OP940 Optical Return Loss Meter and Insertion Loss Meter

OP940 Optical Return Loss Meter and Insertion Loss Meter

The Industry’s fastest & most accurate Optical Return Loss Meter

OP940 Fiber optic Insertion Loss Return loss meter image


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Making your fiber cable assemblies and products with the HIGHEST quality is faster, easier and more efficient with our OP940 Single Channel Optical Return Loss and Insertion Loss Tester.  This loss meter is a very valuable component for R&D, labs or production manufacturing lines where your customers/end users demand the very highest performance from your products.

The OP940 is used around the globe in R&D, Labs, and cable production manufacturing.  This single channel optical return loss meter comes in both desktop and 19″ rack mount sizes.

To test multi-channel fiber optic cable assemblies, pair it with our OP720 Optical Switch for 4-148 channel fiber cables.

Looking to test your fiber cables and products in both directions, add our OP725 Bi-Directional Switch for superfast 6 second tests of a simplex cable for two wavelengths in both directions (See it in action – video).

>> View OP940 Multichannel Version
>> View OP940 Bidirectional Version


Robust and Intuitive Front Panel

The user experience through the front panel of the OP940 is simple and easy to navigate without sacrificing functionality. Test IL and RL simultaneously with results updating in real time. Adjust the RL reference position and measure both front and back connectors. Set pass/fail criteria and engage the colored display to quickly verify a batch of cables. If you’re ever unsure of what to do, help menus are accessible on every screen to guide you through the different features and options.

Identify and Fix Issues with Minimal Downtime

Minimize your production downtime by identifying and troubleshooting issues right through the front panel. Use the optical reflectance trace to find reflections along the optical path caused by dirt or misaligned connectors. If there is a reflection at the front panel, you can remove it to access the connector and perform maintenance without exposing the rest of the unit to the elements.

Wide Dynamic Range for RL Measurements

By making use of a wide dynamic range (SM, FTTX: -10dB to -80dB | MM: -10dB to -58dB) for RL measurements, the OP940 can adjust for attenuation in the reference setup, which results in the most accurate RL results in the industry.

Fastest IL/RL Measurement

Utilizing the OP940, you can test a single channel, dual wavelength, IL and RL in less than 4 seconds.


The OP940 is available with SM, MM, and FTTX wavelengths and a variety of core sizes and detector options to meet your needs.


We proudly design & manufacture our equipment in California, United States.



  • Test Insertion Loss and Return Loss in Seconds
  • Set Return Loss Reference Position and Value
  • Measure Return Loss at Multiple Connection Points through the Front Panel
  • Produce Cable Test Reports or Labels through Software
  • Programmable Pass/Fail
  • Available in Single Mode, Multimode, FTTX
  • On Screen Help
  • Easy to Use
Software B icon

Automate, customize, and record your tests through software.

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Can be calibrated on-site, in-house or remotely.

3 yr Warranty Icon

OptoTest offers a three-year full warranty!

Technical Support

Our team of experts is ready to assist you.


Our 30-Day Guarantee allows a full refund for any reason.
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Talk to one of our sales engineers at +1(805) 987-1700 to learn more about our custom solutions.


Return Loss Single Mode FTTX Multimode
Source Wavelength 1310nm, 1550nm 1310nm, 1550nm, 1490nm, 1625nm 850nm, 1300nm
Measurement Range
-10dB to -80dB -10dB to -80dB -10dB to -58dB
Measurement Linearity ±1dB (-12dB to -72dB) ±1dB (-12dB to -72dB) ±1dB (-10dB to -45dB)
Distance Range up to 2500 meters
Mandrel-free minimum distance 1.7 meters (both reflections <-45dB)
Insertion Loss Single Mode FTTX Multimode
Source Center Wavelength ±30nm from nominal ±30nm from nominal ±30nm from nominal
Source Bandwidth <10nm <10nm <140nm (850nm) <200nm (1300nm)
Internal Fiber 9/125μm (SMF28) 9/125μm (SMF28) 50/125μm, 62.5/125μm, 105/125μm
Launch Condition N/A N/A Available upon request
Output Power* (typical) -1.5dBm -2.5dBm -18dBm(850nm) -20dBm(1300nm):
Insertion Loss Stability** ±0.02dB ±0.02dB ±0.02dB

Measurement Linearity (Relative Accuracy)***
Deviation ± 0.05dB 0dBm to -65dBm at 1490nm
Deviation ± 0.01dB <10dB power variation

*For single channel systems. **Over 1 hour with a max. change of 1ºC. ***For 1, 2, and 3mm detectors.

Measurement Timing Single Mode FTTX Multimode
IL and RL, Dual Wavelength 3s* 6s 3s*
Switching Time (Multichannel) 100ms

* Using the front panel in Dual ILRL mode or running OPL-Pro with real-time update enabled.

Mainframe OP940
Dimensions 8.5” x 3.5” x 12″
Power Supply 90VAC … 264VAC; 47Hz to 63Hz; 0.7Amps (115VAC) 0.4Amps (230VAC); Fuse: T1A, 250V
Warm-up time 5-15 minutes
Operating Temperature 5℃ to 40℃
Maximum Relative humidity* 95%

* For temperatures up to 31°C, decreasing linearly to 50% relative humidity at 40°C.


Advancing the World of Fiber Optics™