Balloon popping - power needed ?

[flogged]

Huh, I just discovered that my homemade 635nm pointer
will pop unsharpied blue balloons out to at least two
feet. It takes a while though, close to minute at two feet.
It's interesting as you can see patterns in the reflected
light as the rubber slowly melts prior to popping.

I'm using one of those Meredith brass lens assemblies
that can be focused. The focus is critical. I'm surprised
it's able to pop them.

Any idea if there's a way to figure what the power level
of the laser is? I don't have a laser power meter so I've
often wondered. I'm guessing it's in the 20-30 mW range.

Weeee.

 

[RobTheVIP]

Hmm yeah that sounds about right. I would guess 25 mW, but try using a sharpy on the balloon next time!

 

[Gazoo]

flogged,
Did you get the Meredith with the glass lens, or acrylic lens? I have found the plastic lens that comes with the small aixiz modules to be much better for burning.

 

[flogged]

I'm using the one with the glass lens. Does the plastic lens allow of tighter focus? The next batch I order will plastic lenses if so.

I like the Meredith stuff, it's just a little pricey.

 

[Gazoo]

If you compare the specs on the Meredith website, you will find their acrylic lens provides a smaller beam diameter. I wish I would have before I ordered the one with the glass lens. I have not tried the Meredith acrylic lens, but next time I order from them I am going to give it a try and also order the little heat sink blocks for my next TEC project.

The Aixiz plastic lens kick butt for burning compared to the Meredith glass lens, and they also fit perfectly in the Meredith module. However, the Meredith glass lens produces what seems like a bit brighter and more impressive beam, probably because the beam is larger in diameter.

 

[pseudonomen137]

The only way to test power is to test it on a power meter really. For accuracy, I would suggest a thermal meter if possible as "635nm diodes" normally have a bit of leniency in the center wavelength, and you don't know exactly what wavelength to calibrate a silicon sensor to.

As for balloon popping power, a more important factor is irradiance - the power per area or power density (IE, mW/mm^2). Unaided, I've taken out black balloons with as low as ~25mW of CNI black/gold. Aided, the lowest I've tried is when I popped some black balloons with my 17mW RPL blue. I've even heard of people popping balloons with focused 5mWs before (though I haven't seen proof yet!), so power alone isn't too great of an indicator.

 

[flogged]

If you compare the specs on the Meredith website, you will find their acrylic lens provides a smaller beam diameter. I wish I would have before I ordered the one with the glass lens. I have not tried the Meredith acrylic lens, but next time I order from them I am going to give it a try and also order the little heat sink blocks for my next TEC project.

Yeah I ordered the aluminum mounting block to use a heatsink with the diode lens assembly. It was only an extra $5.00. Works well, takes over 15 minutes before the housing starts to get a little warm. However the diode is only consuming about ~100mA so it really doesn't need much in the way of a heatsink,

 

[flogged]

The only way to test power is to test it on a power meter really. For accuracy, I would suggest a thermal meter if possible as "635nm diodes" normally have a bit of leniency in the center wavelength, and you don't know exactly what wavelength to calibrate a silicon sensor to.

What's the cheapest thermal power meter available? Easy to DIY?

I got these diodes from Kevin C. and he measured the IOP for each diode to lase at spec power (15 mW). The particular diode I'm using was specced at ~70mA, however I'm driving it at > 100mA - so depending on the slope it may be over 25mW. He also had access to the wavelength (which varies from diode to diode) and I think this one tested at ~631nm - one of the few below 635 nm at room temp. It's pretty orange. Be nice to have a connection with a diode manufacturer to get access to the few freak diodes that lase at < 630 nm at room temp. They probably all get cherry picked, who knows.

 

[pseudonomen137]

Unfortunately power meters are expensive any way you look at it, and its not something you can really DIY. My thermal meter setup cost $2,100, and its a lower-end setup. If you really want to know output, you may want to see if some place local like a university could test it for you. If you don't mind paying 2 way shipping and a little wait time, there are also a few people here (myself included) who will be willing to test out your laser for you.

 

[Gazoo]

The only way to test power is to test it on a power meter really. For accuracy, I would suggest a thermal meter if possible as "635nm diodes" normally have a bit of leniency in the center wavelength, and you don't know exactly what wavelength to calibrate a silicon sensor to.

As I recall someone said the difference in power % when testing 650 vs. 660nm, for example, using a LPM-1 would only be a few %. The LPM-1 comes configured to measure 633 and 660nm. So how accurate do you think the LMP-1 would be measuring a 650nm diode?

 

[pseudonomen137]

I know on the lasercheck the transition from 650nm to 660nm made some difference. Its not huge, but its huge enough to put a seemingly in-spec laser out of spec. I just tested a red I have on the LC and got ~115mW at 650nm and ~87mW at 660nm. If you're just trying to get a general idea of what power you're putting out, that's good enough, but unless you have an optical spectrum analyzer, I wouldn't be too confident with measuring a red on a silicon sensor.

 

[Gazoo]

Hmmm, that is quite a difference. Another problem is considering diodes we can't find specs for, such as the open can diode. I do have a feeling however it is a 660nm diode, or very close like the diodes we got from the GB. I don't notice any difference in color or brightness with the open can when comparing it to the sony diode from the GB, and I did power each with the same amount of current.

I do thank you for taking the time to do the comparison. It puts things into a better perspective. Fortunately the LPM-1 can be reprogrammed and calibrated to accept different wave lengths if we run into a situation that calls for it. I really like the plotting capability of the LMP-1 which is the main reason I didn't go with the die4thing meter.

 

[Daedal]

I know on the lasercheck the transition from 650nm to 660nm made some difference. Its not huge, but its huge enough to put a seemingly in-spec laser out of spec. I just tested a red I have on the LC and got ~115mW at 650nm and ~87mW at 660nm. If you're just trying to get a general idea of what power you're putting out, that's good enough, but unless you have an optical spectrum analyzer, I wouldn't be too confident with measuring a red on a silicon sensor.

Pseudo, if it's not much of a problem, could you test that again with the LC at the above wavelengths and then compare it to the thermal sensor you have? I know you use that to create a bit of a spectrum analyser (which is incredible! especially given the price range for one of these) but I'd like to see how they compare

Thanx;
DDL

 

[pseudonomen137]

Pseudo, if it's not much of a problem, could you test that again with the LC at the above wavelengths and then compare it to the thermal sensor you have? I know you use that to create a bit of a spectrum analyser (which is incredible! especially given the price range for one of these) but I'd like to see how they compare

Thanx;
DDL

Sure thing. The laser in question is a glowtorch-style red (sold by Spymode as a 300mW [figures, eh?]). I just replaced the batts and here are the results:
Lasercheck @ 660nm: ~86mW
Lasercheck @ 650nm: ~112mW
Thermal: ~92mW

So the actual wavelength is probably right around 658nm - the spec of a DVD diode.

 

[Daedal]

Nice

Thanx for that Pseudo

--DDL