9 replies to this topic

[DrkNite]

I have a <5mw green class III laser pointer mounted on my refractor, and got curious as to how the the Seestar solar filter would work against it. Well, I found out.

 

Don't do it, it will trash the filter.  

 

I have other solar filter material to use as a replacement in the holder, so no big loss. The result was interesting, and I didn't expect it.  The replacement material I have isn't suitable for visual use but works for photographic use.  It is thicker than the Seestar filter material.  As a comparison, I did the same "test" with a scrap piece of the material and it did not have the same result.

 

Here are 2 pics from the "experiment".  One shows the filter as a whole, and the other is a close up of one of the areas that was subjected to the laser.

 

 

 

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[TOMDEY]

Interesting experiment! The rule is to never point a naked (unexpanded) laser at a filter that operates on the principle of absorption. All dielectric filters (i.e. non-absorbing) probably OK. I worked vacuum coatings for decades and we would always chuckle when we came across damage as you show there and then ask around, "Who's the new technician?" The biggest danger is infrared or UV lasers --- you can blow your eyes out (or start a fire) without even knowing you're doing it --- until its too late. How do I know this? --- yep --- it happens. One curtain in one of our labs ignited, and (another incident) one guy permanently blinded (in one eye). Neither of these were me. But I do take credit for coming this >||< close to torching an entire giant building --- only very quick thinking and luck defused that stupidity.    Tom

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[Don W]

I only have one question, WHY??

[Jim Waters]

I find it hard to believe a 5mw laser can do this.

[Marcus1]

That looks just like a STOP sign I passed on the road today.

[DrkNite]

I only have one question, WHY??

Why not? I had planned on replacing the filter anyway, and was curious.

I certainly didn't expect it to make actual holes in it. That aspect was interesting as well. The filter initially reflected the beam as I was expecting, then the beam pattern on the reflection changed after a second or two. I thought I had moved the filter to one of the areas that was wrinkled (hence my wanting to replace it), and tried at a different area. It did the same thing and that's when I discovered the holes.

[DrkNite]

I find it hard to believe a 5mw laser can do this.

 

I didn't think it was possible, but here it is.  The laser actually says "<5mW" on the label.

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[DrkNite]

Interesting experiment! The rule is to never point a naked (unexpanded) laser at a filter that operates on the principle of absorption. All dielectric filters (i.e. non-absorbing) probably OK. I worked vacuum coatings for decades and we would always chuckle when we came across damage as you show there and then ask around, "Who's the new technician?" The biggest danger is infrared or UV lasers --- you can blow your eyes out (or start a fire) without even knowing you're doing it --- until its too late. How do I know this? --- yep --- it happens. One curtain in one of our labs ignited, and (another incident) one guy permanently blinded (in one eye). Neither of these were me. But I do take credit for coming this >||< close to torching an entire giant building --- only very quick thinking and luck defused that stupidity.    Tom

 

Interesting!  I got a chuckle out of the laser defender curtains.  How do those work against the UV or IR lasers, and what kind of power can they handle?

[DrkNite]

That looks just like a STOP sign I passed on the road today.

 

Hmmm, maybe I should paint it red. 

[TOMDEY]

I find it hard to believe a 5mw laser can do this.

5mw intentionally contact-dwelled on a tiny spot on a very thin thin black material --- ideal condition to induce localized temperature spike. You can run the number where the beam diameter at the laser is  approx = 2 x wavelength / divergence. It comes out to a very small spot there and therefore a very high power density input (to that tiny spot) of the thin material.    Tom