Laser mirrors

[Jerome Stanek]

I saw someone make laser mirrorsout of an old hard drive platter has anyone tried this

[Dave Sheldrake]

Possible and has been done but why anybody would want to apart from proof of concept I'll never understand, Mirrors are cheap compared to the machines they go in.

cheers

Dave

[walter hofmann]

hi there
yes I was the one who started this and published then. it was more out of emergency because the spare mirror broke and the new mirrors did not arrive on time.
but in the mean time there are so many who have replicated this and are used very successful.
I made many comparison even with the most expensive mirrors ( $350) and there is no difference in engraving detail or cutting power, but this mirrors are very scratch resistant even after many cleaning process there is no scratch to discover even under a microscope against the original mirrors who show very fine scratches after three to four times careful wiping.
in the mean time I and many others using them, since over two years and they are free
greetings
waltfl

[Jerome Stanek]

hi there
yes I was the one who started this and published then. it was more out of emergency because the spare mirror broke and the new mirrors did not arrive on time.
but in the mean time there are so many who have replicated this and are used very successful.
I made many comparison even with the most expensive mirrors ( $350) and there is no difference in engraving detail or cutting power, but this mirrors are very scratch resistant even after many cleaning process there is no scratch to discover even under a microscope against the original mirrors who show very fine scratches after three to four times careful wiping.
in the mean time I and many others using them, since over two years and they are free
greetings
waltfl

Thanks for the quick answer I have a bunch of old hard drives and could use some spare mirrors I only have one left as I dropped one and it broke. Just didn't want to order anther set if I don't have to. My mirrors are 20 mm do you use a hole saw to cut them and what size hole saw?

[walter hofmann]

297467I did go to ACE hardware and bought a hole saw what they use for sheet metal with the inside diameter what I needed in your case 20mm .then I covered the whole disc with tape to prevent scratching the surface.
from the hole saw take out the center drill and put it in a drill press and center the disc part and cut it out. instead the red part you can take any plain piece drill a center hole .
greetings
waltfl

[Kev Williams]

Just curious, what are HD platters made of? If a sheet metal hole saw will cut it, what about machining them? I machine lots of aluminum, plastic, brass and thin sheet metal with my larger engravers using collet spindles and regular carbide endmills. I don't NEED any mirrors at the moment, but I have probably a dozen junk HD's around here I can play with!

[Kevin Gregerson]

A quick lookup on the internet says they are aluminium with a platinum alloy coating. Curiously, I'm wondering how much the plantium alloy absorbs co2 energy. As it's reflective is in the lower portion near fiber wavelengths so I could see it working great for fiber. But I'm curious what the energy loss is in comparison to ZnSe in the 10.6 micron wave lengths.

[Dave Sheldrake]

IOR is about 75% Vs 10,600 Kev, they are quite likely to get hot...in some cases VERY hot

cheers

Dave

ps: Lens's are Zinc Selenide, mirrors are usually silicon glass that is PVD plated with gold or are solid copper / molybdenum.

[Kevin Gregerson]

IOR is about 75% Vs 10,600 Kev, they are quite likely to get hot...in some cases VERY hot

cheers

Dave

ps: Lens's are Zinc Selenide, mirrors are usually silicon glass that is PVD plated with gold or are solid copper / molybdenum.

Depends on what it is. The alloy mix is supposed to be about 40% platinum. Whatever the other stuff is might be good enough to keep it from getting hot. Something I'll need to test. I've got a tester here I can use to figure out the differences in power. Just have to cut the mirror out of a hard drive platter.

[walter hofmann]

297573hi all
I am actually not interested in theoretical calculation or to find out what the since values are, but I look for the practical values.
first the power loss can not be seen, the heat is nothing they don't get even warm, no distortion can be seen on the lasered product
here are pictures from the quick comparison
greetings
waltfl

[Kevin Gregerson]

297573hi all
I am actually not interested in theoretical calculation or to find out what the since values are, but I look for the practical values.
first the power loss can not be seen, the heat is nothing they don't get even warm, no distortion can be seen on the lasered product
here are pictures from the quick comparison
greetings
waltfl

It really depends, you may not notice much on a 30 -60 watt range simply because your power loss is only 5-15 percent and most "good" lower wattage tubes are over their standard output by that equivalent. But compound that into a 120 to 180 watt system and you'd likely see more power loss and heat.

For us it's a matter of just seeing the wattage loss difference between stock and the alloy mix. I like the ability to get a mirror that lasts longer and holds up better. But, I'd also like it to reflect a similar wattage to the table or better. My curiousness is more to see if it is actually the same or better and if it's worse, how much.

[Dave Sheldrake]

Like Kev says Walt, 10% loss on a 40 watt won't notice, 10% loss on a 200 will.

Looking at my beam profiler output and the power meter the platter mirrors lose about 22% on my 200 watt as well as going up in temp by 25 degrees leading to a much more noticeable multi-mode beam.

Kev try Moly mirrors, they last a LOT longer, will cope with far higher damage and heat but they do lose just under 1% power (reflective index) compared to Gold PVD.

cheers

Dave