Monster Hollowing Rig Laser Question ??

[Dan Mosley]

I started looking around for a place to get a couple of new lasers from - Amazon has a few vendors listed and I was wondering what the difference is in them or if anyone uses something better ?

Below is the name of the one that I have bought in the past: this one fits in the holding hole in the arm perfectly so i assume 8mm is the exact fit and length does not matter
RED Laser Module 8mm X 25mm - 650nm 3 Volt <1mW
The above runs in the $35.00 range each

Then I see these other 2 listed as well -
RED Laser Module 8mm X 25mm - 650nm 3 volt
RED Laser Module 8mm X 25mm- 635nm 5 Volt <5mW
These run in the $7.00 range

Im not sure on why the price difference for a brighter light - wouldnt the 5mw be brighter and better ? I have a voltage transformer hooked up from a power cord to reduce it down -
It says 3-12 V - 1.A on the transformer and has worked well in the past so I assume it will work on the 5 volt lasers unless the 1.A limits it...not sure ?

Any thoughts on which would be better to buy ?....................or other vendors and what are others using in their Monster Hollowing rigs ????

From another site my understanding now is that the nm defines the color with Red in the 630-680 range - 1mw would be less bright then the 5 mw but the prices are all over - any ideas on why ?

I know Ebay has them in bulk but not sure about the quality or brightness etc............ anybody shed some light on the specs or suggestions ??

Thanks Dan

 

[Dave Mueller]

Dan,
I have a Monster rig with a laser module that looks like yours. The replacement laser that I have used is http://www.aixiz.com/store/product_info.php/products_id/296 It has a focussing ring that allows you to focus the laser at the correct distance. The ring is a little loose, but can be held in place with one layer of teflon tape from the plumbing section at Lowes. Just be sure to protect the wires where they come out of the laser...they are a little delicate at that point.

I also use a batterty pack http://www.batteryspace.com/batteryholder2xaacoveredbatteryholderwithon-offswitch-rohscompliant.aspx instead of a power supply. This one also has a built-in switch that is very handy.

Let me know if you have any questions.
Dave

 

[Bill Boehme]

The thing to be concerned about is retinal damage from beam power density greater than 2.5 mW/cm² at the wavelength of red lasers, (i.e., centered about 650 nanometers). The thing that concerns me is that some of the focusing systems used with lasers on hollowing rigs may be after-market add-ons that are not authorized or certified to meet the stated ANSI standard by the laser manufacturer once it has been modified with a focusing lens to concentrate the beam.

A power level below one milliwatt (class 1 under the new system) is bright enough at the short distances used for your intended purpose and much safer than a 5 mW (class IIIa, old classification system or class 3R, new classification system). Although that classification of lasers is commonly used as pointers, there are cautions and/or warnings regarding their use depending on configuration. There is a finite risk of retinal damage due to specular reflections when using them around bright metal and other glossy surfaces. Risk is especially of concern when combined with optical systems to focus the beam. The good news is that if you use a class 1 laser, there is no risk of retinal damage even when used with optical focusing systems.

Since I worked in a lab using high powered lasers, I had to be well versed in safety as it related to all classifications of lasers in an industrial environment. While these small lasers are are pretty tame in comparison to the big ones, you still probably do not wish to have a few "holes" in your vision.

 

[Dan Mosley]

Bill - I agree - the one that came with the hollowing rig to begin with is the 8mm X 25mm - 650nm 3 Volt <1mW, which is fine for what im using it for on both my hollowing rigs. The information you posted is interesting and hopefully others will read it also. I have used this same laser module on both my Monster rig and my home made larger one.

Dave's links are for the ones I mentioned so those are the ones ill buy. As for the battery boxes I did order a few to have around but I perfer the transformer hook up.

Thanks Dan

 

[Bill Boehme]

Normally, the laser diode should last a very long time. If you have had them fail, it is possible that the transformer that you are using may have sufficiently high peak ripple voltage superimposed on the DC output voltage that it could lead to accelerated wear-out. Just a thought if that appears to be a problem.

 

[Dan Mosley]

Bill - actually yes, they have been burning out quick - 3 over the past few months - and one that just didnt light up at all - and I have been worndering why - thought that it may be just the lasers themselves - I went yesterday down to Radio Shack to see about a replacement transformer (better one)- They only had the same one - they seem to be good quailty so thats when I figured that it was just the lasers themselves.

I did order battery boxes along with the lasers that Dave is using as they were very cheap and maybe I should just go back to using them instead unless someone on here is using a better transformer - If so let me know where you go it ?

