You need to make an input stage for that peltier cell, for use it as LPM ..... a 36 junctions peltier cell does not have enough output alone, for hook it on a DMM and made a LPM ..... you need at least a 15 to 20 times amplification (for an easy use, a single op-amp circuit is enough ..... and using a double op-amp you can use the second one as output buffer / zeroing circuit)
Also, the SLIP Plate paint you used is not the better thing, you need to cover the "reading" face with a paint that have the maximum possible adsorbing index for light ..... like some matte paint for high temperatures, or a very thin piece of matte black anodized aluminium, thermally glued on the face ..... and also , need to couple the opposite face to a big mass heatsink (and this may mean scraping away all the solder from the back face, for make it the more flat possible)
I got some decent results with some 10x10mm 60-junctions plates, and also better with an 8x8mm 62-junctions one (but this last one was found for pure luck, and i'm unable to find any others similar ..... maybe was a custom model, don't know), followed from an op-amp input stage ..... not a professional instrument like a thermopile, but decent enough as DIY units
..... LESS good results with 20x20 ones .....
BTW, the shop where you buy them, does have any 10x10mm TECs with 60 or more junctions, for any luck ?
I'm sure you'd get a BIG GB going on CPF if you wanted and showed your stuff here as assurance of rep.
