MR343 Encoder

MR343 Encoder

ZapFREE® MRI Safe Linear Incremental Sensor

The MR343 series Fiber Optic Linear Incremental Position Sensor is an innovative all-optical, passive design which is immune to any electro-magnetic interferences such as magnetic fields, lightning and high voltages. The sensor’s non-metallic construction makes the sensor entirely MRI safe, being both immune and invisible to magnetic fields.

In operation, the MR343 Linear Position Sensor is optically connected to an MR340 Controller via a duplex multimode fiber optic link. An incremental film strip passes through the optical pick-up and the phase offset of two light beams create the classical A/B quadrature signals accessible via the controller interface.

As an incremental system, the absolute position must be set every time the system is powered up. To automate this process, Micronor has developed a special “homing” zone left or right of the film’s active area. In operation, the mechanical system starts up in the “homing” zone and moves towards the first line in the active area. This corresponds to the reference or index position on a conventional encoder. As the sensor moves into the active area, the counter can correctly track the absolute position.

The system has built-in diagnostics and can signal any anomaly occurring during sensor operation.


Measurement Parameters
Resolution 100 μm
Maximum Speed 40m/s (based on 100kHz controller bandwidth)
Optical Interface
Connector LC Duplex
Fiber Type Duplex 62.5/125μm, Graded Index Fiber, 0.27NA, Type OM-1
Maximum Distance Up to 1600 meters with MR340 series Controller
MR Attributes ACR Guidance Document for Safe MR Practices 2007
MRI Usage Zones MR343 Sensor is designed for safe use in all MR Zones I-IV
Materials Used

Acetal, ceramic, glass (No ferromagnetic metal or conductive materials are used)

NOTE: The LC Duplex optical connector has some small metal parts. The pigtail length shall assure that the connector end is safely secured outside the MRI bore

Explosive Atmospheres
EX Classification Inherently safe, simple mechanical device when used with MR340 Controller
IEC Ex EPL Mb/Gb/Gc/Db/Dc
Environmental Attributes

Operating: -10°C to +60°C (14°F to +140°F), 0-95% RH, Non-Condensing

Storage: -25°C to +70°C (-13°F to +158°F), 0-95% RH, Non-Condensing

Ingress Protection IP30, Keep free from contaminants
Physical Attributes
Dimensions 30 x 28 x 15 mm (1.18 x 1.10 x 0.59 inches)
Weight (without cable) 10 g (0.3 oz), Cable weight ~10g/m

Specifications subject to change without notice


  • Medical
  • MRI
  • Robotics
  • Industrial


  • 100% passive optical sensor
  • 0.1 mm positional resolution
  • MRI safe design
  • Immune to EMI, RFI, lightning and ground loops
  • Immune and invisible to magnetic fields
  • Inherently Safe, Simple Mechanical Device
  • Fiber optic link can extend up to 1600 meters
  • DIN Rail Mount and OEM PCB Controllers available


CAD Files
Declaration of Conformity

MR343 / MR303 Linear Encoder Demonstration Video

Ordering Information

MR343-B400YYY Where YYY=Optical Interface
YYY Duplex LC Pigtail Length Options: C1R5=1.5m, C03=3m, C05=5m, C10=10m
MR340-1 DIN Rail Mount Controller

Quick Ship Configurations

MR340-0 OEM PCB controller
MR340-1 DIN rail mount controller
MR343-B400C1R5 Linear Sensor, Pigtail Length=1.5m