DT30 mirrors - life?

[dnar]

I am noticing the mirrors on my DT30s are leaking somewhat, as if the reflective coating is burning off.Its not a lot, but with the cover off I get beams on the ceiling and I have confirmed they are leakage through the top mirror (Y axis). The leakage is most noticeable with 445nm so I am wondering if the reflective surface is being slowly burnt away from my 1W 445nm. I would have thought these mirrors would cope with much higher powers than I am using.

PS they are the larger mirrors.

Cheers.

[The_Doctor]

Are they aluminised mirrors? If so I think you're right. I can't remember who posted recently about deliberately drawing focussed laser light on a standard mirror to remove the coating, but I think they were talking about visible wavelengths. So if the coating can disappear cleanly and quickly, I'm sure it can disappear cleanly and slowly given enough power even without focus. Multilayer dielectric mirrors for 20W or more exist for scanners, but I bet the cheaper ones don't use them.

[badger1666]

Dt mirrors are shit at 445nm greater than 4w on clean mirrors and you can lose upto 1w due to leakage also at that power they start to burn the coating if not dead clean .
Mine are sealed and fan cooled in order to cope with my 10w+ rgb
I plan on replacing the mirrors with the high power set that one stop laser shop sells
You think that dt might have done something about there mirrors by now 445 been about long enough.

[m0f]

I don't have a problem with 3-4W of 445nm on the newer DT series scanners, so I think they have fixed that. Losses seem relatively low (it's been awhile since I took the measurements, but if memory serves something like 5-7% when new) and with each wavelength performing roughly the same. I do have trouble with wear and tear, likely due to a combination of erosion from dust and from burning of the coating.

I have a set of DT40W, that have been used for about 3 years with ~2.5W RGB and the centre of the mirror where the power was at peak is not eroded to the point that there is a lot of scatter, very noticeable when projecting single beams or hot beam type cues. If I position the beam not centred on the mirror I can still get decent performance, so that shows it's not just dust erosion and likely related to heat from lasers + dust.

I have 2 sets of dt30's running on ~3W RGB for the last 2 years or so and one of the sets is starting to shows the same issue. And finally two sets of DT40pro's running with ~10W of RGB for the last 8 months or so, so far good condition.

I wonder how long a higher quality set from OSLS would last in the same conditions by comparison..

[JD3]

Are they aluminised mirrors? If so I think you're right. I can't remember who posted recently about deliberately drawing focussed laser light on a standard mirror to remove the coating, but I think they were talking about visible wavelengths. So if the coating can disappear cleanly and quickly, I'm sure it can disappear cleanly and slowly given enough power even without focus. Multilayer dielectric mirrors for 20W or more exist for scanners, but I bet the cheaper ones don't use them.

That was me
Was a 1064nm 10watt

[The_Doctor]

That was me
Was a 1064nm 10watt

Thanks. Ok, so not visible then. But given that IR can do this, the odds are that 2W of shortwave light can knock off an atom or two regardless of focus, if strong enough. Whether it needs the reaction of contaminants or will do it anyway I'm not so sure. First thing I decided when I set up my WideMove scanners was to put them in a dustproof chamber. Not a lot of fog ever got in there either. The mirrors are good, but I never used much power on them, not more than 500mW.

[m0f]

One thing I just realized when I said 3 years, I never really specified the type of use. These were used in doing commercial shows, an average of 8-10 hours per weekend. Including many outdoor shows in super dusty environments. So would be a lot difference from 3 years of home use in a clean environment. All in all I can say they don't owe me anything at this point, though it would be nice if they lasted forever