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200mW 650nm Red Laser

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TheMerovingian

Mon Feb 07 2011, 09:52PM

Registered Member #14 Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383

Here is a small laser project using a laser diode salvaged from DVD burner housed in a 5.6mm laser diode housing with focusing lens. The diode holder is housed in a circular heatsink to keep the diode cool at those power levels. THe laser can easily burn things, ignite matches, expecially if focused. It can punch through a cd black plastic case in a minute not focused and in 5 seconds if focused. The power is close to 200mW using a solar cell short circuit current to calculate the photons striking the cell taking into account the IPCE (Incident Photon to Current Efficiency) of a monocristalline solar cell and the wavelenght defocusing the beam as much as possible to avoid saturation. It probably can be pushed past 250mW but the life expectancy will the shorter and the power consumption will rise, eating away batteries too fast.

The circuit is a simple constant current power source regulable between 0 and 750mA

Here are some photos of the device.

Gregory

Mon Feb 07 2011, 10:10PM

Registered Member #2922 Joined: Sun Jun 13 2010, 12:08AM
Location:
Posts: 226

OHH, very good work man! A beautiful setup.. and wiith this setup you can upgrade putting a bigger laser!

TheMerovingian

Mon Feb 07 2011, 10:20PM

Registered Member #14 Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383

Yes, the laser is easily replaceable and i have 9 module housings for other laser diodes. I think that i can use the sistem up to 1W laser diodes. In case i find a bigger laser diode the current module will be downpowered and used as laser pointer or point-focused and used as a neat fuel-free lighter :D

Patrick

Mon Feb 07 2011, 11:01PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Is the red beam length visible due too dust or is it the Rayliegh effect?

TheMerovingian

Mon Feb 07 2011, 11:50PM

Registered Member #14 Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383

It is due rayleigh (raman is way too low on intensity) forward scattering probably, dust particles appear as small point-like light sources. At these powers the scattering is very strong even at red wavelenghts. My 3.5mW red laser pointer for comparison has almost invisible beam. I would like to build one using a 405nm blue ray laser (they are 150mW nominal), the scattering is stronger at these wavelenghts. I can find one for 12 Euros here in italy.

dmg

Wed Feb 09 2011, 05:36AM

Registered Member #2628 Joined: Fri Jan 15 2010, 12:23AM
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Posts: 627

Pretty nice!
I dont have enough reds myself, im considering building one, probably the same power levels as your own, but in a handheld style.
Im using a far smaller heatsink and driving a 445nm diode @ ~2W, without any heating issues, I wont doubt for a second your heatsink can handle high powers.

my 650nm diode is of an LPC-815 sled.
I wonder where did you get your diode from?

TheMerovingian

Wed Feb 09 2011, 09:06AM

Registered Member #14 Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383

GBD wrote ...

Pretty nice!
I dont have enough reds myself, im considering building one, probably the same power levels as your own, but in a handheld style.
Im using a far smaller heatsink and driving a 445nm diode @ ~2W, without any heating issues, I wont doubt for a second your heatsink can handle high powers.

my 650nm diode is of an LPC-815 sled.
I wonder where did you get your diode from?

My diode came out of a samsung 16x DVD burner, i'm searching for open can types though (400mW beasts) from 22x DVD burners to replace it. I have blown one diode from a 16x LG burner becauce of a capacitor discharge (sic.) . WHere did you get the 2W beast?

Your LPC-815 open can diode can be probably pushed past 250mW at 400mA. Are you using the ayxis modules? Beware of acrylic lenses, they get blown at > 1W powers.

My diode is powered at 430mA obtaining somewhat higher than 200mW, but my measuring methods aren't that precise.

Thermal measurement using thermistor feedback heating (constant temperature calorimetry) gives 160mW but the adsorbing body is not totally blackbody

For solar cell i used the following method.
Isc-cell [C/s] = PhotonFlux [mol/s] * IPCE * F [C/mol]

Isc-cell = solar cell current
IPCE = incident photon conversion efficiency [0.68 @ 650nm]
F = faraday constant [96485]

Power [W] = PhotonFlux [mol/s] * N [1/mol] * h [J*s] * c / lambda

N = avogadro number [6.022E23]
h = planck constant [6.626E-34]
c = light speed [approx 2.99E8 m/s]
lambda = 650 nm

I got a cell short circuit current of 87mA -> photonflux = 1,326E-6 mol/s ->

Power 243 mW

I need la laser power meter

Dr. ISOTOP

Wed Feb 09 2011, 10:27AM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

The 2W beasts are the new 445 nm diodes from DLP projectors, available on Ebay for ~$60.

dmg

Wed Feb 09 2011, 12:25PM

Registered Member #2628 Joined: Fri Jan 15 2010, 12:23AM
Location:
Posts: 627

2W is very overdriven.
even 1W is still driving them above thier standard operation (IIRC in the projector they are 1W pulse, not CW, CW ratings are only 500mW)
I extracted my diode out of an XJA-140 projector.
as bwang said, they are sold online for about that price. but if you look on LPF you can find them ~40$
but my case I just did it myself rather then buying it from someone.

I do not use aixiz modules, they are quite poorly made IMO, and are a pain in the ass to work with.
I either use a o-like module (black thing with fins) (which I compared to aixiz, o-like has a better dissapation and faster convection rate, bieng aluminum and anodized rather then chromed brass.
either that, or I machine my own modules with a screw type holder rather then pressfiting the diode. this makes removal alot easier.
for the lens, yes, I am aware that acrylic will melt at lower powers, and generally I always use glass regardless of power level. (also, if you want anything good beam wise from these 445nm diodes, an anamorphic prism pair does quite nicly for beam shaping/partial correction)

For your messuring methods, they are pretty good IMO as in better then nothing. A good LPM is expensive, but your method is pretty nice to get a power reading.

Conundrum

Wed Feb 09 2011, 05:57PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

apparently the best way to protect them (this tip was given to me over PM) is to put a transzorb across them.
Interestingly a green LED in antiparallel as well helps prevent ESD to some extent.. so does a 10K resistor.

-A

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