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FOCIS™ Optical Probes

Prime Photonics manufactures the widest selection of optical sensors available today for high temperature applications such as optical blade tip timing, optical clearance measurement, or rotor and shaft speed sensing.

FOCIS™ probes are operational in high temperature environments.  They are a superior option for vibratory stress analysis using non-intrusive stress measurement system (NSMS) techniques.

Unlensed Probes

FOCIS™ unlensed sensors are optical probes used for non-contact blade vibration measurements on rotor blades and blisks/IBRs, flutter detection, crack and damage detection, and speed measurement.  Some of our unlensed probes can withstand temperatures up to 700 deg C (1300 F) uncooled.

Standard Unlensed Optical Probe for Blade Tip Timing
Picture Above: Unlensed Probe

Our optical sensors typically consist of a metal capillary tube rated for high temperatures, followed by a flexible cable and a splitter which goes to the send and receive connectors.

Most optical probes are custom developed.  Customers can specify any parameters of the probe such as length of each section, diameter of the metal hypodermic tube, temperature rating, custom flanges, number and size of optical fibers, etc.  Prime Photonics can also design probes based on application requirements.

Unlensed Probes Data Sheet (pdf)

For a much wider selection of probes, as well as for custom probes, please Contact Us directly.


Lensed Probes

Lensed sensors are superior optical probes which use a lens to focus the light beam.  They are primarily used to provide all optical measurement of casing-to-rotor blade tip clearance and can be configured to make displacement measurements in many other rotating equipment applications.  They can withstand prolonged exposure to 590 deg C (1100 F) uncooled.  Higher temperatures are possible with cooled probes which feature internal cooling channels.

Optical Sensor For Blade Tip Timing and Blade Tip Clearance
Picture Above: Standard Lensed Probe

Lensed Probes Data Sheet (pdf)


Low Profile, Right Angle Probes

Right angle probes are designed for installation in tight spaces with very little space above the probe head for installation and removal.  They consist of a short head and a hard line exiting the head at a 90 degree angle.

Right Angle Probe
Picture Above: Right Angle Probe

Right Angle Probes Data Sheet (pdf)


Periscope Probes

Periscope probes are inserted in the gas path, downstream or upstream of blades, and pointed at the trailing edge or at the leading edge of the blades.  These optical sensors allow measurement of tip timing on shrouded blades and other conditions which prevent access to the tip of each blade.

Periscope probe principle and picture
Picture Above: Periscope Probe

Periscope Probes Data Sheet (pdf)


Beam Breakers

Beam breakers work as a pitch / catch arrangement with two separate probes, one for sending the optical signal and one for receiving the signal.

Beam Breaker Data Sheet (pdf)


Advantages of FOCIS™ Optical Sensors

Advantages of FOCIS™ tip timing & clearance probes include:

  • High temperature
  • Immune to electrical noise or EMI
  • Clean signal from FOCIS™ SIU that requires minimum signal processing
  • Pulse width insensitive
  • Small engine casing penetration, typically 6.35 mm (1/4 inch) diameter for lensed probes and as small as 1.6 mm (.06 inch) diameter for unlensed probes
  • High spatial resolution of lensed probe design
  • Robust windowed probe face allows for cleaning and re-use of probes
  • Compatible with both metallic and non-metallic blades
  • Self-compensating for variations in engine speed
  • Resolution vs. range configurable
  • High resolution

When coupled with Prime Photonics Instrumentation (Sensor Interface Unit):

  • Allows resampling of data to nearly uniform phase angle
  • Automatic noise reduction at lower speeds through sample aggregation
  • Hunting:  When confidence is low, rapidly adjust timing to find blade frequency
  • Typically achieves lock within the first 20 blades
  • Will maintain lock with blade passing frequency changes of up to 33% per blade


Custom Probes

Prime Photonics offers a variety of standard probes for the most typical applications, but most probes must be customized.  Whether simply adding a custom flange or designing an entirely new probe, Prime Photonics offers complete design and manufacturing capabilities to each customer's specifications.

The following parameters are important when contacting Prime Photonics for a custom probe:

  • Temperature: maximum temperature of the probe
  • Cable type: rigid or flexible cable exiting the probe head.  A combination of rigid and flexible is available.
  • Cable length and diameter
  • Connectors: FC, ST, and SMA connectors are standard.  We can accommodate custom requests for other connector types.
  • Purge gas option: optional purge gas fitting for probe cooling or cleaning is available

Prime Photonics also provides specialty manufacturing services for customer-designed probes.  Our extensive knowledge of probe design for high temperatures allows us to provide feedback and recommend improvement to customer designs as necessary.  Our ISO9001 certification ensures the highest standards in probe quality through rigorous manufacturing processes and thorough checkout testing.


More Information

For more information, comments, questions, or to request a price quotation please use the contact form below.

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