Sengenia
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Introductory Video
What are Fibre Optic Sensors? Click the image below for an introductory video

Contact Info
Sengenia contact info
Sengenia Ltd
5 Kensington Court,
Dollingstown,
BT66 7HU
N. Ireland

Tel: +44 (0)7515 85 19 18
Email: sales@sengenia.com


Frequently Asked Questions

Welcome to the frequently asked questions page for Sengenia. We hope that you’ll find an answer to your enquiry here but if not please don’t hesitate to contact us via any of the means listed on our contacts page. The page is divided into 3 sections:

Sensors:

Q: What is the maximum distance that there should be between the sensor and the interrogation system?
Q: What can you tell me about using the FBGs in cryogenic conditions?
Q: What conditions are used for the temperature calibrations?
Q: What is the primary coating of the fibre used for the 120 degree and 275 degree versions of the os4310?
Q: The gratings provided, are they draw tower produced?
Q: Do you know if the sensor metal base could be bent (e.g. os3120)?
Q: Is the fibre in the groove bonded or pre-stressed for the packaged sensors?
Q: What temperature sensor would you recommend for higher pressure environments?
Q: Are there any issues to using the sensors for monitoring marine turbines?

Filters:

Q: What is the max input power for FFP-TF2 having 10000 finesse?
Q: Could you clarify if your FFP filters reflect the light back at the wavelengths being out of the filter bandwidth or not? If your filter is just a usual Fabry-Perot interferometer, it should reflect the light back, am I right?
Q: Can we tune wavelength and keep the FSR, i.e. we just shift the peaks, or the tuning changes the FSR only i.e. the peak spacing is varied?
Q: Do you have a 400 GHz filter(any type)?
Q: I’m interested in the FFP-TF and wondering if Micron Optics can offer pigtailing the filters with PMF on input and output?

Interrogation systems:

Q: Which unit would be suitable for Fabry Perot sensor interrogation?
Q: I would like to create and use my own peak detection method in Labview software, which unit would you recommend?
Q: What does the “x25” and “x30” mean in the unit names?
Q: What does the “sm” and “si” mean in the unit names?
Q: What does the “1” stand for then on the sm125 units?
Q: I'm trying to find out what the output power is from the source to do some power budget investigations and the manual states under the laser safety section that the output is 0.25mW max, is this the correct value I should use in my analysis?
Q: Are the si920 and si325 units still available?
Q: I’d like to customize the front end of the interface to the interrogator. From the manual it appears I can interface with LabView but wondered if there is provision for me to write an application in something like C# (.net) and send commands to the interrogator?
Q: Can any Ethernet cable be used with the units?
Q: Is there a simple way that I can view the IP address?
Q: I’m having issues getting my PC to connect to my sm125?
Q: I need a unit with <10W power consumption, do you have anything that might meet this?
Q: Is ENLIGHT Mac compatible?
Q: Would the instruments listed below each be able to simultaneously interrogate the FBG/EFPI: Sm130-500, Sm130-700, Si730-500?






Sensors:

Q: What is the maximum distance that there should be between the sensor and the interrogation system?
A: The maximum distance from the interrogation system to the sensors is dependent on the loss of your fibre cable. A typical cable loss is estimated to be 0.5dB/km loss, two way.

Q: What can you tell me about using the FBGs in cryogenic conditions?
A: In general, cryogenic temperature sensing using FBGs is possible and has been done by various groups. For cryogenic strain sensing by far the most common tends to be the use of bare, polyimide coated fibres mounted on the specimens of interest. In this sense, the grating will measure both the strain and temperature, except that - depending on the cryo temperature - the expected strain and temperature wavelength shift coefficients will tend to be different that those normally used at room temperature. Our os3100 will not work at cryo, because of the pre-stretch. However, our os3200 should be fine, except that the appropriate low temperature epoxy must be used. So, in a nut shell, use os1100s or os3200s with polyimide coating and use suitable epoxies.


