Fiber-optic cables take up less space in the ground.

• Flexible - Because fiber optics are so flexible and can transmit and receive light, they are used in many flexible digital cameras for the following purposes:
  • Medical imaging - in bronchoscopes, endoscopes, laparoscopes
  • Mechanical imaging - inspecting mechanical welds in pipes and engines (in airplanes, rockets, space shuttles, cars)
  • Plumbing - to inspect sewer lines

Steps for Ray Diagram of Concave mirrors

1. From the tip of the object, draw a line parallel to the principal axis to the mirror. Then, draw another line from the tip of the object to the mirror but this time, the line must pass through the focal point.

3. The point where the two rays of reflection intersect is where the tip of the image is. Just draw a perpendicular line connecting the point of intersection and the principal axis. And that's how to make a ray diagram.. Easy, ayt?

1. Draw a line parallel to the principal axis from the tip of the object to the mirror. Draw another line (that if extended, would pass through the focal point, which in this case, would be on the other side of the mirror) to the mirror.
2. As by the two laws of reflection of convex mirrors, from the first incident ray, draw a line straight up or perpendicular to the principal axis. From the point of the second incident ray touching the mirror, draw a line parallel to the principal axis.
3. To get an intersection, extend the rays.

4. The point of intersection is the tip of the object. Just draw a perpendicular line connecting it and the principal axis.
Steps for Ray Diagram of Converging Lenses

1. Draw the first ray parallel to the principal axis. Draw the second ray passing through the vertex. Draw the third ray passing through the focal point in front of the mirror.

2. Based on the three laws of refraction for converging lenses, the ray of refraction for the first ray of incidence must pass through the focal point at the back of the lens, the second ray of incidence must travel a straight line and the third ray of incidence must form a ray of refraction parallel to the principal axis.
3. The point of intersection is the tip of the object. Just draw a perpendicular line connecting the point of intersection and the principal axis.
Steps For Ray Diagram of Diverging Lens

1. From the tip of the object, draw the first ray parallel to the principal axis. Draw a second ray that if extended would pass through the focal point of the back side of the mirror. Draw a third ray passing through the vertex.
2. Based on the three laws of refraction for diverging lenses, the ray of refraction for the first incident ray should be going up, tilted to the back side and if extended, would pass through the focal point of the front side of the lens. For the second ray, its ray of refraction must be parallel to the principal axis. For the third ray, it just goes like a straight line.

3. To get an intersection, jut extend the rays of refraction, that connect the intersection to the principal axis with a perpendicular line. Now, you're done with your ray diagram!