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FrozenGate by Avery

DIY Pre-Calibrated LPM for under $100.00....

Joined
Sep 20, 2008
Messages
17,635
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113
That's right... I said No Calibration required...

28007d1278946678-diy-pre-calibrated-lpm-under-100-00-redinput.jpg


We have been playing with the OPHIR 20C-A Thermopiles...
that were on sale on eBay a while back... They were new
surplus old stock heads...
I made a deal with Kenom for a few heads and have some
more from the Kenometer Lite's I purchased from him..

They are the same ones that are used on the Kenometer Pro
and USB series...

These Heads come with a preamplifier and calibration circuit
already built into the Head and comes already Calibrated to
1mV=1mW... You don't even need to calibrate them...

All you need to do is supply a split supply and a Voltmeter..
That's all.... anything else is not really required to have
a reliable calibrated Laser Power Meter...

Here is a parts list to build a ~$100.00 LPM...
(your mileage may vary)

1) 2pc 9Volt Batteries -------- $ 4.00 (we used rechargeables)
2) 1pc DPDT toggle switch --- $ 1.00
3) 1pc DMM--------------------- $10.00
4) 1pc OHPIR 20C-A head -- $40-$150 (used) ($390.00 New)

We checked the current draw from the 9Volt batteries and
with no Laser input and at 1000 mW input each battery needs
to supply only 4.7mA...
The batteries will last quite a while before needing to be
changed or recharged.

You can see the simplicity of the circuit in the pics attached and it
is easy enough to follow..
The only thing that we are not sure of is the Label on one of the
heads (see Photo). It notes the Part Number as 20C-A-1-Y....
Looking at the Data Sheet we found on line...

20C-SH_20C-A_20C.pdf

The 20C-A means it was calibrated at customer selected wavelength...
The -1 means that the output it is 1V/1W
The -Y means that the head was calibrated for YAG 1064nm

That Part Number can only go to 4 Watts Free standing and up
to 5 Watts max with some heatsinking...
If the model number were 20C-.4-Y then... with a lot more heay
sinking the heads could read up to 20 Watts..

Even though they were calibrated for 1064nm... the calibration
seems to work well for our uses...

Now all you need to do is find some OPHIR heads...:cool:
BTW... we contacted OPHIR and in quantities of 100pc we can get
them for $250.00 USD each Brand New...

(It is to be noted that the Switch as wired in the Photos is not
correct... The DPDT switch must cut both Battery supplies not
just the common as stated below.
)

Jerry

You can contact us at any time on our Website: J.BAUER Electronics

------ No Input ------ 200mW Dilda -- Serial Number
 

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damit......wish i saw this before i made my lpm
and now it needs a new tec o_O
dam
so are u selling them??
 
No... this is just a quick project that we put together
for the Members here...
If they were for sale they would be in the B/S/T section...


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
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fifty dollars? i want.

How accurate are they compared to die4thing,kenometer,beemeter?
 
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fifty dollars? i want.

How accurate are they compared to die4thing,kenometer,beemeter?

It should be just as accurate. The die4thing and Laserbees are calibrated using a calibrated LPM, and Kenometers use these.

-Trevor
 
fifty dollars? i want.

How accurate are they compared to die4thing,kenometer,beemeter?
They are as accurate as the calibration... One is not
more accurate than another if the calibration is done
right..

BTW... the total above is a bit higher than $50.00..
and can be over $100.00 if the OPHIR head you find
is expensive..


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
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I would recommend getting a DPDT switch to break at least two of the power connections to the head. As it stands now there is still +18v being applied to the head, just with no ground when it is switched off.
 
Seems like a good project at a reasonable price to me. I don't know the exact specs on all its parts, but it dos seem like a nice diy build as long as the sensors are available.
 
I would recommend getting a DPDT switch to break at least two of the power connections to the head. As it stands now there is still +18v being applied to the head, just with no ground when it is switched off.
Obviously you are correct and the unit we took the pics of had
a DPDT switch installed after the pics were taken to cut the 18V
circuit... (fixed the parts list above.. :yabbem:)...
Good catch....:cool:


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
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Try eBay... or do a Google search... or maybe some members here
or on other forums may have one...


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
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i shall try get a TEC for my MM LPM. if its a total fail il donate it to landfill and buy one of these when (if) i get enough money
 
Yes I know, Zombie thread, but with all the talk of DIY LPM I just ordered a OPHIR 20C-A off of Ebay. At least that will give me something to measure my output with. Then maybe I can incorporate into some of the other cool projects here on the board.
 
boo. hiss. necro-post. I was expecting you to tell me where I can find my $100 LPM. :yabbmad:
 


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