When measuring low emissivity objects with infrared equipment, which adjustment improves accuracy?

When measuring low emissivity objects with infrared equipment, which adjustment improves accuracy?

• A. Increase distance
• B. Changing the emissivity setting
• C. Calibrate to ambient
• D. Use a different wavelength

Answer: (B)

Emissivity is how efficiently a surface emits infrared energy compared with a perfect blackbody. Low-emissivity objects, like polished metal, reflect a lot of ambient radiation, so the camera’s reading includes both what the object emits and what it reflects. If the camera’s emissivity setting doesn’t match the object's true emissivity, the calculated temperature gets biased. Adjusting the emissivity setting to match the object's actual emissivity makes the radiometric conversion correct, so the temperature reading more accurately reflects the surface itself rather than reflections. The other options don’t address this fundamental mismatch: distance changes resolution but not the radiometric bias; calibrating to ambient would skew readings toward the environment; and changing wavelength isn’t a practical fix on most field cameras.

Emissivity is how efficiently a surface emits infrared energy compared with a perfect blackbody. Low-emissivity objects, like polished metal, reflect a lot of ambient radiation, so the camera’s reading includes both what the object emits and what it reflects. If the camera’s emissivity setting doesn’t match the object's true emissivity, the calculated temperature gets biased.

Adjusting the emissivity setting to match the object's actual emissivity makes the radiometric conversion correct, so the temperature reading more accurately reflects the surface itself rather than reflections. The other options don’t address this fundamental mismatch: distance changes resolution but not the radiometric bias; calibrating to ambient would skew readings toward the environment; and changing wavelength isn’t a practical fix on most field cameras.