New "inmproved" reci tube series - W series

[Dave Sheldrake]

Ok - that makes sense to cap it in firmware, but is it easy to use a multimeter to find out which value to cap it at?

Yes but electrics are well outside of my paygrade, I've used a meter to check tube amps at the negative but I'm nowhere near qualified enough to suggest it to somebody else or any method of doing so.

A couple of belts from a 150 watt supply kinda keeps me away from playing with them laser beams, physics...fine but not electrics for me

best wishes

Dave

[Robert Silvers]

Is there some low cost thermopile for a 80-150 watt tube?

[Rich Harman]

...the easier way is to run the machine at <80% power on the control panel (you can set the max power on the DSP rather than adjusting the tiny screw on the PSU)

I replaced my main board quite a long time ago for the newer model. With the old main board 90% power was about 25mA. With the new board 90% was about 18mA. No other changes had been made. In order to make a 90% setting in software fire the laser at 25mA I had to adjust the little screw on the power supply.

The other machine which came with the new style main board also was firing "weak". Adjusting the power supply allowed the machine to fire at greater power. Both machines are always kept at or below 25mA.

Without an ammeter it would be difficult to know if your machine's power supply is adjusted correctly. I wouldn't trust that a software setting is an accurate reflection of the true power going to the laser.

[Dave Sheldrake]

Mine is a Coherant LabMax-TO with a 300PM-F50 head that measures to 300 watts but they aren't cheap at nearly $4,800 new,
I believe China do some at around $1,000 that will measure up to 200 or so watts (but are +/- 5% so not very accurate) or second hand maybe an LD100 head with a 212 monitor from Coherant going about $1,000 (up to 100 watts) (and are very accurate if calibrated) A 30/150 Ophir head is going to run about $500 alone but well worth getting Ophir rather than generic Chinese.

best wishes

Dave

[Robert Silvers]

How about aiming the laser at a container of water? Weigh the container on a gram scale. Use a very accurate thermometer (bomb calorimeter).

http://www.novatech-usa.com/Products...FQ6f4Aod3DEANQ


Say for example if 380 grams water went from 75.6F to 100.5 F in 300 seconds...


24.222 C to 38.056 C


(38.056-24.222)*380*4.19/300

That would be 73.4 watts.

This thermometer is probably good enough since we only care about the change in temp and not absolute readings:

http://www.amazon.com/Taylor-Digital...al+thermometer

I am not sure the ideal container - probably thin black ceramic, but since glass is opaque to this wavelength, an ordinary glass may be ok (though it may reflect too much?)

[matthew knott]

Cheap power meters are basically a large block of Metal with a thermometer stuck in them, Normally calibrated in time! Set the dial to zero, fire the laser for a set time (20 seconds was common) into the block, read of the power in Watts. Simple and Ok for a reading. Thermopile gives you nice real time readings, we have a Ophir that plugs into a laptop, used to use it for setting optics in the laser resonators, nice but expensive. I flew to munich a few weeks ago to the LASER World of PHOTONICS 2013 show, every one and everything to do with lasers there (including Reci). Ive seen the new Reci tubes, they were firing 2 into a brick

for some reason, the new PSU looked very sexy, with an LED display.

[Dave Sheldrake]

I wouldn't trust that a software setting is an accurate reflection of the true power going to the laser.

True Rich, I'm just very cautious about telling people to fiddle with the adjustments on the PSU without having an idea of their electrical skill levels. On a side note, I saw Weike are now reverting to the older 6515 cards rather than the 6525...that's kinda worrying...

best wishes

Dave

[Robert Silvers]

I see. There is one for $55 on eBay (it directly reads in watts up to 100). Seems sketchy. I would only trust it if I saw it work side by side with something higher end.

[Dave Sheldrake]

Ive seen the new Reci tubes, they were firing 2 into a brick

It scares me when I see the methods some of the Chinese companies use banks of tubes on a desk (without sign of an earth point) all firing against the wall to make sure they work

Shows are great fun, I recall one well known Western laser company expounding how fantastic they are and how their new machine was going to "revolutionise the industry" only to see his face drop when somebody shouted "Dude, sorry to interrupt but your machines on fire" (waves: Hi Gordon)

best wishes

Dave

[matthew knott]

I see. There is one for $55 on eBay (it directly reads in watts up to 100). Seems sketchy. I would only trust it if I saw it work side by side with something higher end.

Yeap, thats the kind of thing, they work fine if calibrated, way better than nothing and you can use them as a reference point, somewhere i have some of those little Synrad laserwizard things http://www.synrad.com/pw/, brand new that where surplus stock, wonder where i put them!

[Dan Hintz]

Yep, picked up a Power Wizard myself a few years back... less than half price, if memory serves.

[Chuck Stone]

Yep, picked up a Power Wizard myself a few years back... less than half price, if memory serves.

Care to rent it out for a few days?

[Dan Hintz]

Chuck, I think you can rent one from Timberbits for a reasonable price... it's worth it when you think your tube might be failing.

[Jonathan Brown]

You can also make a crude thermal power meter with a block of black anodized aluminum (or coated with something that will absorb the co2 wavelength), a thermistor, and a power resistor.


I did this before I got my Synrad Powerwizard 250 watt meter and it turned out to be quite accurate (within 10% IIRC) over a range of laser power. Takes awhile to calibrate the thermal profile of the block/thermistor with the power resistor though.

[Chuck Stone]

Chuck, I think you can rent one from Timberbits for a reasonable price... it's worth it when you think your tube might be failing.

David has them? I didn't know he was involved with lasers. I'll
have to give him a call next time he's sending an order..