Ophir 20A thermopile head - info wanted please

[greenalien]

No idea if there's an op-amp inside, apart from the BNC connector on the back, there's a small almost-flush nut with a slotted screw inside, could be for adjustment of something or could be holding the entire stack together.

So far, the only measurements I have conducted are to measure the internal resistance - around 2k - and measure the voltage when hitting it with a laser, which looks like 0.3mV/W approximately.

I'll try smoking it with a carefully-applied candle and see if that makes any difference.

[mixedgas]

if there is no 4 pin connector and only a bnc, its not amplified but self generating.

Steve

[greenalien]

self generating

That seems right, but the output is pretty low, 0.3mV/W. Does that sound about right for thermocouples?
Robin has kindly offered to investigate putting a high-gain op-amp stage on the front of one of his die4thing boards, which should give a more useful measuring range than my multimeter.
On the plus side, it doesn't look like I'll be risking overcooking it with any of my lasers anytime soon, as I think it'll handle laser powers up to 20W; it remains to be seen if it's sensitive enough to give useful readings at lower power than 1W, but I'm hopeful that it'll still be a useful tool for comparing relative power.

[dera236]

Hi all

Have Just purchased a OPHIR 20C power head, and i have a few questions regarding them!

Does any one know what the output is like on these I.e. what is the mV output range.
Does the signal swing +/- W.R.T 0V?
Does the signal in the quiescent state with no laser light entering the device sit at zero or is there an offset?
What is the maximum swing in mV when a 0-5W laser is projected into the device?
If anyone can shed light on any of the above no pun intended it would be most useful as I would like to scale the output to give say 1V = 1W
Having access to a few real life figure will allow me to design up the electronics to achieve this.

Regards

K

[lasersbee]

Hi all

Have Just purchased a OPHIR 20C power head, and i have a few questions regarding them!

Does any one know what the output is like on these I.e. what is the mV output range.
Does the signal swing +/- W.R.T 0V?
Does the signal in the quiescent state with no laser light entering the device sit at zero or is there an offset?
What is the maximum swing in mV when a 0-5W laser is projected into the device?
If anyone can shed light on any of the above no pun intended it would be most useful as I would like to scale the output to give say 1V = 1W
Having access to a few real life figure will allow me to design up the electronics to achieve this.

Regards

K

There is no need to post Identical questions on two different
threads...
Patience Grasshopper...


Jerry

[dera236]

OK Jerry.

Apologies, Posted here first then found a more appropriate thread. so posted there as well but forgot to remove this one!