Date: 03/03/2014 (Monday)
Title: Research and findings
In this week I’m continuing my research about type of laser. This time the research is going into detail and more focusing about the laser pointer or diode and photoresistor.
LASER
A laser creates light by special actions
involving a material called an "optical gain medium". Energy is put into this
material using an 'energy pump'. This can be electricity,
another light source, or some other source of energy. The energy makes the
material go into what is called an excited state. This means the electrons in
the material have extra energy, and after a bit of time they will lose that
energy. When they lose the energy they will release a photon (a
particle of light). The type of optical gain medium used will change what
colour (wavelength) will be produced. Releasing photons is the
"Emission of Radiation" part of LASER.
There are many types of lasers available for research, medical, industrial, and commercial uses. Lasers are often described by the kind of lasing medium they use - solid state, gas, excimer, dye, or semiconductor. For my project i use semiconductor laser below is the diagram of the laser:-
There are many types of lasers available for research, medical, industrial, and commercial uses. Lasers are often described by the kind of lasing medium they use - solid state, gas, excimer, dye, or semiconductor. For my project i use semiconductor laser below is the diagram of the laser:-
Lasers, sometimes called diode lasers, are not solid-state
lasers. These electronic devices are generally very small and use low power.
They may be built into larger arrays, e.g., the writing source in some laser
printers or compact disk players.
PHOTORESISTOR
Photo resistors, also known as light dependent resistors
(LDR), are light sensitive devices most often used to indicate the presence or
absence of light, or to measure the light intensity. In the dark, their
resistance is very high, sometimes up to 1MΩ, but when the LDR sensor is
exposed to light, the resistance drops dramatically, even down to a few ohms,
depending on the light intensity. LDRs have a sensitivity that varies with the
wavelength of the light applied and are nonlinear devices. They are used in
many applications but are sometimes made obsolete by other devices such as
photodiodes and phototransistors. Some countries have banned LDRs made of lead
or cadmium over environmental safety concerns.
