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Turbine Speed Probes

By on February 10, 2023 in Fiberoptic Sensors, Non-Contact Sensing, turbine speed probes

The previous App Note ‘Bending Light’ showed that the light beam emitted from a fiber optic probe can be redirected to a different emission angle by polishing the fibers at an angle to the probe axis.

A new customer wants to measure turbine speed by sensing the passage of 1 mm thick blades.

THE PROBLEM: Access to the blades can only be made at a 50° angle to the blade tip surface. And, we’re not sure if the blade can be sensed at that angle

Probe Install at 50°

TEST PROBE

A 1.5 mm diameter test probe was made with the fibers polished to a 30° angle. When the fibers were illuminated, the emitted light beam filled a 50° cone.

50° Light Beam

TEST SETUP

A 1 mm blade was placed on a linear stage and mounted at 30° and 50° angles to the test probe.

1 mm Blade

The probe output was recorded as the blade moved past the light beam of the probe.

RESULTS

30° Angle : Max/Min = 9 ….. 50° Angle : Max/Min = 4.4

CONCLUSION

Angle polished probes can detect turbine blade passage up to a 50° access angle.

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2 TESLA EXPOSURE

By on April 23, 2020 in 90° Probes, connectors, Displacement Sensor, Fiberoptic Sensors, Magnetic Fields, Non-Contact Sensing, Right Angle Probes

Magnetic Field Exposure requires non-magnetic materials. By jacketing the fiberoptic cable in non-metallic materials, and by constructing the sensor tip from non-metallic or non-magnetic materials, Philtec sensors can be configured to perform measurements in very high magnetic fields. Successful applications to 12 Tesla have been made.

We recently delivered this sensor; a model D20 high-frequency sensor for 2 Tesla exposure.

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Long Length Fiberoptic Cables

By on February 5, 2020 in 90° Probes, Displacement Sensor, Fiber Optic Vacuum Passthru, Fiberoptic Sensors, Magnetic Fields, Non-Contact Sensing, Quartz Fibers

PROBLEM
Quartz fibers have excellent transmission over long lengths, but they are very expensive and usually cost prohibitive. A recent customer asked for a model D171 sensor with 45 meter length for displacement measurements in vacuum and high magnetic field.

SOLUTION
A 3-piece cost saving system was devised where only nineteen 200µm quartz fibers were used to illuminate 10% of the model D171 probe area.
Part A – Two Ø 1000 µm Hard Clad Silica Fibers, 20 m long in air
Part B – Two Ø 1000 µm Bundles of Ø 200µm Silica/Silica (Quartz) Fibers, 24.5m long in vacuum
Part C – Ø 4320 µm D171 Glass Fibers, 0.5 m long in Vacuum

Part A has two Ø1000µm fibers at the connector interface:

1000 µm HCS Fiber

Part B Ø1000 µm fiber bundles each have 19 fibers at the connector interface:

one transmits light and one returns reflected light.

Part B transmit fibers were randomly mixed with Part C glass fibers. Although Part B fibers illuminated just 10% of Part C fibers, this D171 sensor calibrated to an acceptable 70 mm displacement range. And therefore, the system cost was much lower than it would otherwise have been if all of the D171 fibers had been illuminated by quartz fibers.

Model D171 has several thousand 50µm glass fibers in a 4320µm diameter bundle.
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Sensors for Space Telescope Lens Testing

By on May 23, 2019 in Cryogenic environments, Displacement Sensor, Fiber Optic Vacuum Passthru, Fiberoptic Sensors, multiplexing sensors, Non-Contact Sensing, Quality Control, space cryogenics, Space Telescope Lens

The Euclid Satellite project a good example of Philtec’s sensors being used with excellent results in cryogenic conditions. A technical paper published in 2012  shows Philtec’s high precision sensors were successfully used at 150°K to verify the distortion of lens holders to be <1 micron,  well within the project requirements.

This month Philtec has again delivered sensor systems for space telescope lens distortion measurements. These are 2-channel fiber optic displacement sensor systems designed for 3.2 mm operation in vacuum.

