Mirrors for DT40pro's

[JimBo]

Is that the specs of the DT40pro mirrors or replacement ones?

Jian, can you replace the mirrors if needed?

Jim

edit: the loss on the red could be because the red at the moment has quite a large beam > 5mm.

[steve-o]

What wavelength red are you running Jim?

[Astroguy]

Mirrors High quality medium film 
glass ,reflectivity>95%

This is for the DT40Pro's mirrors.

I cant see any losses on my sets! And I got 3 of them

My first set of DT40`s did not have this problem, the mirrors were fine. But when I got the pro`s I noticed the mirrors were not the same. They must have got some from a different supplier.

[JimBo]

What wavelength red are you running Jim?

650nm.
I am going to use the mounts for the reds for the new diodes in the GB.
I will focus them a bit tighter so hopefully the red will fit on the mirrors.

Jim

[Junktronix]

Yes, the coating on the mirrors is CRAP! Good scanners with BAD mirrors. I get red, green and blue thru my mirrors not much maybe a few mw but that is just not acceptable. The mirrors on my BL30K scanners are great 95% and the scanners are just as good as the DT`s if not better. IMO

Actually, a few milliwatts is normal. If the mirrors are 95% reflective, 5% of your light doesn't get reflected. Put 100mW into the scan set and expect 10mW loss (5% loss at each mirror). Dielectric mirrors are a few percent better reflectivity but are 10X the cost. They are also way tougher so they don't get scratched as easily when you clean them or burn up when you dump 10W into them.

Kevin

[JimBo]

What is the likelyhood of screwing the galvos if you change the mirrors without the special kit?

Jim

[Astroguy]

Actually, a few milliwatts is normal. If the mirrors are 95% reflective, 5% of your light doesn't get reflected. Put 100mW into the scan set and expect 10mW loss (5% loss at each mirror). Dielectric mirrors are a few percent better reflectivity but are 10X the cost. They are also way tougher so they don't get scratched as easily when you clean them or burn up when you dump 10W into them.

Kevin

I did not get any light through my 30K scan set and the first set of DT40`s. the mirrors are also thicker on my 30K set. I tried the mirrors of the 30`s with a green laser and get no light through them, I can see the spot on the other side of the mirror but not enough to even measure. I don`t have my first set of DT40`s any more to check for thickness but I believe they were thicker also.

[yaddatrance]

Also to inject some sanity...

The front surface mirrors that you buy surplus are in a category called enhanced aluminum which provide 99.9% efficiency. To get enhanced aluminum mirrors non-surplus is pretty expensive and the only problem with those (and other aluminum mirrors) is that they ablate at powers >1W... I've completely toasted really nice 1/200 mirrors learning this truth.

From what I can tell, the older DT-40's use aluminum mirrors and have higher reflection but cannot handle >1W lasers. The newer DT-40 pro mirrors, look dielectric to me. I see 95% efficiency which is on par with standard Cambridge dielectric mirrors and I haven't had a problem with cooking the mirror with 5W of power through them...

If you're looking for 99.9% efficiency while preserving the ability to run high power lasers, be prepared to drop $500 per mirror.

YMMV.

[LaserLover]

You must have got lucky or don't have a sensitive enough laser power meter that's wavelength specific.
I measured 10% loss at 457 nM but was so disgusted after that i didn't bother taking readings at other wavelengths. Blue photons are too expensive to waste.

Rick

[steve-o]

Heres some 97% (low power?) mirrors from EO for $17. Could be ground down to spec by a glass shop maybe..
http://www.edmundoptics.com/onlineca...productID=1743