Laser works on principle of selective photothermolysis.
Leon Goldman started laser use in dermatology first time after discovery of lasers.
Flashlamps are intense pulsed light ( IPL) devices..
These lights use cut off filters so as to provide broad range of wavelengths of electromagnetic spectrum .
IPL can be available for versatile use in dermatology ..
Lasers are collimated monochromatic light energy delivered at specific wavelength with either continuous mode or pulsed waves with pre- determined pulse duration to destroy specific target.
Photons are the quantum of light energy. When photons are stimulated in excited medium they are capable of generating other photons exponentially. These stimulated emission of photons through the mirror with reflectivity <100% concentrated on lens to form laser beam on fiber.
So the name: LASER: light amplification by stimulated emission of radiation .
Selective photothermolysis :
Laser destroys the target inside skin very specifically without damage to adjacent tissue
Basic parameters of optical radiation:
Energy = power * time
Intensity= power/ area
Fluence = power* time /area
Radiant exposure for IPL is determined by size of applicator and energy of radiation.
Energy is expressed in terms of joules.
Fluence is expressed in J/cm2.
Longer the wavelength between 400-1200 nm the more deeper the penetration in the skin.
Lasers are classified as
1)Continuous wave (>0.2 s)
2) pulsed mode (0.2 s-1 micro second)
3) quality switch lasers ( 1 micro second - 1 ns)
Interaction of radiation with skin:
When radiation penetrate the skin the following process can happen:
1) scattering
2) reflection
3) absorption
So when we decide the laser wavelength we should take these optic physics into consideration.
Eye safety is must because of reflection of light.
UVR and Infrared light can not be visible to eye so more chance of damage without perception.
Possible eye injuries range from cornea damage, retina injury, cataracts to permanent blindness.
No comments:
Post a Comment