# Binomial Fitting Formulas

**URL:** <https://forum.ofscn.net/t/binomial-fitting-formulas/291>\
**Category:** OFSCN Technical Knowledge Base\
**Tags:** fbg-technology, wiki-fbg-tech, fbg-temp-sensor, high-temp-cable\
**Created:** [January 21, 2026, 12:54pm UTC](https://forum.ofscn.net/t/binomial-fitting-formulas/291 "2026-01-21T12:54:13Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![frostweaver](https://forum.ofscn.net/letter_avatar_proxy/v4/letter/f/da6949/32.png) [@frostweaver](https://forum.ofscn.net/u/frostweaver)\
**Post date:** [January 21, 2026, 12:54pm UTC](https://forum.ofscn.net/t/binomial-fitting-formulas/291/1 "2026-01-21T12:54:13Z")

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Why does OFSCN® recommend using binomial (quadratic) rather than linear formulas for temperature calculation?

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<div class="post-metadata">

**Author:** ![OFSCN\_Tech\_Expert](https://forum.ofscn.net/user_avatar/forum.ofscn.net/ofscn_tech_expert/32/199_2.png) [@OFSCN\_Tech\_Expert](https://forum.ofscn.net/u/OFSCN_Tech_Expert)\
**Post date:** [January 21, 2026, 12:54pm UTC](https://forum.ofscn.net/t/binomial-fitting-formulas/291/2 "2026-01-21T12:54:18Z")

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The wavelength-temperature response of an FBG is not perfectly linear across a broad temperature range. A binomial (quadratic) fitting formula offers a more accurate representation of this relationship compared to a linear formula because it accounts for the higher-order non-linearities in the material properties (such as the thermo-optic coefficient and thermal expansion coefficient) as they change with temperature. This allows for more precise temperature measurements over the full operating range of the sensor.

Here is an example of an OFSCN® FBG Temperature Sensor:

 ![OFSCN® 300°C Fiber Bragg Grating Temperature Sensor](https://forum.ofscn.net/uploads/default/original/1X/74932c0f3b71797adb12ca84a053059151051842.jpeg)  
 ![OFSCN® 300°C Fiber Bragg Grating Temperature Sensor](https://forum.ofscn.net/uploads/default/original/1X/890e8bb137088d916b6145a3bd3543febc968fd1.jpeg)

You can find more details on our [OFSCN® 300°C Fiber Bragg Grating Temperature Sensor](https://www.ofscn.net/fbg-products/temperature-sensor-300.html) product page.