LAgirl
How does spot size effect depth of penetration? I thought depth of penetration was set by the laser wavelength and was not adjustable. With a constant J/cm2, wouldn’t a large spot size just make the procedure go quicker? For instance, given a constant fluence, what is the difference between a 10 and 20 mm spot size other than speed of treatment?
galvaniczap,
As I understand, a larger spot size is more likely to kill a given hair as the laser wave is more likely to engulf it( like a cone) below the skin.
One study shows that a 18mm spot size is 10% more effective than a 9mm spot size when the same fluence was used for both. The added advantage of reduction in treatment time bodes well for larger spot size machines.
SAK is right. There is a cone effect. Google it and you’ll find specific info on it with photos. SSLHR explains it well in detail on this forum too, so you can search for his posts too.