Q: What conditions are used for the temperature calibrations?
A: We use our Hart temperature readouts and probes for calibrating our temperature sensors. They are calibrated (as a pair) once per year to a NIST traceable standard through a local calibration company.


Q: What is the primary coating of the fibre used for the 120 degree and 275 degree versions of the os4310?
A: Both versions use polyimide coating


Q: The gratings provided, are they draw tower produced?
A: No


Q: Do you know if the sensor metal base could be bent (e.g. os3120)?
A: No. These sensors are designed for flat surfaces. It would make the measurement unreliable and the calibration constants would change. You might want to try using the os3200 sensor for a curved surface. It is non-metallic and is designed to apply an even amount of epoxy around the FBG and to the surface you want to monitor.


Q: Is the fibre in the groove bonded or pre-stressed for the packaged sensors?
A: The fibre is pre-stressed and then bonded between two points on the metal base.


Q: What temperature sensor would you recommend for higher pressure environments?
A: The most important factor with the different pressures is the compression fitting seal on the stainless steel housing of the temperature sensor. We have never really reached a pressure ceiling, so they haven’t necessarily been certified for use in specific environments. Our engineers recommended the os4230 and os4280 as this is a rugged probe in stainless steel housing about 3/16” and 1/4" wide.


Q: Are there any issues to using the sensors for monitoring marine turbines?
A: So long as proper waterproofing of the carrier and cable are taken into consideration, there shouldn’t be any major obstacles.

Filters:


Q: What is the max input power for FFP-TF2 having 10000 finesse?
A: The maximum input power is based on various experimental input. There is no rigorous theoretical basis for our numbers. The key parameter is the intra-cavity re-circulating power, which is the input average power divided by the mirror transmission. Often we have ~20W of intra-cavity re-circulating power in our swept lasers. So for a mirror R~99.9% (T~0.001) the average input power is ~20mW.


Q: Could you clarify if your FFP filters reflect the light back at the wavelengths being out of the filter bandwidth or not? If your filter is just a usual Fabry-Perot interferometer, it should reflect the light back, am I right?
A: Correct, all wavelengths that make it through the transmission window are reflected.


Q: Can we tune wavelength and keep the FSR, i.e. we just shift the peaks, or the tuning changes the FSR only i.e. the peak spacing is varied?
A: The FSR is maintained while tuning the filter. The mirror ferrules within the filter are held in place with PZT. For the FFP-TF, increasing the voltage to the PZT forces the mirrors apart and lengthens the etalon cavity therefore moving the peaks towards longer wavelengths. More technical information can be found under the general overview section of the Tunable Filter Document Library on the Micron Optics website.


Q: Do you have a 400 GHz filter(any type)?
A: A 400GHz can be achieved with both the FFP-I and FFP-TF2.


Q: I’m interested in the FFP-TF and wondering if Micron Optics can offer pigtailing the filters with PMF on input and output?
A: It may be possible, but it adds a considerable cost to use PMF.

Interrogation systems:


Q: Which unit would be suitable for Fabry Perot sensor interrogation?
A: The unit suitable for Fabry Perot sensor interrogation is the sm125. Since it has a 50dB range it has more sampling resolution.


Q: I would like to create and use my own peak detection method in Labview software, which unit would you recommend?
A: The sm125 is the recommended interrogator to use if you are creating your own LabView peak detection. The sm130 uses analog peak detection that uses zero crossing techniques. Additional routines would slow down the sm130.


Q: What does the “x25” and “x30” mean in the unit names?
A: Each MOI instrument is based on one of two basic optical cores: static or dynamic. The static core is called the "x25" (as in sm125), the dynamic core is the "x30" (as in si730).


