Just received my O-Like 808nm 200mW (?) "burning" (?) laser

[zyxwv99]

17 days ago I ordered a 200mW 808nm laser from O-Like. (High Power Infrared 808nm 200mW laser pen /burning [OL-H808-200] - $36.99 : Zen Cart!, The Art of E-commerce)

It arrived today. I put in two AAA batteries, Walgreens generic alkaline. (The ad says 2xAAA) The second battery doesn't quite fit into the little sleeve in the tail cap, so I put aluminum foil in there to make the connection. Otherwise you have to force the battery in so that the outside of the battery scrapes off.

The first issue is it doesn't look very bright. So far so good. 808nm is infrared. It's supposed to look dim.

The second issue: I can't feel any heat, even when holding it 4 inches from my hand for 10 seconds.

At 4 inches the beam focuses to a square about 1/16 inch across, or about 1.5 mm. Any closer and it becomes a vertical bar, any farther and it becomes a horizontal bar.

I do not have a Laser Power Meter.

Shouldn't a 200mW "burning" laser generate some sort of heat? Am I doing something wrong? :can:

 

[Speedy78]

Do you have glasses rated for IR light at 808?

Without a LPM it will be hard to tell its output. I would start with appropriate safety glasses before you do any more focusing.

 

[zyxwv99]

No, I don't. Somehow I get the feeling that laser safety glasses come in four strengths:

1) $8-12 eBay strength
2) $25-$40 strength
3) $125-$250 strength
4) $$$$$ professional grade

What price level do your recommend? (By the way, I need to log off now until tomorrow morning.)

 

[Speedy78]

I reccomend eagle pair. They run around 40-60$ Look at the specs and get something at least OD2 for that laser. Though I reccommend you get the highest you can afford. What is your reasoning for the IR? Alot of people seem to be getting them latley and I'm just curious.

 

[zyxwv99]

I found some information about what the OD numbers mean. Even though the Wikipedia has an article on "Laser protection eyewear," it contains almost no information. However, the related article "Laser safety" has something, including explaining OD numbers and how to determine what kind you need.

As for my interest in IR, I can't speak for others but I'm interested in human color vision for a number of reasons. I have worked in graphic design and continue to do some work in that area. That means knowing more than just basic color theory. For example, if a printed page doesn't quite match what's on the computer screen, I need to worry about things like the optical properties of the paper and metamerism (e.g., white paper looking off-white under different lighting conditions).

On top of the that, I have an amateur interest in diamonds, related to an amateur interest in geology. About 98% of diamonds belong to the "cape series" and have a distinctive set of absorption bands, most notably the N3 band at 415.2nm and N2 at 477.6nm. The gives diamonds a perceived hue of the complimentary colors of those those wavelengths, making the diamond look yellowish or off-color.

Unfortunately standard color theory does a very poor jobs of explaining any of these effects. That's why TAPPI (paper industry association) has commissioned studies to find out what's wrong with CIE1931 (color model) and why it doesn't work. There are quite a few diamond hobbyists, some of them with access to expensive laboratory equipment, trying to figure out why color grading and fluorescence grading of diamonds is such a mess.

Compared with them, I'm a newbie. I'm just exploring the edges of the visible spectrum (including trying to find out where the edges are really are). I would like to be able to do so in natural outdoor light, or at least twilight, since colors at the edge of the spectrum tend to be seen only out of context in dark rooms.

You might want to see my thread, "What is the longest wavelength of laser light you have seen?"

 

[Photonz]

OD is optical density and OD+4 reduces the laser intensity by a factor of 10^4 or 10,000 so a 1000mW is reduced to .1mW

 

[zyxwv99]

Last night I figured out how to get the laser to burn things. The tightest focus is at about 6 inches, at which point the dot is a very thin line. In less than half a second it will make smoke come up from many sorts of black plastic and leather. It can't light a match, and I can't feel any warmth (although it look like human flesh is translucent to 808nm so you don't get a sharp focal plane). Newsprint with large areas of solid black ink will not only smoke but burn with a tiny flame, but only as long as the laser is shining on it.

So I'm wondering, any guesses on how many mW of output I'm getting? I'm pretty sure it's nowhere near the advertized 200mW. I think even 100mW should do more than this. I'm just looking for a close-order-of-magnitude guess. 50mW? 25mW? 12.5mW?

Tomorrow I'm going to try Duracell instead of the cheap generic Walgreens I have now.

Even though I bought this laser not to light fires and impress my friends but to see what 808nm looks like, I would like to be able to see that wavelength in the widest possible range of environments and lighting conditions.

 

[Speedy78]

I would say its probably around 100mW. But its hard to tell without a meter.

 

[zyxwv99]

Thanks! That's encouraging. :yh:

 

[zyxwv99]

Unscrewing the cap in the back, taking out the batteries, and looking inside, I see what looks like the driver (black thing with battery-spring facing me, switch on the side). It doesn't look straight. The front end seems centered with the laser module, but the back end (with the spring sticking out) is up against the housing so that the whole thing is crooked. Is there supposed to be a ring around the driver to keep it centered?

 

[Leodahsan]

You can't feel any heat because human skins diffuses the light to the inside pretty well...
My 100mW PHR burns my hand (today it happened by accident )... But a red never burn't me.

Yeah the driver should have some kind of foam around so it don't crook inside the host.
Do you think it happened because of the button??

 

[Laik]

Please don't use this laser anymore until you get safety glasses!