Laser safety management (medical and cosmetic applications)
'Core of knowledge' course notes, technical information
Common Machine Variables
Stand by/Ready
In "stand by" mode, the machine is fully powered but the "fire" button/footswitch is disabled. The machine should be placed in ready mode, only when the laser is in place and treatment is about to begin.
Exposure time
The duration of exposure can sometimes be set on laser equipment. This can also be referred to as pulse length or pulse width. For multiple pulse machines, the pulse delay (time between pulses can also be varied)
Energy (radiant energy)
This is basically the amount of light output set. The greater the energy, the greater the heating effect of the beam. This is measured in Joules, J. Sometimes this is expressed as radiant exposure which is the energy per unit area. This is sometimes also defined as "fluence" on some laser equipment, unit: J/cm2
Power (radiant power)
For machines capable of a continuous laser output, the power is the amount of energy per unit time. This is measured in Joules per second, or Watts, W. Again, this can be expressed as power per unit area, or Irradiance (W /m2)
Wavelength
Some laser machines operate at several different wavelengths. Sometimes these are designed to be active all at the same time or on other machines, the wavelength can be selected. For example, many Nd:YAG lasers can be operated at 1064nm, or 532nm. For an IPL, a series of filters are often used to change the spectrum of the output depending upon the treatment.
Repetition frequency
For pulsed lasers, the number of pulsed per unit time can be set. This is typically measured in Hertz (Hz), or pulses per second.
Aiming beam / pilot beam
Many lasers make use of a low power aiming beam of a different colour. Sometimes the intensity of the beam can be varied or the beam can be turned off altogether.
Spot size
In some cases, the focusing or spot size (area of beam at a set distance) of the laser can be varied. In the case of an IPL, different size light guides may be used.
Units
Acronyms
