5W 808nm laser Portable Laser advices & help Pleases

[Hank]

So after my second year as EE at NCSU, i'm ready to construct a high power 808nm portable laser. This is the biggest and most exciting project i've ever taken, so i'd really appreciate some advices/help. Lathing and driver construction will probably be the biggest issue i'm facing. I can get access to a lathe/mill but i have no experience with them. Anyways, feel free to point out any my flaws.

I'm planning on purchasing this diode:
4 Units x 5W High Power 808nm Laser Diodes -

They also have a 980nm which is completely invisible. But I'll prob get the 808nm to3 just so i can at see where the laser is point at.

Laser Description/Objective
So i plan to fit everything including the diode, heatsink, driver, batteries, gears, into an ~3x3x10 inch aluminum box. I also want the focus of the laser to be adjustable.

The aluminum box is divided into three sections.

1st section will contain the diode which is fitted into an custom made heatsink. I'm also considering the use of petier devices and thermal paste. Within the first section i'm also planning on building a wormgear so i can control the focus of the diode on top of the aluminum box. I will also caliberate and mark the top gear that is showing outside on the box with focus distances. So users can rotate the gear with their thumb and focus the laser beam onto an object as long as they can estimate the distance.

2nd section will contain the driver. It will certainly need to be capable of handling 5 amps of current. To my knowledge, neither the lm317 or the 350 will be able to work. Any design suggestions? I understand i can porbably get a driver on a PCB for decent price, but i really want to build everythign from scratch so i can brag about it to friends and impress my professors during office hour. I also like idea of taking on such challenges.

3rd section will include ~3x 18650 batteries in parallel setup in order to support the current draw. The battery holder is kept in fixed position in the top half of the 3rd sectio. The bottom half will include an ignition lock and a power button connect to the back. I will also include 1-2 LEDs to signal whether the saftey is off or the laser is on.



I'll keep everyone up to date with the project as well. I'm not an artist, but i'll try my best sketch out a basic design within the next few days and post it up. In regard to that, is there a way i can post images directly onto this forum? Sorry i'm kinda of a newb in this forum.

 

[Ramsey_innovations]

Just as heads up these are multi-mode so collimation to achieve a Gaussian beam profile will require more than a simple aspheric lens. Also looking at the info on the link provided I'm doubtful that you will see an output of 5w at 5 amps input current. My c-mount does about 3.5w optical output at 5 amps. if you are considering using this as a pump for dpss the fact that its +/- 10nm will definitely pose an issue.

All that being said these are powerful lasers so if you do purchase them be VERY careful IR light is deceiving. DO NOT even consider powering them without proper eye protection. In my opinion these are overpriced I paid $75 for my c-mount about 2.5yrs ago and these being listed 4 for $500 is quite steep.

Anyway, best of luck to you and happy holidays!

 

[Hank]

Just as heads up these are multi-mode so collimation to achieve a Gaussian beam profile will require more than a simple aspheric lens. Also looking at the info on the link provided I'm doubtful that you will see an output of 5w at 5 amps input current. My c-mount does about 3.5w optical output at 5 amps. if you are considering using this as a pump for dpss the fact that its +/- 10nm will definitely pose an issue.

All that being said these are powerful lasers so if you do purchase them be VERY careful IR light is deceiving. DO NOT even consider powering them without proper eye protection. In my opinion these are overpriced I paid $75 for my c-mount about 2.5yrs ago and these being listed 4 for $500 is quite steep.

Anyway, best of luck to you and happy holidays!

Thank you for your advice. It's very useful. Well do you have any recommendation to what laser diode i should be using instead? i don't plan on using it for dpss for now. just trying to build a high power portable laser. The more power the better. I guess it will also have to be single mode if i can focus it using just a aspheric len. And yes i will be using proper eye protection.

 

[Ramsey_innovations]

Personally I would recommend either a 405nm or 445nm diode. Although the 445nm diodes are multi-mode they can be collimated with an aspheric lens, however the output will be in the shape of a bar not circular. If that doesn't sound too appealing then I would definitely go 405nm. I've had a 10x bluray 405nm diode for about a year now that has been my absolute favorite. You can buy one here www.rayfoss.com for $55. I have mine set to output about 600mw which might not sound like much but let me assure you it burns very well. It will light a wooden match stick (yes the bare wood end) in seconds. In conjunction with the 405-g-1 lens that jayrob sells the divergence is quite low and output power is maximized. With the g-1 lens there is a bit of side splash to the output but IMHO its well worth the increased energy density.

