Page 46 - Lasers and IPLs in Medical/Aesthetic Applications v1.2
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Chapter 1 – Fundamentals of Medical/Aesthetic Lasers and IPLs v1.2
● As a direct consequence of this slowing, the wavelength shortens. The frequency cannot change – it is fixed by the source of the light. So, the wavelength must change to keep the physics right!
When Einstein was asked ‘What is light?’, he (allegedly) responded “I don’t really know! Anyone who says they do, is lying!!”
So, it’s not just us.....
Energy & Energy Density (or ‘Fluence’)
● All light has an energy. This is why we can see it in the first place! Energy is the stuff that is used to make things work. (In physics, ‘work’ is the physical change or alteration of a substance.) If there was no energy then nothing would work! These days it is usually measured in joules (expressed as a capital ‘J’) but many people still refer to the old term – ‘calories’.
● Energy exists in a number of forms – chemical, thermal (heat), kinetic (motion), potential, gravitational and nuclear, plus others. Click here for an interesting video explaining energy. Or watch this video which shows how heat energy flows.
● Most people understand the concept of energy when related to food or drink. If you are on a diet you will probably restrict your calorie (Joule) intake. We all know that this will eventually result in weight loss.
● However, what you may not have realised is that weight loss/gain is directly due to the chemical energy (or calories or joules) contained within the food/drink. This energy is stored within the sugars in the food and drink we consume. Essentially, sugars are energy sources for all living creatures.
When we treat the skin with lasers or IPLs we usually deliver around 20-100 Joule of energy per pulse, usually less.
How much energy do you need to make a cup of tea or coffee? Answer here...
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Chapter 1 LEVEL A Fundamentals of Lasers/IPLs
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