For many years we have been told a simple public health message: “Wear sunscreen, especially during the summer.” It is well-intentioned advice, but as a physicist I have always found it rather unsatisfying. Nature is rarely that simple, or linear (In fact, in this universe, ‘linear’ is the exception rather than the rule!). If we… Continue reading The physics of sunscreen, SPFs and the energy flow…
Tag: science
If a Nd:YAG laser can only produces 1064 nm light… where do all the other wavelengths come from?
It’s an excellent question. Most laser users know that a KTP crystal converts 1064 nm into 532 nm by “frequency doubling”. But what about the other wavelengths—585 nm, 650 nm and the various colours advertised by some manufacturers? Is the laser somehow producing entirely new wavelengths? Well… yes. But not quite in the way many… Continue reading If a Nd:YAG laser can only produces 1064 nm light… where do all the other wavelengths come from?
Annual BMLA meeting in May 2026 – my talks
Next week on May the 7th and 8th I will be attending the BMLA meeting in Solihull near Birmingham. I will be giving two talks, one in the morning of Friday the 8th, around 9:45am. This talk is entitled: “Determining the optimum fluences required to irreversibly destroy hair follicles using numerical analyses.” In this talk… Continue reading Annual BMLA meeting in May 2026 – my talks
How far does light scatter in the skin?
When light enters the skin, it immediatley begins to scatter. This is the process where photons are absorbed by atoms (making electrons ‘excited’), and new photons are emitted shortly after (when those electrons ‘de-excite’). Inevitably, they leave the atom in a different direction to their original direction. This is called ‘scattering’. Consequently, the light spreads… Continue reading How far does light scatter in the skin?
Laser safety glasses – what does ‘DIRM’ mean?
You know I keep banging on and on about safety glasses and how important they are (you only have one pair of eyes!!). I have written a number of times about this topic and how to understand the text on your safety glasses (https://mikemurphyblog.com/2024/02/29/laser-safety-glasses-and-how-to-read-them/). Yet, I find that people still don’t know much about this… Continue reading Laser safety glasses – what does ‘DIRM’ mean?
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