Frequency is the number of occurrences of a repeating event per unit of time. Thus, the number of times you laser can pulse in one second. The formula for frequency is f = 1/time, and is given in hertz (Hz).
This may seem theoretical and not really worth knowing, but it does have a significant influence in how your client experience the treatment and the recovery time afterwards.
When you do a photothermal treatment the objective is to create heat in the target tissue and the heat will generate the result. Between pulses the heat dissipate and this has a significant influence in the sensation associated with the treatment.
Rapid pulsing, or high frequency pulsing, leads to the phenomenon of heat build-up. If the pulses are spread over a small area, close to each other, the total area has an increase of temperature. This means that the ‘burning’ sensation lingers longer with the previous pulse, while the area where the next pulse will be is already preheated. This very concept is the reasoning for the high frequency, low fluence technique known as ‘pain free’ hair removal.
With the high frequency, low fluence technique the energy is greatly reduced with the idea that multiple pulses in the same area will create an accumulative heat build-up that is enough to destroy the dermal papilla, but each individual pulse is less intense and less painful. This seems to be the case as long as you have a sufficient density of the target molecule.
With the traditional high fluence technique of hair removal, going faster leads to an increase in pain for your client during the treatment and an increased recovery time afterwards. Slowing down during a treatment allows for more effective cooling during the treatment, which will have a direct effect on the client’s comfort and tolerance level. This also leads to a reduction in the recovery time after a treatment and elimination of possible side effects.
The same benefits of a slower treatment are observed with ablative treatments, like a skin peel. The treatment in itself becomes more tolerable to the client, while the recovery time can be significantly reduced.
Sometimes the only way to speed-up results is by slowing down.