Where do you mount this device without destroying it and melting solder on the supporting
chips in the toner work PCB heating path?
How far do you mount it from the desired location where you are pinpointing temperature measurment?
While I would agree that a Non contact passive infrared rules..........
I would like to some day compare the accuracy of the $20 passive infrared with
the K type thermocouple and a simple thermistor.
Noting that my ROYAL laminator heater control was done by a contact thermistor clamped to the aluminum heat shield
behind a roller heater.
When I was looking into thermocouple circuits and supporting chips it looked like about $15 gets that done
and
5 cents buys a thermistor....
or maybe a dollar if it has wires.
New Reprap NTC 3950 Thermistor 100K with 1 Meter wire for 3D Printer TSCA
Non contact passive infrared rules...
Get one of these...
https://www.sparkfun.com/products/9570