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ArcticMyst Security by Avery

Looking at a 1-1.5 W 445

2100

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Yea, I think what I learnt in CPF is that for every doubling of distance, the power drops by a factor of 4 approx. Say for 8mW at 6 inches, that'd be 2mW at 12 inches, 0.5mW at 24 inches. Our 0.39cm^2 pupils are 6X bigger than 15mm x 15mm, so we'll take it as 0.08mW.

Can InfinitusEquitas measure the reflective power from say a glossy laminate, or say the refrigerator, glossy acrylic cabinets? Polished Marble/Granite slabs (kitchen tops), or semi-glossy homogeneous floor tiles? Transparent windows reflect a lot back as well. Anodized aluminum say from cooker gas hob? I have all those in my house.

Even a harmless plastic AC switch/socket might reflect quite a lot. Or from the airconditioner's ABS plastic. In effect if you really wanna be safe in the house, the laser needs to be "static". ie as what i've said earlier : don't wave it around in the house without glasses. :D

The pupil size vs LPM sensor size is definitely valid. But not sure if the pupil size really constricts as much. Coz my experience is that having a 1W laser focused perfectly to an optimal spot does not constrict the pupil much as compared to say a 10W XM-L LED with relatively much much bigger hotspot. I mean you do not lose your low-light vision as much. (because i play with my stuff often at night, always look out to look at the buildings etc. :D ).

I read through the wikipedia article. Regarding the MPE or Maximum Permissible Exposure, there is another graph which I do not understand.

300px-IEC60825_MPE_J_s.png


Anyway this warning in the article sums it best.

- Watches and other jewelry that might enter the optical plane should not be allowed in the laboratory. All non-optical objects that are close to the optical plane should have a matte finish in order to prevent specular reflections.
A girl's polished/manicured nails, or false nails with crystals on it, may be the last things that particular eye ever see.
 
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The styrofoam I was using is actually quite a bit more glossy/reflective than basically everything you mentioned (maybe not well polished white marble). I selected it specifically to represent the worst case scenario...

Also I think you're a tad off about the size of out pupil...

As for warnings... just use common sense... if you're gonna go around your house swinging the laser around, wear goggles. If you're mindful of where you point the beam, you should be fine. Personally, aside from mirrors, my biggest concern is with my glossy monitors and tv screens. I'm not gonna shine a 1W laser at them though... if one breaks down I may, but for now I'm not willing to try that experiment.
 

2100

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The styrofoam I was using is actually quite a bit more glossy/reflective than basically everything you mentioned (maybe not well polished white marble). I selected it specifically to represent the worst case scenario...

Also I think you're a tad off about the size of out pupil...

As for warnings... just use common sense... if you're gonna go around your house swinging the laser around, wear goggles. If you're mindful of where you point the beam, you should be fine. Personally, aside from mirrors, my biggest concern is with my glossy monitors and tv screens. I'm not gonna shine a 1W laser at them though... if one breaks down I may, but for now I'm not willing to try that experiment.

Sorry, I mean to say our 0.39^2 pupils are 6X smaller than 1.5cm x 1.5cm LPM sensor. But the power calculations are correct, as i divided LPM power readings by 6.
But then that kind of calculation is for incoherent light though. For spatially coherent light on some degree or % of glossy materially, that rule goes out the door.


Just took some pictures. I mentioned refrigerator, here's the pic of 445nm vs Dereelight XR-E R2 aspheric. Reflective surface to wall is 3 metres. XR-E aspheric is about 12 inches.
original.jpg



Also mentioned glass (not mirror), this is much worse! 445 vs Dereelight XR-E R2 aspheric. XR-E aspheric is 12 inches also. Glass to wall is 4 metres.
original.jpg


For longer distances, we all know that 405/532s hold their beams much tighter.
For glossy surfaces its quite scary huh...... :cryyy:

Just for info the Dereelight XR-E aspheric (my XR-E R2 light tailcap is measured at 1.2A) "throws" better than my ~ 800 lumens XM-L (2.6A tailcap).