Its handy but if this is the problem ill just use the boxes......Thanks

 

[Bill Boehme]

Applied voltage is rather critical ... or at least it is when the applied voltage is over the rated value of the diode. A very small voltage increase can mean a substantial increase in current through the diode. One of the important differences is the source impedance of small batteries is much greater than it is for the power supply -- in layman's terms, the battery output tends to be self limiting because its output voltage drops as load current increases while the electronic power supply has no such current limiting mechanism.

I don't know for certain if that would solve the problem because the cause of the problem could be due to something entirely different. For instance, that particular diode might be intended for use with a pulsed driver rather than being continuously on or maybe it is intended to be used with a current limiting resistor. My hunch is that the power supply is eating the diodes.

 

[Dan Mosley]

yeah I see your point - its like what they call dirty power i suppose where this are peaks (surges/spikes) even in household currents - these transformers proably act the same where the battery can not. It is easier to use one but not at the cost of going thru diodes this quick so ill probably go back to the box until there is a more reliable device to use ........thanks

 

[Syd Sellers]

Too many volts...

Bill - actually yes, they have been burning out quick - 3 over the past few months - and one that just didnt light up at all - and I have been worndering why - thought that it may be just the lasers themselves - I went yesterday down to Radio Shack to see about a replacement transformer (better one)- They only had the same one - they seem to be good quailty so thats when I figured that it was just the lasers themselves.

I did order battery boxes along with the lasers that Dave is using as they were very cheap and maybe I should just go back to using them instead unless someone on here is using a better transformer - If so let me know where you go it ?

Its handy but if this is the problem ill just use the boxes......Thanks

Dan, you are now in my realm of expertise (Electronics)
Laser diodes are made to run at a certain voltage like 3 volts. Now this is 3 volts +/- 0.1 volts. And it has to be clean DC, not rectified unfiltered AC like what comes out of your Battery eliminator... You need to spend some bucks on a real good DC power supply.
If you are looking for a source of your laser diodes, I found one last night that can provide what you are looking for. Check this out http://www.apinex.com/

I am in the midst of building a copy of the Monster Hollower and I'm going to use one of their diodes. They even have cross hairs available.

 

[Syd Sellers]

I started looking around for a place to get a couple of new lasers from - Amazon has a few vendors listed and I was wondering what the difference is in them or if anyone uses something better ?

Below is the name of the one that I have bought in the past: this one fits in the holding hole in the arm perfectly so i assume 8mm is the exact fit and length does not matter
RED Laser Module 8mm X 25mm - 650nm 3 Volt <1mW
The above runs in the $35.00 range each

Then I see these other 2 listed as well -
RED Laser Module 8mm X 25mm - 650nm 3 volt
RED Laser Module 8mm X 25mm- 635nm 5 Volt <5mW
These run in the $7.00 range

Im not sure on why the price difference for a brighter light - wouldnt the 5mw be brighter and better ? I have a voltage transformer hooked up from a power cord to reduce it down -
It says 3-12 V - 1.A on the transformer and has worked well in the past so I assume it will work on the 5 volt lasers unless the 1.A limits it...not sure ?

Any thoughts on which would be better to buy ?....................or other vendors and what are others using in their Monster Hollowing rigs ????

From another site my understanding now is that the nm defines the color with Red in the 630-680 range - 1mw would be less bright then the 5 mw but the prices are all over - any ideas on why ?

I know Ebay has them in bulk but not sure about the quality or brightness etc............ anybody shed some light on the specs or suggestions ??

Thanks Dan

Dan,
I had a close look at your Pics and the one of the power pack you have, it shows you have it set at 7.5 or thereabouts. No wonder you are burning out the diode. Set that baby at 3V!!!
Syd

 

[Bill Boehme]

Dan,
I had a close look at your Pics and the one of the power pack you have, it shows you have it set at 7.5 or thereabouts. No wonder you are burning out the diode. Set that baby at 3V!!!
Syd

I couldn't tell from the out of focus picture anything about where it is set. I see something that looks like a little "pimple" at the 3 volt position and something else that looks like a "dimple" at the 7.5 volt position. Dan, did you use a meter to check the output voltage? I have been wondering what the original purpose of the "DC power supply" was.

BT, I checked the laser on my Steve Sinner hollowing rig and it is probably the same as yours. It has a brass focusing ring that is rather stiff to turn, the laser wavelength is 650 nanometers and the power output is less than 1 milliwatt. Interestingly, it is rated as a class IIIa (old rating system) laser. I suppose that it is because the focused beam power density may be greater than 2.5 milliwatts per square centimeter.

