Interrogation monitors

Ibsen Photonics’ I-MON Interrogation Monitors set new standards for fast, real-time spectrum monitoring of FBG sensor systems.

Through a unique combination of very fast measurement frequency, low power consumption and compact size, they are ideally suited for a broad range of applications. The I-MONs offer straightforward integration and meet industrial qualification standards.


The FBG sensor is a short piece of optical fiber with a periodic modulation of the refractive index in the optical fiber.

The periodic modulation of refractive index is generated by the interference pattern created from the phase mask, and it creates a narrow filter response with peak reflectivity at a wavelength determined by the period of the FBG.

A broadband source such as a super luminescent diode (SLED) or an amplified spontaneous emission (ASE) source can be used as light source for the FBG sensing system.

When the FBG is mounted on a structure, it may be stretched or compressed due to structural changes of the structure. This causes a change in the FBG period, and the peak reflectivity of the FBG is shifted accordingly to λi+Δλ. Each fiber can contain a multitude of FBG sensors all having different peak reflection wavelength.

Determining the peak reflection wavelength and shift in peak wavelength is the basis of FBG sensing, since measurement of the reflected wavelength can be converted to parameters such as strain, pressure, vibration and temperature. The I-MON Interrogation Monitors are designed to measure the reflection spectra from the FGB sensors, and will provide data to the control electronics or PC for peak determination.


The compact size and simple electronics interface makes the I-MON Interrogation Monitors ideal for direct mounting on the customer’s interrogation system control PCB.

The I-MON series has the following features:

  • Fast measurement frequency

  • Compact size

  • Low power consumption

  • No moving parts

  • Environmentally stable fused silica gratings


FBG sensing:

  • Vibration analysis

  • Temperature measurements

  • Pressure monitoring

  • Strain measurements

Interrogation monitor platforms

We offer our I-MONs in 4 different series. Below you can find help to identify which of our I-MON series that best suits your needs. Each series can be provided in different wavelength ranges, 1550 nm as the most common, 1310 nm and 835 nm. In addition, we offer a broadband light source with built-in circulator and USB control for plug-and-play operation.



The I-MON OEM series is compact, light weight and cost efficient, and is ideal for customers who want full control of all electronics and software, as the customer interfaces directly to the I-MON diode array.

A Developer’s Kit is available to get started-plug-and-play.



The I-MON USB series is high performing, fast and rugged, and comes with USB interface and software for plug-and-play operation. It is well-suited for both industrial-grade applications and lab-type experiments in combination with a customer selected light source. LabVIEW based software allows customization and simple interfacing with other test equipment. DLL and drivers are provided for further customization.

I-MON High Speed


The I-MON High Speed series allows full spectrum measurements up to 35 kHz, while maintaining sub-picometer wavelength fit resolution. It is rugged, making it well suited for both industrial-grade applications and lab-type experiments in combination with a customer selected light source. It comes with GigE interface and software for plug-and-play operation. LabVIEW based software allows customization and simple interfacing with light sources and other test equipment.



The I-MON DISB is provided with DISB electronics that converts the analog video output from the detector to a 16-bit digital signal that can be read over SPI interface. It is ideal for customers who want a robust and reliable industrial interface to the I-MON, software, and hardware trigger control, on-board averaging, region of interest, and advanced lamp control.

Want to know more?

For further information see below.

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