Page 65 - Lasers and IPLs in Medical/Aesthetic Applications v1.2
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Chapter 1 – Fundamentals of Medical/Aesthetic Lasers and IPLs v1.2
Repetition Rate
● Many devices allow you to choose a repetition rate so that a train of pulses will be fired when you press the footswitch (or press the hand-switch).
● Some lasers will produce rep rates up to 10 or 20 pulses per second. This is usually expressed as Hertz (Hz).
● One shot per second is one Hertz. So, some lasers may go up to 20 Hz but the vast majority of IPLs cannot go much faster than 1 or 2 Hz due to constraints in their designs. This is usually due to overheating problems in the lamp cavity.
 Note:
Sometimes you may see a device offering a rep rate of 0.5 Hz – this means one shot every two seconds. We’ve even seen devices with rep rates as low as 0.2 Hz;
that’s one shot every five seconds!!
On the other side of the coin, you may come across lasers which offer high rep rates. For example, we have seen Q-switched Nd:YAG lasers as high as 25 Hz. This may sound attractive but, in reality, this is difficult to use in the real world.
Most people struggle to operate these lasers above 10 Hz simply because it’s too fast to cope with clinically! The question is then, are you paying for a laser with a speed you really can’t use?
 • The choice of repetition rate is entirely down to the laser/IPL operator. It doesn’t really affect the clinical outcome. However, a slow rate is desirable when treating small, or intricate areas. However, if you are removing hair on legs, or treating a large tattoo, you will be better will a faster rep rate, otherwise you will be treating for a long time.....
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Chapter 1 LEVEL A Fundamentals of Lasers/IPLs
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