how to measure temp in vacuum chamber/BHO extraction?

[matt11]

When measuring the temperature with an IR temp gun, I should be measuring the BHO puddle itself right? But how do I measure it while its purging?i can't through the top glass. I am going to be putting the vacuum chamber on a griddle.
What do i do? Do I stop the pump and halt purging, and open the vacuum chamber- take the temp then close and resume purging? I would think I would have to do this frequently to get the temp dialed in. Is it counterproductive to keep stopping luring to open it up to measure temp?
Where and how should I measure the temp?

 

[Phaeton]

I used a probe style sensor that came with a thin stainless steel woven shielded wire connecting it to the readout.
The sheathed wire was run through a groove in the gasket and sealed with high temp solvent resistant automotive silicon gasket maker.
It held up for a couple years of careful use.
Cost was less than $50 USD.