There is difference between radiation pyrometer and optical pyrometer is given below.
| Radiation pyrometer | Optical pyrometer |
|---|---|
| Temperature is direct measured with the help of thermocouple. | Temperature is measured by comparing the brightness of hot body radiation at specific colour. |
| Emissivity of target may affect measurement. | Dust, smoke and thermal background radiation affect. |
| Chance of error is negligible. | Causing human error. |
| The radiation pyrometer has moderate cost. | The optical pyrometer has high cost. |
| The output is directly given by thermocouple in terms of m volt. | The output is observed by human eye. |