Raytek Marathon MM Series – Infrared Temperature Sensor


  • Broad temperature range from -40 to 3000°C (-40 to 5432°F)
  • Superior optical resolution to 300:1
  • Spot sizes down to 0.6 mm
  • Fast response times down to 1 ms
  • Easy adjustment with variable focus optics
  • Through-the-lens sighting, optional with laser aiming or video function
  • Video monitoring and image capture capability
  • Compact, rugged housings with IP65 (NEMA-4) rating
  • Smart, two-way digital communications (RS232/485)
  • Programmable relay output
  • Simultaneous analogue and digital outputs
  • Dirty lens alarm

Raytek Marathon MM Series of Infrared Temperature Sensors covers an extensive temperature range from -40 to 3000°C (-40 to 5432°F), featuring six models. Each model operates at specific wavelengths and temperature ranges suitable for low (-40 to 800°C / -40 to 1472°F), medium (250 to 1100°C / 482 to 2012°F), or high temperatures (300 to 3000°C / 572 to 3273°F) in industrial production monitoring.

The latest enhancement to the Raytek Marathon MM Series is the Precision Variable Focus capability. This feature enables quick, easy, and accurate adjustment of the sensor’s focus on measurement targets. Adjustment can be performed either manually with a push-button on the instrument or remotely via an RS232/RS485 PC connection. Real-time video feedback allows for precise adjustments tailored to specific application requirements, minimizing installation time and potential errors.

All sensors feature identical installation hardware and include Raytek DataTemp Multidrop software to enable easy and consistent installation, configuration and data capture across the full breadth of an application:

  • steel and metals processing (foundry/forging operations & heat treating)
  • glass bending, forming, tempering, annealing, and sealing
  • paper processing (ink drying/curing & lamination)
  • plastics processing and thermoforming; and semiconductor processing


Model Temperature Range Spectral Response Response Time (95% response)
LT -40°C to 800°C 8 – 14 µm 120 ms
(-40°F to 1472°F)
G7 300°C – 900°C 7.9 µm 120 ms
(572°F to 1652°F)
G5L 250°C to 1650°C 5 µm 60 ms
(482°F to 3002°F)
G5H 450°C to 2250°C 5 µm 60 ms
(842°F to 4082°F)
MT 250°C to 1100°C 3.9 µm 120 ms
(482°F to 2012°F)
3M 100°C to 600°C 2.3 µm 20 ms
(212°F to 1112°F)
2ML 300°C to 1100°C 1.6 µm 2 ms
(572°F to 2012°F)
2MH 450°C to 2250°C 1.6 µm 2 ms
(842°F to 4082°F)
1ML 450°C to 1740°C 1 µm 2 ms
(842°F to 2732°F
1MH 650°C to 3000°C 1 µm 2 ms
(1202°F to 5432°F)


Raytek Marathon MM Series Infrared Temperature Sensor-DpstarGroup