Measuring Turbine Speed
A previous PHILTEC Application 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 wanted to measure turbine speed by sensing the passage of 1 mm thick blades.
1-mm thick turbine blade
Access to the blades could only be made at a 50° angle to the blade tip surface. And, PHILTEC engineers were not sure if the blade could be sensed at that angle.
A 1.5-mm diameter test probe was constructed with the fibers polished to a 30° angle. When the fibers were illuminated, the emitted light beam filled a 50° cone.
50° Light Beam
A 1-mm blade was placed on a linear stage and mounted at 30° and 50° angles to the test probe.
Probe mounted at 30° and 50° angles to linear stage
The probe output was recorded as the blade moved past the light beam of the probe.
30° Angle: Max/Min = 9 ….. 50° Angle: Max/Min = 4.4
Graphs of probe detecting turbine speed
Angle polished probes can detect turbine blade passage up to a 50° access angle.
Philtec Inc. is a manufacturer of custom fiber optic displacement sensor systems. Based in Annapolis, Maryland, Philtec has been providing innovative sensing solutions since 1988. Their sensors are built in the USA and sold worldwide. Their engineers can help you design special sensors uniquely meeting your requirements. Applications for Philtec’s sensors include:
- Computer printers and hard drives
- Oil well drilling
- Medical equipment
- Motion control
To request more information or a quotation for Philtec products, contact IL Photonics.