I think for plasmas and glossy LED screens, it'd be quite close to the refrigerator. I have 3 screens available for testing but like you, none are destined for the trash. :D

But you are right, common sense is very important. Laser on absolutely non glossy surface is good for the record.
 
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I'm glad to see this information is progressing. But yes, I would also like to see it on glossy granite, semi-reflective glass and a refrigerator, just to show people just how wrong they are :p
 
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I'll do a test for glass and a refrigerator tonight... I'm actually quite curious how much a regular piece of glass blocks, and how much is passed through.

Now as for granite... hmm, gonna need to think about that I don't really have any on hand:D

@2100 One important detail to note... just because we can't see the light, doesn't mean it's not there. I mean all my flashlights light up a room a lot better than lasers, but consider that we're dealing with totally different wavelengths. So for the purposes of safety I would completely disregard appearance.
 

2100

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I'll do a test for glass and a refrigerator tonight...

@2100 One important detail to note... just because we can't see the light, doesn't mean it's not there. I mean all my flashlights light up a room a lot better than lasers, but consider that we're dealing with totally different wavelengths. So for the purposes of safety I would completely disregard appearance.

My refrigerator is a Mitsubishi with silver white glossy surface, so it might be quite reflective. Other models probably less so. I find anodized silver to be pretty diffused because the surface is non-glossy.

I think its actually not easy to LPM the spot, taking pictures is quite challenging esp with safety glasses on top of my prescription glasses. I tried it on my Sharp KC-840E air cleaner, I need to defocus it first so as not to burn the plastic… LOL! Its quite reflective, and I think similar would be so for any glossy plastic like those on LCDs/vacuum cleaners etc.

This is on my black granite with white streaks (forgot the name but its sealed and polished, so its glossy). Volokas marble also shows similar hotspot. My "man-made" compressed marble chips dining table is not as polished so the reflection is not as bad. This is the brightest, ignoring those mirroed surfaces like kettle or glass.
http://74.84.129.4/dynamic/product_images/bc-small/95472/744032.jpg

medium.jpg


My Black Galaxy granite is somewhat lower in intensity. My homogeneous floor tiles and toilet ceramics are also lower in intensity, but still quite bright.
But as a gauge it is not as bright as my 6” reflectored 75W HID's hotspot just a few feet away. (seriously the HIDs are definitely more than enough to blind anyway)

Yeah i know flashlights light up the room better. But it is the only gauge I can do visually, just a gauge on the different hotspot intensity.
 
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@2100

I think you need an LPM:D

It's actually very interesting, but my brightest laser 400mW 532nm o-like is only one third as powerful as my best 445nm... When dealing with lasers, looks ARE very deceiving. For a laser to laser comparison burn tests would actually indicate power a little better, but there is a huge amount of error with that approach as well.
 

2100

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What I need is a lux meter. :san: I am more into the flashlight hobby. Lasers is for burning, kick of cutting a visible throw the air and throwing light onto distant objects. "Pocket rocket".

If you are talking about power....yeah 532 would do a dot that's much brighter visually. There's a calculator link that's being posted for visibility between the WL in terms of beam visiblity and dot visiblity, the numbers are crazy, but there are arguments on its accuracy.

For cameras using the Bayer filter and CCD combi, it has twice as many green sensors compare to red and blue. This is to mimic how the eyes perceives colour (out eyes are more sensitive to green). Eg, if R G B sensors are the same in the cam, the net effect is "flat", but our eyes will see a wierd image.

Same for music/sound, equal loudness curve. Ears most sensitive to midrange at about 3kHz I think. We don't hear low freqs well.

So in reality, our 445nm packs more power/damage than the LED. 405nm is worse.
In my pix the LED is already quite dimmed anyway....the 445 really packs a punch on glossy.
 
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even the best laser safty glasses are under 100$ ,,,i have yet to see a new eye that cost under 100$ very easy to get safty glasses very hard to get new eyes
 
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Lee7

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Thanks for doing those experiments, Infinitus! Its interesting to think about these things, but seeing as I don't have a laserbee it was more or less academic. I'm glad you found this thread and actually tested out the different objects, keep up the good work!
 
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