Custom Effects Lenses or No?

[BERFIN]

I don't think so, the light passes through the diffraction gratings and isn't absorbed by it. Seriously, shine your 445 through clear plastic and see if it burns. Even if focused to a very small point on the plastic it wouldn't burn.

Also if the diffraction grating was absorbing enough light to get burnt you wouldn't just smell it, you would obviously be able to see the damage. The smell was probably your arctic getting fried.

I used the SAME EXACT star caps that are in the pic at the top. And my 1100mw 445 build melted the crap out of it. I guarantee it will melt it.
(not instantly but with in 30secs after being turned on it will start)

 

[benmwv]

Trevor, you have it exactly right.

Eudaimonium:
The lenses do have 20-30% of power loss, but we are talking about absorption only and not reflection. I saw a thread a while back where a member measured reflections off of glass and, depending on wavelength and varying pieces of glass, had 12-15% reflection IIRC. (but I guess these weren't ar coated) Also collimating lenses have multiple optics inside them, accounting for even more loss.

Really the main point I have to make is that just because you can manage to burn through plexi or thin plastic doesn't matter because that is when focused to the smallest point possible. A diffraction grating would sit right at the aperture, with the beam hitting a spot ~.75cm squared on it.

Also I would be very interested to see if you are able to burn through the plexi glass

 

[Trevor]

Really the main point I have to make is that just because you can manage to burn through plexi or thin plastic doesn't matter because that is when focused to the smallest point possible. A diffraction grating would sit right at the aperture, with the beam hitting a spot ~.75cm squared on it.

If a speck of dust lands on the spot where the laser is passing through, it will start to heat. If it remains there too long, it will transfer heat to the grating, which will begin to discolor. See previous explanation.

Also, the grating is absorbing some power. So, even focused to infinity the grating will eventually wear out. The speed of this is determined by factors such as the makeup of the grating, the wavelength of the laser, impurities on the surface of the grating, etc.

It would be an awful waste to burn a hole in a diffraction grating to prove this can happen...

-Trevor

 

[extremeodd]

Ive used my diffraction grating caps (5 in 1!!!1!!) with my 1w 445 quite a few times, never had a problem with melting but I didnt use them for more than 45s or so. Kinda a pain to get everything in position but Ive found if you get a cheap greenie with the caps you can yank the tip of it off that holds the caps and that fits almost snugly on a stock aixiz focus ring. 445s make for lousy effects due to the rectangle dot, but still looks awesome none the less.

 

[Kansas Outcast]

heres a link that I was just provided for glass diff grating
DEOS Silicon Diffraction Grating Mirror CO2 - eBay (item 390016805648 end time Apr-01-11 18:29:04 PDT)