D Type Fibre Optic Displacement Sensor


D models (Reflectance Dependent) are used for single axis vibration and stroking motions, where the target reflectivity is constant.
The output voltage function for D model sensors includes a near side region where the voltage rises with increasing distance, an optical peak region, and a far side region where the voltage output decreases with increasing distance. Operation in the near side region gives high sensitivity with limited operating range. Operation in the far side region gives moderate sensitivity with greater operating range.

Contact Our Sales Team

Contact our sales team via email regarding this product

Email Us
Send an Enquiry

Use our contact page to send us a message or enquiry

Make an enquiry

The D type fibre optic sensors are a family of very high performance non contact displacement sensors. With resolutions down to 0.004µm and measuring ranges from 20µm to 50mm, these units also have 100Hz, 20kHz and 200kHz + frequency capability. Their rugged construction and compact size means they are suitable for measurements inside of mechanisms, submerged in fluids and hostile environments. The sensors can measure any surface that reflects light.  They are commonly used in applications where the target moves in the sensor axis such as vibration monitoring.

Model No Linear Range Near side Resolution at 100Hz
Near side
Linear Range Far side Resolution at 100Hz
Far side
Tip Diameter Total Range
D6 50µm 80nm 0.33mm 0.25µm 0.56mm 0.8mm
D12 50µm 8nm 0.4mm 0.1µm 0.56mm 1.75mm
D20 20µm 2nm 0.25mm 0.04µm 0.81mm 1.15mm
D21 250µm 15nm 0.7mm 0.1µm 0.813mm 1.75mm
D47 46µm 10nm 1.3mm 0.1µm 1.61mm 4.7mm
D63 20µm 2nm 0.7mm 0.13µm 3.18mm 2.85mm
D64 38nm 8nm 1.3mm 0.13µm 3.18mm 5.8mm
D100 38µm 8nm 2.3mm 0.2µm 3.18mm 9.6mm
D125 48µm 2nm 3.3mm 0.13µm 3.96mm 15mm
D169 46µm 8nm 4.0mm 0.5µm 4.76mm 19.5mm
D170 64µm 30nm 6.0mm 2.5µm 4.76mm 29.1mm
D171 1.3mm 0.7µm 6.13mm 2.5µm 4.76mm 40.5mm
D240 10mm 1µm 4.5mm 0.5µm 7.92mm 62mm
  • Compact measuring tip down to 0.81mm diameter means sensors can be placed inside mechanisms
  • Fibre optic principle means complete insensitivity to magnetic fields and high voltage electrical fields
  • Can be used where inductance or capacitance sensors do not work
  • Rugged construction; for use in all types of difficult environments such as vacuum, high pressure, cryogenic temperatures, high temperatures, in fluids or explosive atmospheres
  • High frequency capability 200kHz +
  • High resolution down to 0.004µm
  • 0-5 VDC analogue output
  • Actuator stroke
  • Bearing vibration
  • Diaphragm deflection
  • Displacement in fluids
  • Read/write head tracking
  • Piston stroke
  • Solenoid travel
  • Ultra sonic vibration
  • Valve dynamics
  • Piezoelectric crystal vibration
A Provides temperature stabilised electronics for low drift & high accuracy
B Connects sensor system with inline connector (D6, RC12 n/a). *Oprion B is also required for use with vacuum passthru flanges & assemblies Bv2, Bv3, Bv4, BvF
2B Connects sensor system with two inline connectors.  Not available for all models..
B1 Connects sensor system with bulkhead connector (D6, RC12 n/a)
Bv1 Connects sensor system with single channel vacuum passthru for 10 E-7 torr.  Includes ultra-torr compression fitting (D6, RC12 n/a)
Bv133 Same as Bv1 with 1.33” diameter mini-CF type flange for bulkhead mounting
Bv2 2 port single channel vacuum passthru flange for D models for 10 E-11 torr (D6 n/a) *also requires option B
BvF Multi-channel high vacuum passthru assembly for 10 E-7 torr. provides fused fiberoptic passthru and multi-channel vacuum flange assembly. Can accommodate 8 D Ype or 5 RC type sensors. (D6, RC12 & RC20 n/a) *also requires option B