2-Channel Displacement Sensor with BvF120 Vacuum Passthru Assembly

Seven 2-channel sensor systems were delivered with the following options:

  • Multi-Channel Vacuum Passthru Assembly in 120 mm Custom Flange
  • SS Interlok Cable Jacket in Vacuum
  • 6m Total Fiberoptic Cable Length (1.5 in air, 4.5 in vacuum)
  • Low CTE Invar Tips

The fiber optic cables are trifurcated for connection to the vacuum passthru (one transmit bundle and two receivers). With 14 sensor channels x 3 legs each, 42 vacuum ports were required. Each BvF120 has 16 ports, and therefore three BvF120 assemblies were used to pass all channels.

Multi-Channel Vacuum Passthru Assembly

REFERENCE

‘Test Results of High-Precision Large Cryogenic Lens Holders’, 2012, Proceedings of the SPIE Publication “Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II”.

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Measuring Embedded Objects

By on April 4, 2019 in 90° Probes, Displacement Sensor, Fiberoptic Sensors, Miniaturized Sensors, Non-Contact Sensing, Right Angle Probes

Tiny 90° Probes

Philtec specializes in the design of sensor systems for gaining access to hard to reach targets. In March 2019, several dozen model D47 sensors were delivered with long fiber optic cables and very small 90° probes as seen here. The fiber optic cable lengths varied from 21 ft. to 55 Ft. long

D47 2-PART SENSOR SYSTEM

D47 3-PART SENSOR SYSTEM

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Custom Probes

By on March 26, 2019 in 90° Probes, Aerospace, Displacement Sensor, Fiberoptic Sensors, High pressure environments, High Temperature, Magnetic Fields, Measurements in fluids, Miniaturized Sensors, Non-Contact Sensing, Right Angle Probes
Special Probes Made To Customer Requirements

Send us a sketch or drawing of your application requirements. We’ll make a sensor configuration drawing for your review. Email sensors@philtec.com

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Probes for Cryogenic Turbo Pumps

By on December 11, 2018 in Aerospace, Cryogenic environments, cryogenic turbopumps, Fiberoptic Sensors, High pressure environments, Liquid Oxygen, Non-Contact Sensing, space cryogenics, Space Launch Vehicles, Uncategorized

Philtec builds custom displacement sensor systems to meet application requirements, which often include extreme environments. This month we delivered 8 sensors having 200 KHz bandwidth (sensor speed). The probe tips are threaded and connectorized so they may be separated from the sensor electronics.

Probes are Connectorized to the Electronic Modules 
Probe Tips are Immersed in LOX at -300°F and 1,000 psi
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1000°F Application

By on December 6, 2018 in 90° Probes, Displacement Sensor, High Temperature, Hot Targets, Non-Contact Sensing, Right Angle Probes, Uncategorized

CUSTOMER FEEDBACK

“I wanted to let you know the sensors worked as designed during our tests.  I may follow up with Chris on a few specific questions as we begin to sift through all of our data.  Thank you again for your professionalism and for all your support.” … Sincerely, VMR, Mechanical Engineer

THE APPLICATION

Five special right angle probes were delivered for a 1000°F tip exposure test.

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High Pressure Applications

By on May 4, 2018 in Fiberoptic Sensors, High pressure environments, Non-Contact Sensing

There are three options for sealing the leak path thru the fibers under pressure:

1. Epoxy filled tips

2. Sapphire Windows epoxied into tip counterbores

3. Sapphire Windows brazed into tip counterbores

The best solution for an application depends upon several factors such as: the size of the fiber bundle, the dimensions of the probe tip, as well as the amount of applied pressure. Pressure can be static, reciprocating or pulsing. Extreme temperatures can be coupled with high pressures, and the probes could be submerged in oils or cryogenic fluids. Effectiveness of the seal and cost are major considerations. Philtec engineers can assist with the choice and design of the probe.

Design Guidance

Pressurized Cryogenic Fluids

Example: High Pressure Application

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ROCKET ENGINES for SPACE LAUNCH VEHICLES

By on April 3, 2018 in Cryogenic environments, cryogenic turbopumps, Fiberoptic Sensors, High pressure environments, Measurements in fluids, Non-Contact Sensing, Rotor Dynamics, Space Launch Vehicles

A new generation of LOX/Methane engines are under development, and many have used Philtec’s FODS (Fiber Optic Displacement Sensors) for rotor dynamics measurements in the testing phase. Fiber optic probes are an ideal sensor choice in these applications where they are exposed to pressurized cryogenic fluids.

In 2016-2017, 100 sensors are delivered to companies testing advanced turbopump designs.

READ MORE

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