Here are some pro's and con's of each:
445nm diodes
-Pro's
Output powers up to 2w
Greater visibility of 445nm wavelength vs. the 405nm
-con's
Generates a great deal of heat
less appealing spot shape
greater divergence

405nm diodes
-pro's
able to fluoresce many things
lower divergence vs. 445nm using aspherics
higher energy density
output powers in class IV (>500mw)
very efficient
-con's
less visibly brilliant vs. 445nm
requires higher forward voltage

Both will require a glass lens for collimating, I don't recommend acrylic.

If anyone else can add to this list please feel free to do so!

You want to check out this thread for recommended current levels http://laserpointerforums.com/f38/blu-ray-445-diode-test-current-levels-long-life-44746.html

Hope this gets you going in the direction, happy lasing to you!

 

[Meatball]

That fast axis divergence described by the listing tells me there is no FAC on those diodes.

Ramsey is very right when he tells you that the collimation of the diode will be a project all on its own!

High power is available everywhere, but it really depends on WHY more power is better.

What is the end application? There still may be good reason to stick with 808...

 

[Hank]

That fast axis divergence described by the listing tells me there is no FAC on those diodes.

Ramsey is very right when he tells you that the collimation of the diode will be a project all on its own!

High power is available everywhere, but it really depends on WHY more power is better.

What is the end application? There still may be good reason to stick with 808...

It is quite immature, but the application is simply burning stuff. I've always figured a 1w 808nm laser diode will burn much more than a 1W 445nm or other visible light laser diode simply because 808nm is infrared meaning it is pure heat. But i can't think of an object that will reflect heat waves. 650nm for example, won't burn anything that is not dark in color. 405nm on the other hand will burn objects with a bigger color range. The problem with visible light is that some of it is always reflected. Only a portion is absorbed by the object and turns into heat. So i've always thought 808nm would be absorbed much more by the object since it is already heat. Am i wrong?

With that being said, i want to build the most powerful portable labby laser with money not being too much of an issue. I already own two arctic (one w/ smartswitch and one w/o) and a bunch of other lasers. I'm also trying to build a 1w 445nm on my own with olike driver into an ultrafire so i can focus the beam. Correct me if i'm wrong, at the point of focus, the power could be 10x more powerful as the arctic. If so, the heat accumulated at that point of focus should be greater than 10x since heat is dissipated over time. The arctic 445nm was measured to be about ~750 mW using my laserbee. If i can get a 5W 808nm laser diode focused into the same size i could with an 1W 445nm laser diode i could be generating over 70 times more heat PER SQUARE MM at that particular foco point than the wicked arctic. At which point, the laser won't burn anything, it will simply cut.

to be honest, the way i'm analyzing this all sounds reasonable when i ran it over and over in my head. But as i'm typing it up, it begins to sound ridiculous. So by all means, point out what is wrong with it.

 

[Ramsey_innovations]

So i've always thought 808nm would be absorbed much more by the object since it is already heat. Am i wrong?

To answer this in brief, yes your wrong. I have a tough time getting my 904nm IR C-mount to burn light colored wood at all. I can see how you could come to this conclusion, however with the exception of 10.6µm, far IR, known as the "heat" wavelength infrared is usually not absorbed as diversely. For example a 405nm or 445nm can burn plain white paper at relatively moderate power levels with proper collimation. This would require very high energy densities at most IR wavelengths. Here is a link to an article that touches on this subject Interaction of Radiation with Matter
One other fact to bear in mind is that the lower the wavelength the higher the energy that each photon has (some more info Energy of a Photon). Also the lower the wave length the smaller the achievable point of focus. This is why a bluray disc can hold so much more than a cd.

Never the less if your going to go IR and your not afraid to go big you could do something similar to Hemlock_Mike (http://laserpointerforums.com/f43/starwarz-co2-power-47504.html) and still remain portable. In fact I would encourage this route if your up to it. If I had more time I'd like to build myself one those bad boys.

 

[vk2fro]

Why not build yourself a dual or quad 405 or 445 - you'll have several watts to play with, it will be insanely bright, and one of the forum members built a quad and he can set wood blocks alight with it.

The beam on a 405 or 445 will be MUCH easier to tame than a 808 diode.

The electric current requirements for the dual or quad build will be less or on par with the 808 diode as well.