If You Replace the Laser Spot from 1 cm x 1 cm with 1 m x 1 m:What Happens to Energy Density and the Effect on the Body/Hair?

Interesting question! In laser hair removal, the standard "window" (spot) of the handpiece is an area of ~1–2 cm² (1 cm x 1 cm = 1 cm²). If you increase it to 1 m x 1 m (area 10,000 cm²), it's like trying to "epilate" an entire room with one pulse. Let's break it down scientifically (physics + cosmetology), without formulas but with calculations.1. How Does Energy Density (Fluence) Change?Fluence is the energy of the laser pulse per unit area, measured in J/cm². For effective hair removal, you need 20–60 J/cm² — this heats the follicle to 70–100°C without damaging the skin.

With a standard spot (1 cm²), all the pulse energy (say, 30 J) is concentrated in a small area → fluence 30 J/cm².

With a huge spot (10,000 cm²), the same energy spreads over a gigantic area → fluence drops 10,000 times (to 0.003 J/cm²). It's like spreading a spoonful of honey over a football field — density approaches zero.

Result: The laser beam becomes "diluted" — the energy is too weak to heat the melanin in the hair.2. Effect on the Human Body and Hair

On hair: No effect at all. Destroying the follicle requires focused energy — here it's too scattered. The hair won't even warm up, and hair removal won't work. At most — slight warmth, like from the sun.

On skin and body: Minimal. At such low density, the risk of burns/side effects is zero — energy is evenly distributed, like weak infrared light. But there's no benefit either. If the laser is powerful (industrial type), it could cause mild heating of a large area, but for cosmetology, it's useless and dangerous (scattered beam can damage eyes from a distance).

Creative example: Imagine "epilating" a crowd at a concert with one flash — no one would notice except a slight "warming." But for a salon, it's absurd — the procedure would take a second, but with zero results.In reality, such huge spots are not used in cosmetology — the optimal is 1–2 cm² for precision.If you have specific symptoms or a model — write, I'll advise more precisely!Romshi — Manufacturer of 808 nm Diode Stacks
Supplier of Laser Hair Removal Machines & Spare Parts