Laser Light

Laser, a device that stimulates atoms or molecules to emit light at particular wavelengths and amplifies that light, typically producing a very narrow beam of radiation. A laser is an unusual light source. It is quite different from a light bulb or a flash light. Lasers produce a very narrow beam of light. This type of light is useful for lots of technologies and instruments—even some that you might use at home.

Work of a Laser light

Laser” is an acronym for light amplification by stimulated emission of radiation. … When they return to their normal or “ground” state, the electrons emit photons (particles of light). These photons are all at the same wavelength and are “coherent,” meaning the crests and troughs of the light waves are all in lockstep.

What makes laser so special?

Lasers produce a narrow beam of light in which all of the light waves have very similar wavelengths. Because laser light stays focused and does not spread out much (like a flashlight would), laser beams can travel very long distances. They can also concentrate a lot of energy on a very small area.

Principle of Laser light

A laser emits a beam of electromagnetic radiation that is always monochromatic, collimated and coherent in nature. Lasers consist of three main components: a lasing medium (solid, liquid or gas), a stimulating energy source (pump) and an optical resonator; and have a wide variety of uses in clinical medicine.

Characteristics of a Laser Radiation


Monochromaticity
Directionality
Coherence
Brightness
High Output

Unique Property of Laser
Coherence


Coherence is one of the unique properties of laser light. It arises from the stimulated emission process which provides the amplification. Since a common stimulus triggers the emission events which provide the amplified light, the emitted photons are “in step” and have a definite phase relation to each other.

Different colours of Laser

Blue lasers are also more dangerous than red and green ones because blue is more easily absorbed by pigments in the retina and thus more damaging to it. Blue and violet lasers can be particularly dangerous because human eyes are least sensitive to these colour frequencies. Laser pointers that are directed into the sky can distract or temporarily blind pilots of passing aircraft.

Applications / Uses


Lasers are used in optical disk drives, laser printers, barcode scanners, DNA sequencing instruments, fiber-optic, semiconducting chip manufacturing (photolithography), and free-space optical communication.
Lasers have many uses in medicine, including laser surgery (particularly eye surgery), laser healing, kidney stone treatment, ophthalmoscopy and cosmetic skin treatments such as acne treatment, cellulite and striae reduction, and hair removal. Lasers are used to treat cancer by shrinking or destroying tumours or precancerous growths. 
In Industry it is used for cutting, welding, heat treatments, 3D printing, 3D scanning , making parts ( engraving and bonding).


In Law enforcement for fingerprint detection in forensic identification field.
Hobbies / entertainment / Communication: Lasers are used in optical disk drives, laser printers, barcode scanners, DNA sequencing instruments, fiber-optic, semiconducting chip manufacturing (photolithography), and free-space optical communication, fiber optic communication.


Microscopy
Photochemistry
Laser Cooling

Negative Effect of Laser


Improperly used laser devices are potentially dangerous. Effects can range from mild skin burns to irreversible injury to the skin and eye. The biological damage caused by lasers is produced through thermal, acoustical and photochemical processes.

Risks of Laser hair removal


Mild swelling around the hair follicles.
Pigment changes may occur, especially in those with darker skin – these changes are usually temporary.
Slight redness of the skin.
Temporary irritation resulting in blistering, crusting, scarring or other changes in skin texture.

Risks (Skin related)


Skin is the largest organ of the body and, as such, is at the greatest risk for coming in contact with the laser beam.  The most likely skin surfaces to be exposed to the beam are the hands, head, or arms.
Lasers can harm the skin via photochemical or thermal burns.  Depending on the wavelength, the beam may penetrate both the epidermis and the dermis.  The epidermis is the outermost living layer of skin.  Far and Mid-ultraviolet (the actinic UV) are absorbed by the epidermis.  A sunburn (reddening and blistering) may result from short-term exposure to the beam.  UV exposure is also associated with an increased risk of developing skin cancer and premature aging (wrinkles, etc) of the skin.


Risks (Eyes related)


Light causes biological damage through both temperature effects due to absorbed energy and through photochemical reactions.  The chief mode of damage depends on the wavelength of the light and on the tissue being exposed. Laser irradiation of the eye may cause damage to the cornea, lens, or retina, depending on the wavelength of the light and the energy absorption characteristics of the ocular tissues.

Laser light related experiment:-

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