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Confirmed cheap multi-line 980nm/490nm pen

Atomicrox

Atomicrox

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Re: Possible cheap 2-line 980nm/490nm pen

Goggles could work if they are at least OD3 for 980nm, but you ABSOLUTELY NEED a good LPM (one that can detect <1mW lasers) to be sure it's <1mW with the goggles.

Don't ever try this without LPMing the EXACT same setup (laser+filter/goggles) you're going to use. And be sure your LPM is properly zeroed and test conditions are appropriate - at these power levels even your body heat will influence the LPM readings.


Edit: I got the filter I used from a camera, it was attached on top of the CMOS sensor. But not all cameras are created equal, some IR filters are very crappy (the O-like ones come to mind).
 
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rhd

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Re: Possible cheap 2-line 980nm/490nm pen

Absolutely no visible light within the range of my spectrometer (~422 to 665)
 
Atomicrox

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Re: Possible cheap 2-line 980nm/490nm pen

That's a pity. Did you attempt to measure by pointing the laser directly at the spectroscope? The power might be too low to capture from a diffuse reflection.
 
rhd

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Re: Possible cheap 2-line 980nm/490nm pen

Atomicrox said:
That's a pity. Did you attempt to measure by pointing the laser directly at the spectroscope? The power might be too low to capture from a diffuse reflection.
Click to expand...

Sure did.
 
Atomicrox

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Re: Possible cheap 2-line 980nm/490nm pen

The Chinese never learn to install IR filters on these things, LOL.
 
T

trencheel303

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Re: Possible cheap 2-line 980nm/490nm pen

maybe it's not emitting 490nm because you need to put the batteries in backwards?

Also the IR on that thing will be deadly, incinerating your own eyes and the eyes of those in the vicinity. Please purchase OD50 safety goggles.
 
bloompyle

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Re: Possible cheap 2-line 980nm/490nm pen

trencheel303 said:
maybe it's not emitting 490nm because you need to put the batteries in backwards?

Also the IR on that thing will be deadly, incinerating your own eyes and the eyes of those in the vicinity. Please purchase OD50 safety goggles.
Click to expand...

Is that some kind of joke?
 
zyxwv99

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Re: Possible cheap 2-line 980nm/490nm pen

rhd said:
Absolutely no visible light within the range of my spectrometer (~422 to 665)
Click to expand...

According to my calculations, the output of the 490nm should be about 80 picowatts. It looks brighter than the 980nm, but is in the same range. The higher brightness could be accounted for by the tighter beam, so actual brightness would be very close. The sensitivity of the human eye for photopic (daytime color) vision is about 9 orders of magnitude greater at 490nm than at 980nm. If they both look about as bright, the 980nm must be about a (US not UK) billion times as intense. 80mW divided by a billion is 80 picowatts.

Can your machine go down that far?

By the way, people with dark-adapted eyes can perceive fully saturated color in the femtowatt range.
 
The_LED_Museum

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Re: Possible cheap 2-line 980nm/490nm pen

I just purchased one; when I receive it, I'll perform spectroscopy of it and see if I can detect the suspected 490nm laser line.
 
Blarg King

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Re: Possible cheap 2-line 980nm/490nm pen

Interesting. I got my ebay IR pen today, and I haven't tried looking for the cyan color yet since I don't have my IR glasses yet, but I aimed it at some glow in the dark putty, and theres a tiny dot of fluorescence on the putty where the beam would be hitting it. Its super weak, but could that be an indicator that there is indeed a second line emitting from these in a wavelength short enough to cause fluorescence?
 
Atomicrox

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Re: Possible cheap 2-line 980nm/490nm pen

The_LED_Museum said:
I just purchased one; when I receive it, I'll perform spectroscopy of it and see if I can detect the suspected 490nm laser line.
Click to expand...

Cool, let us know!

Blarg King said:
Interesting. I got my ebay IR pen today, and I haven't tried looking for the cyan color yet since I don't have my IR glasses yet, but I aimed it at some glow in the dark putty, and theres a tiny dot of fluorescence on the putty where the beam would be hitting it. Its super weak, but could that be an indicator that there is indeed a second line emitting from these in a wavelength short enough to cause fluorescence?
Click to expand...

I don't think the second line would be strong enough to fluoresce anything, but I haven't tested.

Some materials are fluorescent under IR. It's rare but exists, that's how those IR detector cards work.

Maybe you're seeing the second line itself...
 
Blarg King

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Re: Possible cheap 2-line 980nm/490nm pen

Well its just that the effect occurs on every glow in the dark material I have. I don't think I'm seeing the second line, because its definitely the classic glow in the dark green color I'm seeing.

I think it could be fluorescing. Its really weak fluorescence, like you have to be in a pitch black room and really look for it, but its definitely there.
 
Atomicrox

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Re: Possible cheap 2-line 980nm/490nm pen

Let me try with mine and I'll report back later.
 
Atomicrox

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Re: Possible cheap 2-line 980nm/490nm pen

You're right, it fluoresces GITD stuff. Not by much, but it does. The fluorescence is caused by the IR, not the second line (I tested with and without an IR filter).

FWIW 808nm and 780nm both cause the same effect (fluorescence). As far as second lines are concerned, I couldn't see them on 808nm/780nm lasers, but I only attempted with a camera and it still picks some IR even with the IR filter.
 
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