Hacking a home laser hair removal unit

[Adler]

I have obtained a fancy schmancy home hair removal unit and I'd like some advice on its hackability.

The unit is a "Me My Elos" home laser kit. It comes with a laser cartridge that lasts 5400 shots before its "empty". Obviously this is just a software counter built into the laser cartridge. I'd like to reset it.

I have disassembled the cartridge...




It seems obvious that "U1" is the relevant chip but what is it? it says "2kqc" on it and has 5 leads.

[macboy]

Likely a I2C EEPROM in SOT23-5 package. These are commonly available. Do you have something to read/write I2C EEPROMs? Bus Pirate? Minipro TL866? Etc.
Of course you may need to acquire a new module just to be able to read the contents of the EEPROM from a fresh one so that you know what to program back into the expended one.

[ovnr]

It's almost certainly a I2C EEPROM, something like a 24AA02.

If the device isn't at all clever, you could probably just force the write-protect pin high; that'd prevent it from decrementing or incrementing the counter.

I should point out that the (likely) xenon flashlamp will wear with age, and at end of life it may decide to explode if you continue using it. It may be a bad idea to override it. At least inspect the bulb, and don't go too far.


Do post more pictures of the rest of the unit too. Never knew you could get flashlamp-pumped solid state lasers for home use...

[richard.cs]

Never knew you could get flashlamp-pumped solid state lasers for home use...

It probably isn't. I suspect that the hair removal is just the intense light from the flashlamp and the "laser" bit is just marketing.

I would be inclined to agree that the purpose of the cycle limit is to prevent user injury from exploding lamps, but would still override it anyway and do some tests, and to perhaps see if another cheaper lamp could be substituted.

[IvoS]

But the main action of hair removal is done mechanically by the spinning wheel. The lamp could partially work as antiseptic if UV light emitted.

[Scrts]

If you touched the bulb with the fingers - it will be dead soon. The mud and fat from the fingers covers the bulb and this makes the glass to heat inconsistently.

[Gall]

Hm... it may be a YAG laser, they are relatively cheap. Even a Q-switched one. Like SSY-1 but smaller.

[ovnr]

After some quick looking around, it looks like this is just "intense pulsed light", not an actual laser.

I'm disappointed.


Also, this means I can just go get my Canon 430EX flash strobe in the event I needed to remove some hair. The energy levels are high enough in any event, it melts holes in black trash bags and burnt a pattern into a lenscap I left on top of it...

[mikeselectricstuff]

After some quick looking around, it looks like this is just "intense pulsed light", not an actual laser.

I'm disappointed.


Also, this means I can just go get my Canon 430EX flash strobe in the event I needed to remove some hair. The energy levels are high enough in any event, it melts holes in black trash bags and burnt a pattern into a lenscap I left on top of it...

It may have a special gas mix to optimise the output wavelength, so might be different to a camera flashtube.

[james_s]

Might, but I doubt it. These things are gimmicks for the most part, there's no laser at all, it's just a flash lamp to make it look like it's doing something. You'll get a pulse of intense heat that probably feels similar to the real laser hair removers but I seriously doubt the flashlamp is going to do anything beyond that. People wouldn't pay crazy money for professional services if a cheap off the shelf contraption worked.

[thm_w]

Might, but I doubt it. These things are gimmicks for the most part, there's no laser at all, it's just a flash lamp to make it look like it's doing something. You'll get a pulse of intense heat that probably feels similar to the real laser hair removers but I seriously doubt the flashlamp is going to do anything beyond that. People wouldn't pay crazy money for professional services if a cheap off the shelf contraption worked.

They work but from what I can see, only for those with light skin and dark hair: https://www.amazon.com/Silkn-Flash-Hair-Removal-Device/dp/B00HX27AM4/

The wavelength the Flash & Go uses (475-1200nm) is similar to other Silk'N AND other IPL/HPL products

https://en.wikipedia.org/wiki/Intense_pulsed_light

A 2006 article in the journal "Lasers in Medical Science" compared IPL and both alexandrite and diode lasers. The review found no statistical difference in effectiveness, but a higher incidence of side effects with diode laser treatment. Hair reduction after 6 months was reported as 68.75% for alexandrite lasers, 71.71% for diode lasers, and 66.96% for IPL. Side effects were reported as 9.5% for alexandrite lasers, 28.9% for diode lasers, and 15.3% for IPL. All side effects were found to be temporary and even pigmentation changes returned to normal within 6 months.

[LaserEng]

It's just a IPL system, Intense Pulse Light and certainly not a laser, dodgy marketing there.

The flash lamp is most likely doped with Cerium to keep all most of the UV light inside the lamp or the manufacturer just doesn't bother about giving their customers skin cancer.

From the board it seems that the maker is Syneron Candela which is an Israeli medial laser company.

[Scrts]

Just out of general interest: did anyone ever see a disassembled actual laser hair removal unit? It seems like it's a box on the wheels and must be heavy. Just marketing again? What lasers do they use? What power?

[james_s]

They do make actual laser hair removal units that use a real laser, they are not intended for home use though. They use pulsed lasers, originally ruby, but argon ion and solid state YAG and diode lasers have been used. I don't know what is in the modern units but I suspect they're mostly diode lasers.

[Scrts]

They do make actual laser hair removal units that use a real laser, they are not intended for home use though. They use pulsed lasers, originally ruby, but argon ion and solid state YAG and diode lasers have been used. I don't know what is in the modern units but I suspect they're mostly diode lasers.

It still seems to be crazy big. E.g. the device here: http://www.lumenis.com/Solutions/Aesthetic/LightSheer-INIFINITY

[james_s]

That doesn't look all that large for a piece of medical equipment. The old ruby and gas laser based units were significantly larger. People forget how big and bulky lasers were prior to the diode laser revolution over the last 20 years or so, and even with small diode lasers there is a whole lot of other stuff in there. Optics, computer control, safety systems and interlocks, power supplies, cooling, etc. Medical equipment is a different world.