How it works
The flashlamp emits broadband light. Filters pass only the band an indication needs: 610-1200nm for follicle melanin, 530-1200nm for rejuvenation, 585-1200nm for vessels, where oxyhaemoglobin absorbs. Dual filtration blocks everything under 400nm, so no UV reaches skin. Pulses run 0.1 to 10.0ms and split into sub-pulses, delays out to 20ms, keeping the epidermis off the boil. That's selective photothermolysis, Anderson and Parrish, 1983.
RF works differently. Current flows between the electrodes at 2.64MHz, up to 120W, for 0.1 to 3.0s. Heating tracks current, contact area and impedance: our figures put skin near 289 ohms, fat 2180. The archive's dermal band is 45 to 60°C, where collagen remodels. Contact decides everything: 2mm of gel, never reused, the tip always moving, two test shots after any parameter change. A parked tip burns people.
What does the RF add when melanin contrast is thin? Not a second target. Current follows impedance, not colour, so it warms the dermis of a Fitzpatrick type IV. Warm tissue needs less light for the same endpoint, and our pigment tables read that way: 40-48J/cm² at type I, 35-44J/cm² at type III, the RF setting barely moving. StatPearls reports adverse events climbing with fluence and skin darkness. Sadick's 2005 paper called that trade selective radiophotothermolysis. RF can't invent contrast: blonde, grey and red hair barely absorb, and our archive is blunt that IPL isn't effective there.
Where does a single-wavelength laser win? Coarse hair at volume, where an 808nm diode outruns a filtered flashlamp; that's our DL-07 diode platform. Very dark skin, where weak melanin absorption at 1064nm is the point. Tattoo ink needs nanosecond pulses no flashlamp makes: QE-01 territory.