 

[Dan Mosley]

Yes the transformer was set higher when the picture was taken but i have had it usually set at 3v.........anyway ill look into it more and let you know soon......thanks

 

[abrown]

Do you know if the laser module is a simple laser diode or does it have a driver circuit? Laser diodes are typically current driven. They may quote a voltage, but that voltage is set to produce a given current with no source impedance. In addition, if the temperature changes, or the diode is coming off of a rejected lot for a specific customer (typically the case for cheap diodes), the material would be substandard and the diode current to voltage curve shifted.

This isn't the right forum to go into too much detail, but the current through a diode is an exponential to the voltage. As the voltage increases beyond the he knee of the exponential, the current begins to skyrocket, and the diode burns out. This happens REALLY easily if there is no protection on the diode. Any ripple, bump, hiccup, etc in the voltage supply could cause a current spike through the diode. This can even happen for changes in temperature as the diode will move it's IV curve around as the temperature changes.

Your choice is to either operate at a safe margin if you are just using voltage, or add some kind of way to dump voltage in the event of the current increasing. The best method would be to make a constant current source. You can google it and it's not too hard to make. you might even be able to find something from SparkFun or somewhere for an LED or a laser driver.

Second option, which is by far easier, is simply to add some resistance between the voltage supply and the laser diode. This will cause to you operate at a slightly higher voltage as you are dumping some power into the resistance, but it will protect the diode from fluctuations. Since I don't know exactly what laser you are using, typical 1 mW 650 nm diodes run about 60 mA at 3 V. I'd probably put a 20 Ohm resistance between the diode and the supply. This would drop about 1.2 V across the resistor forcing you to using a slightly higher voltage, but would protect the diode by limiting the current for voltage fluctuations. Since you intend to plug this in, the power lost is insignificant.

 

[Bill Boehme]

... and that is why I suggested that using a battery (two AA batteries or AAA batteries) is a better solution than using a power supply. When the current drain on a battery goes up the voltage drops which limits the increase in current.

Driving a forward biased diode with a power supply that has essentially zero source impedance is a good way to let the smoke out of the diodes and perhaps the power supply as well.

 

[Dan Mosley]

I ordered battery boxes and new lasers so ill see how it goes and let you know - There are transformers specifically for laser diodes that are for sale on Apinex part #AC110-220-DC3 - Not sure how it would work but may try it - either way thanks for the education and information on the topic it is interesting - Ill let you know how things work out with both the boxes and the Apinex mentioned.................thanks

 

[abrown]

I'm not sure the Apinex box will help you. I realize it is marketed as a laser supply, but it looks like a generic 3 V, 500 mA supply. What you really need is a way to limit the current of the diode to below the damage limit, which is probably <60 mA for a 1 mW red laser.

As Bill suggested, batteries should do the trick. Alternatively, adding resistance to your voltage supply would do it too. A trip to RadioShack and about 25 cents.

 

[Bill Boehme]

I looked at several of the red lasers under one milliwatt and the current consumption varied from 20 mA to 35 mA. Also, all of the ones that had any details said that there was also a driver -- I presume on the same chip. The driver adds an unknown factor, but perhaps the actual voltage to the diode could be much lower than the supply voltage and the driver could be operating as a current source.

 

[Dave Mueller]

Not to complicate things, but lasers also need current limiting, usually a resistor in series. Most of the laser modules have built-in current limiters. The ones I linked to earlier in this thread seem to have limiters, because mine have noit burned out since I installed them over a year ago. Without a limiter, they would probably burn out quickly. I also agree with the use of batteries, as they are a maximum stable voltage with no ripple. As the battery discharges to a lower voltage, it does no harm to the laser, just no light. Battery replacement is a small price to pay to eliminate laser replacement. Finally, laser modules with the ability to focus is pretty useful. These lasers are edge emitters, which produce an elliptical beam shape that requires some sort of focusing to get a spot at a specific distance.

Sorry about all the techno babble, just thought it would help.

Dave

 

[Bill Boehme]

..... Sorry about all the techno babble, just thought it would help.

Dave

That's OK, I speak techno babble, too. 😀

 

[Rob Wallace]

Dave:

Some of us are here for the discussion on turning AND the techno-babble.....

.....keep it coming!

Rob

 

[Dan Mosley]

I like the discussion on both its a good learning experience to know more about diodes and transformers and how they work -
Well I have both on the way and ill test out both ways and post what happens..............thanks for the information