FBG-based temperature sensors OSHT series (up to +500ºС)


Fiber optic high-temperature sensors (OSHT) based on fiber Bragg gratings (FBG) provide reliable long-term measurements of gases, liquids and solids up to temperature of 500°C.

Bodies of OSHT sensors are made of structural cryogenic austenitic stainless steel 316L, resistant to corrosion in corrosive environments. Stainless steel tube is used for mechanical protection of connecting fibers in OSHT sensor type.

OSHT-311 sensors having flat metal body are designed to measure surface temperature and can be used as single (end type) or multiple (several sensors in one fiber) configuration. Probe-type OSHT-313 sensor is manufactured in the form of a metal cylindrical tube, which makes it possible to use the sensor in industrial equipment as an easy alternative to standard electrical thermometers.

Design of OSHT sensors can be adapted to the Customer requirements while maintaining their functionality.

The spectral shift of the resonant wavelength of the FBG sensor can be recorded by any FBG interrogator. For this purpose, our company offers a line of interrogators - unified recording modules (URM) - that provide acquisition and processing of spectral information of FBG sensors with subsequent output of the results to the operator.

The FORC-Photonics OSHT sensors have the following advantages:

  • spectral multiplexing;
  • possibility of remote measurements (no power supply requires at the measurement site);
  • long-term stability of measurements;
  • immunity to electromagnetic interference;
  • fire safety;
  • small dimensions and weight;
  • wide temperature range of measurements;
  • low error level within the entire measurement range.


Local and quasi-distributed thermal monitoring of objects, structures and systems in various fields of science and technology:

  • buildings, roads, bridges and other constructions;
  • hydro, wind, nuclear power stations;
  • cars, railway and sea transportation;
  • airplanes and space systems;
  • oil and gas industries, including pipeline monitoring.


  • high temperature measurements (up to 500°C).
  • high accuracy and long-term stability
  • fast response time
  • ease of installation using standard fittings
  • robust and high-temperature performance of the fiber cables
  • high calibration accuracy and the use of simple calibration equations, allowing measurements using most FBG interrogators.



Волоконно-оптические высокотемпературные датчики (OSHT) на основе волоконных брэгговских решеток (ВБР) Волоконно-оптические высокотемпературные датчики (OSHT) на основе волоконных брэгговских решеток (ВБР)
OSHT-311 OSHT-313





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Thermal characteristics
Operating temperature range,  ºС +500
Absolute accuracy, ºС ± 2,5 ± 1,5 ± 1,5
Cable operation temperature range,  ºС +500 -
Connector operation temperature range,  ºС  -40 ÷ +80
Temperature constant, s 1.5 4.5 7
Temperature sensitivity, ppm/ºС 22 ÷ 24 6.5 ... 10.5 7 ... 11
Optical characteristics
Resonance wavelength, nm 1510 ÷ 1590
Peak reflectivity, %  60
FWHM, nm 0.3 ÷ 0.4
Fiber type compatible with SMF-28
Connector type (on request) without connector, FC/APC, LC/APC, SC/APC
Mechanical characteristics
Sensor body size, mm 15 х 15 х 1.1 15 х 15 х 1.1 Ø 21 x 195
Probe diameter, mm - - Ø 4
Sensor connecting size - - М20х1.5
Probe length (on request), mm - - 200*
Attachment method contact welding contact welding threaded connection
Sensor body material SS 316L
Optical fiber protection material SS 316L -
Cable length, m 1 (both side) 1 -

*- at the request of the customer can be changed from 200 to 1000mm

FBG - based temperature sensors OSHT series (up to +500ºС)