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      Plugin: PhotonFirst FBG Interrogator (GInsPhotonFirstPlugin)

      The GInsPhotonFirst plugin can read measurement data from PhotonFirst's fiber Bragg grating (FBG) interrogators, enabling the integration of fiber-optic sensors with electrical sensors into a single data acquisition system.

      Introduction

      PhotonFirst uses advanced technology by sending light into an optical fiber and capturing it with sensors that reflect the light like a mirror. The reflected light is then analyzed, and the difference between the emitted and reflected light is translated into measurement values such as temperature, strain, pressure, or shape. This process is facilitated by the photonics integrated circuit (PIC).

      PhotonFirst has a range of FBG interrogation systems. The plugin currently supports two interrogators:

      1. The GTR FBG Interrogator is a single-channel fiber Bragg grating interrogator that offers 1 pm precision and high-speed sampling capabilities. It is a compact, out-of-the-box platform designed to support a wide range of applications and environments.
      2. The SGTR Multichannel FBG Interrogator is an eight-channel Bragg grating interrogator that offers fast channel multiplexing, high-resolution sensing, and high sampling rates per channel. With its unique feature set and compact size, weight, and power specifications, the SGTR represents an excellent solution for FBG interrogation applications.

      Minimum system requirements

      The minimum system requirements for this plugin are:

      • Q.station 101 / Q.station X
      • Q.station firmware V2.18.3

      Plugin installation

      General workflow for configuring the plugin

      In general, the plugin writes the data received from the interrogator to an additional datastream on the Q.station controller. A web interface is provided for configuring the plugin.

      1. On the controller create an Additional datastream.



      2. The following variables from the interrogator can be included in the datastream. If the variable names follow the below naming convention, the mapping of the interrogator variables is done automatically when clicking Save in the plugin web interface.

        • SensVal-XY: Sensor data, where X = channel no. [1-8] and Y is sensor no. [1-8].

        • SensCnt-X: Number of sensors detected in a channel, where X = channel no. [1-8].

        • SensState-X: State of sensors in a channel, where X = channel no. [1-8]. 

        • MsgTime: Timestamp of message.

        • MsgCnt: Counter of message.

        • MsgSwState: Position of optical switch [0-7].

      3. To access the web interface, open a web browser and enter http://[ipaddress]:8090/GInsPhotonFirstPlugin, where [ipaddress] represents the IP address of the controller.


      Configuring a connection

      Commands

      • Save: Saves all settings.

      • Set default: Resets the complete plugin to its default settings, deleting all settings.

      General Settings

      • Dev path: The USB port on the controller to which the interrogator is connected.

      • Interrogator: Select the interrogator model, either the GTR single-channel interrogator (GTR-1001) or the SGTR multichannel interrogator (SGTR-1001).

      • Sampling frequency: The sampling rate configured for the interrogator.

      • Stream: The additional data stream on the controller where the data will be written.

      Ensure that the source cycle frequency of the additional stream, the interrogator sample rate, and the plugin settings are all configured to the same sampling rate.

      Switch Config

      • Viewing time in ms: [SGTR interrogator only] Time spent reading each channel before switching to the next. The default setting is 50 milliseconds.

      Stream Config

      In the Stream Config section, the individual channel(s) and sensor mappings to the data stream and process image (via virtual variables) can be configured.

      • Unit conversion:

        • CoG [Center of Gravity]: The absolute, calibrated central wavelength value.

        • Wavelength [nm]: The CoG value converted to actual wavelength value.

        • Microstrain [µε]: The CoG value converted to microstrain.

        • Temperature [°C]: The CoG value converted to temperature.

      • Thermo expansion coefficient: The coefficient of thermal expansion (≈5.2·10⁻⁷ for silica), used to convert the measured wavelength to temperature for this channel.

      • Thermo optic coefficient: The thermo-optic coefficient (≈5–10·10⁻⁶ °C for silica), used to convert the measured wavelength to temperature for this channel.

      • Additional data stream: Select the stream variables to which the sensor data should be mapped. If the default naming convention is used, the mapping will be done automatically.

      • Process image: Select the virtual variable (also known as process image variables) to which the sensor data should be mapped. If the default naming convention is used, the mapping will be done automatically.

      • Central wave length: The known central wavelength of the sensor (λ₀), required for accurate temperature measurements.