That's an intermediate level project that sounds fun, but you don't need anything as complex as a Raspberry Pi. A simple microcontroller like an Arduino Nano would work great and cost less. Remember, a Raspberry Pi is an entire, albeit simple, computer. Arduino is a much simpler (and cheaper) microcontroller. (There's some overlap in capabilities, so take this as a reasonable generalization.)
Here's a sample project for non-contact temperature sensing:
Also, this book is an excellent resource for Arduino. It was just updated. https://www.amazon.com/dp/1680456938?ref=ppx_pop_mob_ap_share