Deposition tube temperature is critical, which means your process pyrometer must be calibrated. To ensure accuracy, I use a handheld calibration standard that is independent of the process pyrometer. Look through the pyrometer viewfinder, moving through the hot zone until the maximum temperature is detected. This maximum temperature is the actual temperature. Compare this reading to the process pyrometer and check for calibration shifts. You do not need to purchase an expensive blackbody unit. Instead, purchase a hand-held standard that is calibrated with a blackbody standard. In addition, you could temporarily mount the hand-held pyrometer on the fire carriage to spot-check the process pyrometer calibration. Read more: “Critical Design Goals to Manufacture Optical Fiber Preforms.”


Additional resources from the FOC team include:

Have questions about this FOC Tip?

Contact FOC with questions at: (800) 473-4237 / 508-992-6464 or email: and we will respond ASAP. 

Additional articles from our preform fabrication consultant include:

FOC Technical Experts

About FOC Technical Experts

Fiber Optic Center has a team of cable assembly experts with decades of years of technical experience in the field. This team contributes to the FOC blog articles, technical tips, product videos and FAQs.