Light as electromagnetic radiation

The laser light sources and variants of intense pulsed light (IPL) discussed here mainly use visible to infrared light with wavelengths in the range of 400 nm to 1200 nm (nanometers). The CO2 laser (10600 nm) and the Er:YAG laser (2940 nm) use other wavelengths outside this spectrum.

The wavelength has a direct effect on the way the light pulse works on the human body, as we will see in the following section.

Electromagnetic radiation is quantized into photons. This means that the amount of electromagnetic radiation of any frequency is equal to one (1) photon.

When a photon is absorbed – in our case by the patient’s skin – its energy is converted into heat. The absorption of photons, or light energy, is the basis for all photoepilation procedures and builds on these interactions between light and tissue. The energy of electromagnetic radiation is measured in joules (J).

Another important factor is the so-called fluence (energy density) or dose. It is the amount of emitted energy delivered to a given area and is measured in J/cm2.

Finally, the duration of exposure of the light to the skin is called pulse duration.

These are the individual factors and parameters that influence the success of treatment when using light energy in the medical-technical field and whose precise coordination must be monitored.