Q: What does the “sm” and “si” mean in the unit names?
A: Each interrogator is either a sensing module, "sm," or sensing instrument, "si." Sensing modules (e.g., sm125) respond to user commands for data transfer via an Ethernet connection. Sensing Instruments use Integrated ENLIGHT and Embedded XP for onboard management of the interrogator core settings, data management, sensor calibration, data visualization and data storage. User interaction is via an external keyboard/mouse/monitor or built in touch screen.


Q: What does the “1” stand for then on the sm125 units?
A: Packaging is either "1xx" for field interrogators (e.g., sm125), "2xx" for 19 inch rack mount interrogators (e.g., sm230) and "7xx" for laboratory interrogators (e.g., si730).


Q: I'm trying to find out what the output power is from the source to do some power budget investigations and the manual states under the laser safety section that the output is 0.25mW max, is this the correct value I should use in my analysis?
A: For the sm125, the power of the laser source can vary from unit to unit. We match the power of our lasers to the sensitivity of our detectors in order to achieve a combined 50dB dynamic range. The hottest laser we can ever use is 0.25mW and that is why it is specified that way in the manual. Unfortunately, we do not know what the specific output power of any one particular unit is.


Q: Are the si920 and si325 units still available?
A: No, these items are now discontinued.


Q: I’d like to customize the front end of the interface to the interrogator. From the manual it appears I can interface with LabView but wondered if there is provision for me to write an application in something like C# (.net) and send commands to the interrogator?
A: Any programming language can be used to talk to the interrogator, including C#. As long as one follows the same sort of steps, procedures and string command structure as described in the ENLIGHT manual, you should be able to communicate with the instrument. LabView would be the easiest way since we already have routines that come with the instrument and National Instruments has more routines written for our instruments available off their web site.


Q: Can any Ethernet cable be used with the units?
A: We supply crossover cables with the units as a standard Ethernet cable will not function properly.


Q: Is there a simple way that I can view the IP address?
A: You can view the IP address by booting the system when VGA monitor is connected. Then adjust the IP address accordingly. See section 5.1.1 in the user manual for more detailed information.


Q: I’m having issues getting my PC to connect to my sm125?
A: The sm125 and the host computer must be on the same logical network in order to connect. If the static IP address and IP netmask entered on the PC do not allow connection to the unit, the IP address, IP netmask or Gateway of the sm125 have most likely been changed. 255.255.255.0 is the netmask, the gateway should be 10.0.0.1.
By connecting a monitor directly to the sm125, you can access the Instrument Configurator which will show the current IP address and IP netmask settings on the sm125. Once the Instrument Configurator is open, enter the following information:
DHCP: 0
ipAddress: 10.0.0.126
ipNetmask: 255.255.255.0
Gateway: 10.0.0.1
To save new settings, click the Save & Quit button.
After both the sm125 and computer have been given the appropriate IP settings, connect a crossover Ethernet cable to the sm125 and the computer. Then open CMD.exe and Ping 10.0.0.126.
More information about IP Address Management is in section 5.1.1 (pg. 113) of the ENLIGHT manual. If you do not currently have the ENLIGHT manual available, an online version can be found here.


Q: I need a unit with <10W power consumption, do you have anything that might meet this?
A: We do not currently offer any optical interrogators with power consumption less than 10W, and future interrogator models will not be designed to meet this power specification.


Q: Is ENLIGHT Mac compatible?
A: ENLIGHT software can only be run on Windows, however, there are plenty of workarounds to have Mac OS and Windows on a single Mac machine.


Q: Would the instruments listed below each be able to simultaneously interrogate the FBG/EFPI: Sm130-500, Sm130-700, Si730-500?
A: If a lower scan rate would be acceptable, I would recommend the direction of the x25 core for simultaneous interrogation of both an FBG and EFPI. Such an application is certainly possible with the x25 while taking a few considerations into account. Do you require the EFPI and FBG to be on the same fiber? Would using two different channels on the same interrogator be acceptable (FBGs on one channel, EFPI on the other)? What is the EFPI free spectral range (how many)? The EFPI FSR should be limited by the numbers that are practical to measure.