2. Laser is an acronym for light amplification by stimulated emission radiation
Lasers do not occur in nature but ways have been figured to artificially create this special type of light.
Lasers can move at a speed of 299,792,458 m/s (speed of light in vacuum)
Lasers are used in laser printers, barcode scanners, DNA sequencing, instruments, skin treatments,
cutting and welding materials and etc.
INTRODUCTION
3. How lasers are produced
For a laser to be produced, the lasing
medium is “pumped” to get the atoms
into an excited state.
Typically, very intense flashes of light or
electrical discharges pump the lasing
medium and create a large collection of
excited-state atoms
In general, the atoms are excited to a
level that is two or three levels above the
ground state
Once the lasing medium is pumped, it
contains a collection of atoms with some
electrons sitting in excited levels
4. How lasers are produced
Just as the electron absorbed some amount of energy to reach this excited level, it can
also release this energy
This emitted energy comes in the form of photons (light energy)
The photon that any atom releases has a certain wavelength that is dependent on the
energy difference between the excited state and the ground state
If this photon should encounter another atom that has an electron in the same excited
state, stimulated emission can occur.
The other key to a laser is a pair of mirrors, one at each end of the lasing medium.
The mirror at one end of the laser is "half-silvered," meaning it reflects some light and
lets some light through. The light that makes it through is the laser light
5. Characteristics of a laser
The laser light produced has the following properties
The light released is monochromatic: contains one specific wavelength (one specific colour)
The light released is coherent: each photon moves in line with the other. Thus, they are
directional
The light is very directional: . A laser light has a very tight beam and is very strong and
concentrated. A flashlight, on the other hand, releases light in many directions, and the light is very
weak and diffuse.
6. Types of lasers
Lasers are categorized based on the type of medium they use.
Solid-state lasers: These lasers are made out of a solid medium like ruby or crystalline
with a flash tube wrapped around it to excite electrons
Gas lasers: These lasers are typically made out of helium or helium-neon and produce
our characteristic red laser light
Liquid lasers: These lasers use liquid dyes like rhodamine in a liquid solution as their
medium.
Semiconductor lasers: These lasers are cheap to produce and are found in a variety of
electronic devices from laser printers to barcode scanners
7. Laser as a temperature measuring device
Laser thermometers are actually infrared thermometers. The laser
simply provides a means to aim the thermometer
IR thermometers use a series of lenses and mirrors to focus the
emitted infrared energy onto a detector called thermopile
The detector converts the emitted infrared energy into an electrical
signal, which the thermometer turns into a digital temperature
reading
IR thermometers are used to measure the temperatures of very hot
objects, objects in hard-to-reach places, hazardous materials and in
food manufacturing to monitor the temperature of frozen and hot
foods.
For an accurate temperature reading, the object being measured
should fill the field of view of the IR thermometer
8. Advantages of lasers
IR thermometers are convenient; the noncontact feature allows temperature
measurements to be taken without touching the product being tested
The response time (detection to display) of an IR thermometer is typically about
one-half second which shows how fast it is.
9. Disadvantages of lasers
IR thermometers only measure surface temperature and do not measure through
glass, liquids or other transparent surfaces.
They also may require adjustments depending upon the surface being measured
especially if it is a highly reflective surface.
IR thermometers can be temporarily affected by frost, moisture, dust, fog, smoke,
other particles
