In today's episode, Lisa and Mike turn up the energy - literally! They dive into the fascinating world of lasers and IPL treatments, unpacking the science behind spot size, fluence, depth of penetration, and wavelengths. When Emma, a curious Level 4 student, asks about how energy delivery changes with different spot sizes, Lisa and Mike fire back with laughs, analogies, and plenty of light-based wisdom. Along the way, they break down why fluence matters, how scattering shapes results, and why pre-cooling can be the secret to a pain-free zap. KEY TAKEAWAYS Fluence, defined as energy per area (joules per square centimetre), remains constant across different spot sizes. However, the total energy delivered varies significantly based on the spot size, with larger spots delivering more total energy. When light enters the skin, it scatters, which affects the fluence at different depths. The scattering can lead to an increase in fluence just below the skin surface due to backscattering, which can exceed the incident fluence. Different wavelengths penetrate the skin differently, with red light penetrating deeper than blue or green light. However, the presence of scattering in the skin can alter the effectiveness of these wavelengths. Increasing fluence at the skin surface raises the temperature in the epidermis, which can trigger pain receptors. Pre-cooling the skin before treatment can help mitigate pain by lowering the baseline temperature. Understanding fluence is crucial for effective laser treatments, as it directly influences the temperature rise in the target tissue, which is essential for achieving desired treatment outcomes. BEST MOMENTS "When you set up your laser or IPL to deliver a particular fluence, then at every point in that spot the fluence is the same, or it should be the same." "So then how does the small spot work so well? Because it's the fluence that's important, not the total energy." "The fluence is what drives the process. Fluence is directly responsible for the temperature increase in whatever the target is." "Isn't it cool though what happens in your skin when you shoot a laser in there? Or a light, not just lasers." "If you pre-cool the skin before you fire in your light energy, there's a smaller chance of triggering the pain receptors." ABOUT THE HOSTS Mike began his career in medical lasers in 1986 with a physics degree and a post-grad in bioengineering. He helped develop the scar-free removal of tattoos using a Q-Switched Ruby Laser in Glasgow, and the world's first IPL system. Known well in the industry for his hard truths, no BS attitude and logical answers. As the author of three books, articles for medical journals, a well read blog, a Laser Protection Advisor and contributor to the BMLA, Mike is the Laser Guru. Lisa's claim to laser fame is being Mike's daughter. Growing up with lasers and never avoiding a physics lesson from her Dad, it was natural to enter the industry. Leaving a corporate career with a baby to jump into self employed life came with challenges. Despite that Lisa has been well recognised for her teaching style, practical tips, bringing the compassion to the science, and laser mentoring. Instagram: @dermalase_lasertraining https://mikemurphyblog.com https://www.dermalasetraining.com This Podcast has been brought to you by Disruptive Media. https://disruptivemedia.co.uk/
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