Eleksmaker 3500mW 350nM UV Laser

Eleksmaker 3500mW 350nM UV Laser

I recently purchased this "3.5 Watt" laser from Banggood during one of their sales.  I figured for $50, what the hell.
Being the geek I am, I figured I'd analyze the build construction and performance. Without further adieu, here are my initial findings.

Laser Controller:

Of course, it arrived in a cardboard box with no packing material. The driver module and Laser module were laying against each other so the two connectors got mangled and the electrolytic cap behind them got badly scuffed/scraped.  Not sure if I trust the cap (not sure I would if it were undamaged either) due to this damage.

The solder appears to be lead solder, but it never said is was ROHS compliant anyway. The quality of the soldering is surprisingly good with nice filets and very little voiding at the bottom solder pads.

Laser Module:

The laser comes with a visible purple targeting laser which is active when the UV laser is not on.  I am not sure if it turns off when the UV laser is on, or not.

The Laser module is cooled by means of a single small fan mounted on the rear of the laser, with the air blowing in the direction of the laser emitter.

The beam is focused by means of a small rotating lens assembly and it appears to focus down to about a 0.5mm point.

Laser Diode:

In the photo below, you can see the UV and Visible purple laser diodes.  

Here, you can see that the laser diode assembly is mounted to a copper block, which is press fit into the extruded aluminum heatsink. There are no other devices inside the heatsink.  I suspect that this could be made into a more efficient heatsink by halving the length.  This would allow the fan to cool more efficiently near the source of the heat.  I doubt that there is much gain in thermal regulation when the cooling source is so far away from the heat source and has limited flow to begin with.

Lower portion of the heatsink. The large black item is the copper mounting for the laser diode.

Upper portion of the heatsink.  The laser diode assembly on the left and the fan on the right.

The next 4 images are progressively closer views of the laser diode assembly and the heatsink.  Note the bright ring between the laser assembly and heatsink. I am hoping this gap is filled with a thermal paste, but I doubt it.

Testing:

I performed a power measurement to see just how close to 3500mW this laser actually was. As you can see in the images below, the answer is "not very close at all".

I initially measured with the beam focused on the meter and reached 2107mW.  I thought that maybe the lens was absorbing some of the light so I removed it. Now the beam was too wide to fit on the meter, so I mounted it straight up and put it directly on the meter face. This gained me another 29mW.  So at a 100% PWM, no lens, minimal air gap I have a total output power of 2136mW from a "3500mW" laser. 

I am currently waiting on the response from Banggood to see what they say about the 30% lower power than advertised.  I am not sure if it is just a 2500mW laser that got packaged wrong or if they are really trying to pull a fast-one on their customers.
Granted, for $50, a 2100mW laser is still not a bad deal, just not what they claimed I would be getting.


UPDATE: I looked closer at the details listed on Banggood's website, for this item.  It is definitely misleading, but it does state 2W.  I am not sure if this means that most units are around 2W, but some are as high as 3.5W or if each unit runs at 2W, but in microbursts they put out 3.5W.

UPDATE #2:  The response from Banggood's customer service was "...sorry to tell you the power will not always at the highest value.For it could be used a long time and safe,the power will be low."  They also offered a more-than-fair refund to compensate for the damaged controller.  While I think that the Banggood website is misleading with the information they provide for specifications, I think they have some excellent customer support. I remain a happy customer.