How to choose a blackbody or Infrared temperature calibrator
What is “Distance-to-Spot” (D:S) Ratio of Infrared Thermometer? - UNI-T Meters | Test & Measurement Tools and Solutions
The "Spot Size" of the Measurement
Amazon.com: ROKTEK T2500 Infrared Thermometer, Non-Contact Digital Temperature Thermometer -58 to 716°F (-50 to 380°C), 12:1 Distance to Spot, Standard Size, Black, Backlit Display : Industrial & Scientific
About Infrared (IR) Thermometers: Distance to Spot Ratio – Sper Scientific Direct
Amazon.com: Performance Tool W89721 Non-Contact Digital Laser Infrared Thermometer, Orange and Black With 12:1 Spot Ratio : Industrial & Scientific
Steps to determine if the size of your source is too small
How to Get Great Results with an Infrared Thermometer | Fluke
Fluke Electronics Fluke 62 MAX IP54 Infrared Thermometer, -30C to 500C & 101 Distance to Spot Size Ratio 5065894 | Zoro
Science, Technology and Society - An authentic exploration on IR thermometers application in schools
Temperature Measurement Strategies | 2011-11-01 | Process Heating