TwoTrees T20 1064 nm Engraver - 2 W average, 15 KW peak power.

[Laser57]

Here's a link to a great video regarding a 1064 nm 15KW peak power engraver offered by TwoTrees, among others who appear to be selling the same module branded with their own names.

https://www.youtube.com/watch?v=UpuN0dS23Nw&t=229s

Here's a photo of what is inside. 808 nm pump diode reported by the manufacturer to be 8 watts output @ 1064 nm 2.5 watts measured average, 18 KW peak pulse power measured:

Attachment 61149


In the above photo, the red and black wires are the DC power input leads to the laser diode chip which appears to have been either epoxy or solder mounted to the brass. If the screws to the PC board feeding the diode are removed, when wiggling the little board I found the laser diode chip itself won’t move from its position being permanently fixed to the brass. Additionally, due to the gold wires tack welded to to chip, if the diode ever fails I don’t believe the unit is meant to be repaired, instead replaced as repair would likely cost as much or more than a new unit.

Located at the output of the ~808 nm laser pump diode is a FAC lens glued to the chip which is likely cut from a piece of fiber optic transmission line as is commonly found in cheap lasers to reduce the beam spread from the fast axis of the diode. I measured the power output from the FAC to be more than eight watts of power which is focused into a separate mount containing a ND:YAG. This YAG appears to have a high reflectance/HR mirror deposited upon the face of the crystal which has high transmittance (low loss) to 808 nm from the pump laser diode, but HR to 1064 nm (forming a cavity with the OC). The opposite or output end of this YAG has an AR coating.

Following the ND:YAG is a solid state CR:YAG Q-Switch mounted in its own holder which within the cavity is needed for the production of high peak power short nanosecond pulses, otherwise the output would only be low power CW. At the output of the Q-Switch, is the OC or output coupler optic which is partially reflective to 1064 nm completing the cavity. The OC mirror has a thin brass cone attached to it which swivels inside the assembly and is then locked into a position via three screws when the optic is parallel with the end of the ND:YAG crystal, allowing the cavity to produce the required gain to overcome losses and output a beam of collimated 1064 nm near infrared light.
I measured the average output power at 1064 nm to be about 2.4 watts from each of the two modules I purchased, more than the specified 2 watts of output. The total current draw at this output is 2.7 amps at 12.0 VDC into the driver board with TEC.

Under the brass L is a TEC or thermal electric cooler, due to the white silicone the wires to the cooler are difficult to see in these photo’s.

More info and photo's here: https://www.laserdiscourse.org/t/two...tp-crystal/448

Cheers, Chris... AKA Laser Project

[mixedgas]

Having had my hands on one for a while, they are fun, but due to the high energy Very, Very, Very Dangerous from both a direct hit in the eye and stray or secular, mirrorlike, reflections. reflections. It is Class Four, and not a toy.

No one should be in the same room without OD6 Goggles on to protect their eyes.

I would not use it on an unenclosed engraver either, the peak pulse power is vast.

Steve

[Laser57]

Agreed. My goggles are OD 13+ at 1064 nm. One good thing about the 22 mm focal point, after that it expands fairly fast, still very high energy. I wonder though, how many mm the beam would need to be expanded to reduce the hazard to that of a 1 watt CW laser @ 4 mm diameter, I will calculate it soon. Of course that wouldn't make it safe, would need to be reduced to a very few milliwatt at eye aperture (if not focused to a point which the lens of the eye can aptly do to coherent light). Not a toy, any way you look at it, don't without proper handling and eye protection.



From Les' Lab YT Channel:

[Laser57]

Bump, I edited in more information to my post after tearing down this laser to confirm the coatings on the ND:YAG as well as the mechanism used to adjust the OC, simple but ingenious! I also confirmed the pump diode output power to be close to the claimed amount of power, per the manufacturer. I measured a bit more @ 8.25 W.

Question, can someone advise me on a good way to measure the peak power of this laser? Is it simply, or only measuring the pulse width, repetition rate and average power and calculating from that, or is there a meter which does all of this for you?

The Les Lab video I linked to in the first post here shows using an O'Scope to measure pulse width and repetition rate, plus the peak voltage response from a photodiode to calculate the peak power. I believe the photo diode isn't needed if you have a LPM to measure the average power and already know the pulse width and rate, which he provided with his tests.