MR348 Encoder

MR348 Encoder

MRI-Compatible Fiber Optic Incremental Encoder

The MR348 series ZapFree® Fiber Optic Incremental Sensor is an entirely passive, non-metallic incremental rotary encoder designed for use in Magnetic Resonance Imaging (MRI), nanomagnetic detection, EMC test labs, and similar applications where immunity and transparency to electromagnetic fields is required. The passive, all-optical sensor connects to the remote controller via a standard duplex 62.5/125 multimode optical fiber link.

The remote MR340 Controller Module transmits and converts optical signals to/from the sensor. The controller’s multiple built-in interfaces insure compatibility with industry standard motor drives, PLCs, quadrature counters and motion control systems.


Measurement Parameters
Resolution 360ppr (Contact Micronor for special requirements)
Max Speed 6000 RPM (Contact Micronor for special requirements)
Mechanical Parameters
Rotor Moment of Inertia 5.455E-7 kg*m2
Starting Torque 1.93E-4 N*m
Max Shaft Loads Radial = 60 N (13.5 lbf), Axial = 30 N (6.75 lbf)
System MTBF

L10 bearing life calculated at 50% of max. radial and axial load at 1000 RPM:

3.01E+06 hours (343.2 years)

Optical Interface
Optical Interface LC Duplex, 62.5/125μm Graded Index Fiber, 0.275NA, Type OM1
Link Length Up to 2000 meters (3280 ft) with MR340 Controller
MR Attributes ACR Guidance Document for Safe MR Practices
MRI Useage Zones MR348 sensor is designed for safe use in all MR Zones I-IV
Materials Non-metallic except for fiber optic connector end, ceramic bearings, polycarbonate shaft
Explosive Atmospheres Inherently Safe, Simple Mechanical Device
EX Classification Inherently safe, simple mechanical device when used with MR320 Controller
IEC Ex EPL Mb/Gb/Gc/Db/Dc
Environmental Attributes
Temperature/Humidity +10°C to +35°C, 0%-95% RH (non-condensing)
Ingress Protection IP50 (Contact Micronor for special requirements)
Physical Attributes
Housing Dimension Ø58 mm x 58 mm
Unit Weight 280 g (9.75 oz)

Specifications subject to change without notice


  • 100% passive sensing design – no electronics whatsoever
  • Non-metallic for safe use in MRI Zone
  • Immune and transparent to electromagetic fields – does not leave artifacts in MRI scans
  • Immune to lightning and high voltages
  • Sensor can be installed in all manner of hazardous and potentially explosive atmospheres – mines, gas and dust
  • Outdistances copper, link lengths to 2000 meters

Ordering Information

MR348-D06YYY Where YYY=Optical Interface
YYY Options: C05=5m Pigtail , C10=10m Pigtail
MR340-1 DIN Rail Mount Controller


Quick Ship Configurations

MR340-0 OEM PCB controller
MR340-1 DIN Rail Mount Controller
MR348-D06C05 MRI Safe Size 58mm Encoder, 360ppr, Duplex LC Pigtail Length=5