-- Standard Jacket: PVC Monocoil -PVC over a steel helical winding. semi-crush-proof, liquid-tight, not autoclavable or MRI compatible. Good to 105C.
C1 Jacket: stainless steel interlock, crush proof, not liquid tight. good to 850c.
C2 Jacket: silicone - mri and bio-compatible, autoclavable, flexible, liquid-tight, not crush-proof. good to 200C
C3 Jacket: silicone over ptfe wrap - semi-crush-proof. good to 200c. short lengths only
C4 Jacket: corrugated - all plastic. semi-crush-proof, liquid-tight, light-weight, mri compatible. Good to 85C.
C5 Jacket: ptfe over stainless steel interlok - vapor barrier, liquid-tight, crush-proof. good to 260c.
C51 Jacket: ss interlok over ptfe - vapor barrier, liquid-tight, crush-proof, poor flexibility, good to 260c.
C6 Jacket: PVC over nylon wrap - semi-crush-proof, liquid-tight, EMF compatible. good to 105c.
C7 Jacket: ptfe tubing - autoclavable, MRI & EMF compatible, vapor Barrier, liquid-tight. good to 260c.
C8 Jacket: pvc - polyvinyl chloride – very flexible, liquid-tight, EMF & MRI compatible, not autoclavable, not crush-proof. good to 105c.
C9 Jacket: annealed (semi-rigid) stainless steel tubing. liquid tight. good to 850c.
C10 Jacket: silicone over ss interlok sheathing. liquid-tight, crush-proof. good to 200c.
C11 Jacket: polyolefin shrink tubing - thin wall moisture/vapor barrier, not crush-proof, poor flexibility. good to 150C.
C12 Jacket: polyolefin over ss interlok - thin wall moisture/vapor barrier, crush-proof, flexible. good to 150c.
E1 Extra length of fiberoptic cable (some models limited to 10 feet or to 49 feet); any fiber bundle < Ø 2.5mm
E2 Extra length of fiberoptic cable (some models limited to 10 feet or to 49 feet); any fiber bundle > Ø 2.5mm
Fv1 Low vacuum passthru for 10 E-4 torr - provides solid section on fiberoptic cable, compression fitting, and stainless steel interlok sheathing on vacuum side
Fv2 Low vacuum passthru, same as fv1, provides Ø 0.250” x 3”l solid section on fo cable
Fv3 Low vacuum passthru, same as fv1, provides Ø 0.500” x 3”l solid section on fo cable
G1 Additional output, DC coupled with 10x gain and adjustable DC offset
G2 Additional output, AC coupled with 10x gain
H1 High frequency amplifier for d models up to 200KhZ bandwidth
H2 High frequency amplifier for d models above 200KhZ to 1 mhZ bandwidth
+H1 Additional output for D models with bandwidths up to 200KHZ
+H2 Additional output for D models with bandwidths up to 1MHZ
L Low frequency amplifier ( < 20Khz), 100hz std
+L Additional output with low frequency bandwidth ( < 20Khz), 100hz std
M Digital display - DC volts
O Adjustable DC offset
P Polynomial curve fit to specified calculation range
Q Connects AC/DC power adaptor and BNC output
R1 Ambient light rejection
R2 Blue light sensor, 470nm
T1 Tip: straight, customised
T2 Tip: threaded
T3 Tip: non-metalic, (torlon or peek)
T4 Tip: 90° tubing
T5 Tip: 90° square body, unthreaded end
T6 Tip: 90° square body, threaded end
T7 Tip: made to customer specifications
T8 Tip: high temperature, 350°c max.
T9 Tip: high temperature, 480°c max.
T10 Tip: high temperature, >480°c (quartz fibers)
T11 Tip: non-magnetic (brass or aluminium)
T12 Tip: invar (low expansion coefficient)
V Provides sensor amplifier with 0 - 10 volt output
W Window: recessed sapphire epoxied into tip for high pressure or vacuum
Wb Window: sapphire brazed to sensor tip for high pressure or vacuum
For further information or enquiries Give us a call or fill in our online enquiry form
+44 (0)1823 333343