Nowadays, it is possible to purchase Q-switched Nd:YAG lasers with a single YAG rod, or with two rods. So, what is the difference and is it important? To understand why a laser might have two rods instead of one we should look at the basic design of a laser first. Basic laser cavity A… Continue reading Single or Double Rod Nd:YAG Lasers?
TRTs I’ve had a number of enquiries about my article on the relevance of thermal relaxation times in photothermal treatments. They were asking for clarification. So here goes…. Thermal relaxation time (TRT) describes how quickly an object loses heat energy. Typically, it is the time taken for the temperature of an object to drop… Continue reading More on Thermal Relaxation Times
The theory which has underpinned many skin-laser treatments since 1981 is called ‘Selective Photothermolysis’. It is based on matching the laser wavelength to the absorbing chromophore. It also matches the pulse duration of the laser to the thermal relaxation times of those targets. However, there is a problem with this approach. The thermal relaxation… Continue reading Thermal Relaxation Time – what is wrong with it?
And here it is, in black and white…. This wonderful little equation describes how hair, blood, collagen or any other protein denatures as a function of time and temperature. It is important to understand how this works if you want to treat these proteins properly. Most people have never even heard of it, yet… Continue reading Tissue denaturation – the process
New Advanced Laser-Tissue Interactions Course Finally, a course designed to outline a deeper understanding of the processes involved when applying laser/IPL energy to the skin. Topics include: Light transport in tissues; Thermodynamic effects; Selective Photothermolysis; Tissue denaturation; Arrhenius damage integral….. And more! Using recently developed computer models this course describes the more important processes… Continue reading Advanced Laser-Tissue Interactions Course
Article People kept asking me how radio frequency (RF) worked in the treatment of skin conditions. It’s pretty simple, really. It’s just electrical heating – nothing new! But, there appears to be a lot of, shall we call it, ‘mis-information’ out there, so I wrote this piece. I’ve also included some info on ‘Heat… Continue reading “Thermal Energy Levels” – my description of how RF operates in the skin
via Variable pulsewidth vascular system for dermatology | (1994) | Gustafsson | Publications | Spie This report describes the world’s first IPL system, developed by Morgan Gustafsson in the early 1990s. Back then we didn’t call it IPL – that name came later. Morgan approached me at an ASLMS conference after I gave a… Continue reading Variable pulsewidth vascular system for dermatology | (1994) | Gustafsson | Publications | SPIE