OptoTest OP940-SW - User Manual

Questions and Answers

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Alexandra PetersonAug 5, 2025
Why are my OptoTest Measuring Instruments giving unstable measurements?
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  Teresa CarrAug 5, 2025
  Unstable measurements in OptoTest Measuring Instruments can stem from several factors: * **Dirt and damage on endfaces:** Inspect and clean all endfaces, including SAVer cables and the front panel connector. Repolish if necessary. * **Dirt and damage on detectors:** Check detectors and adapters for dirt or damage. Clean as needed and replace damaged adapters. If a detector is damaged, contact OptoTest for repair or replacement. * **Dwell times:** Increase the IL and RL Dwell times in the software or Settings screen to allow detectors more time to stabilize. * **Damaged bulkheads and detector adapters:** If the front panel bulkhead is damaged, contact OptoTest for a replacement or guidance. * **Hybrid bulkheads:** not mentioned.
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Mitchell FergusonAug 12, 2025
What to do if my OptoTest Measuring Instruments unit shows low output power?
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  James ChenAug 12, 2025
  Low output power in OptoTest Measuring Instruments can be caused by: * **Dirt and damage:** Inspect and clean all endfaces, including SAVer cables and the front panel connector on the instrument. Repolish any dirty or damaged connectors. * **Misaligned adapters:** Disconnect and reconnect the FC connector, ensuring proper key alignment. Be aware that hybrid bulkheads, especially SC-LC, can have alignment issues. * **Mismatched fiber size:** Using a 50/125µm fiber instead of 62.5/125µm can cause a 3-5dB power drop. Launching multimode light into a single mode cable can result in a 20dB power drop.
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johnathangonzalezAug 19, 2025
Why does Return Loss on OptoTest Measuring Instruments connectors take time to stabilize?
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  Katherine TaylorAug 20, 2025
  The stabilization time for Return Loss (RL) on connectors in OptoTest Measuring Instruments can be attributed to: * **Connector settling time:** Certain push-in connectors, like SC and E-2000, may require time for the ferrules to align properly due to spring force relaxation. This is more common with new connectors and decreases with use. * **Dirt and damage:** Inspect and clean all endfaces, including SAVer cables and the front panel connector on the instrument. Repolish any dirty or damaged connectors. * **Dwell times:** Increasing the IL and RL Dwell times in software or on the Settings screen of the unit can improve stability by allowing the detectors more time to settle.
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Ralph ParkerAug 27, 2025
What to do if OptoTest Measuring Instruments Return Loss measures 80.1dB (SM) or 58.1dB (MM)?
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  margaret09Aug 27, 2025
  If your OptoTest Measuring Instruments Return Loss measures 80.1dB (SM) or 58.1dB (MM), consider the following: * **Large reflections:** Clean the interfaces. If the issue persists, increase the length of the reference cable by 3-5 meters. A damaged front panel connector may need repolishing or replacement. * **Dirt and damage:** Inspect all endfaces, including any SAVer cables and the front panel connector on the instrument. Clean or repolish any dirty or damaged connectors. * **Connector limitations:** In Scan mode, a high-quality polish on the DUT that exceeds the linearized range of the return loss meter may cause this issue.

Summary

Understanding Instrument Specifications

Navigating the User Interface

Mode Select Screen Navigation

OPM Mode Operations

OPM Mode Functionality

Controls the optical power meter; supports multiple calibrations, absolute/relative modes.

IL Mode for Insertion Loss

IL Mode Functionality

Measures insertion loss for one or two wavelengths, allows referencing.

RL Mode for Return Loss

RL Mode Functionality

Measures return loss for two wavelengths, allows referencing second connector.

ILRL Mode for Combined Measurements

ILRL Mode Functionality

Measures IL and RL simultaneously for one wavelength with live results.

Dual ILRL Mode for Two Wavelengths

Dual ILRL Mode Functionality

Measures IL and RL simultaneously for two wavelengths with live results.

Scan Mode for Diagnostics

Scan Mode Purpose

IL Reference Procedure

IL Ref Screen Functionality

Dedicated screen for referencing insertion loss, applied globally.

RL Reference Procedure

RL Ref Screen Functionality

References return loss and applies temporary adjustments.

RL Reference Process and Options

Configuring Unit Settings

Settings Mode Navigation and Controls

Allows configuration of pass/fail, startup mode, and other parameters.

Checking Unit Status and Settings

Status Mode Information Display

Operating Multichannel Units

Multichannel Mode Screen Adaptations

Bidirectional Operation with OP725

Enabling Bidirectional Mode

Toggle mode via Settings 'External 2x2 Switch' and restart unit.

Bidirectional Mode Operation

Adds A→B/B-A function to switch directions and store references.

Operational Examples and Procedures

Example 1: Referencing and Measuring Return Loss

Step-by-step guide to referencing and measuring return loss.

Example 2: Referencing RL with APC Cables

Instructions for referencing return loss using APC-terminated cables.

Example 3: Referencing and Measuring Insertion Loss

Step-by-step guide to referencing and measuring insertion loss.

Example 4: Bidirectional IL and RL with OP725

Procedure for referencing bidirectional IL and RL using an OP725.

Example 5: OTDR-style Trace in Scan Mode

Using Scan Mode to diagnose problems with OTDR-style traces.

Troubleshooting Common Issues

Troubleshooting Unstable Measurements

Addresses dirt, damage, dwell times, and bulkhead issues causing unstable readings.

Troubleshooting Return Loss Connector Stabilization

Addresses settling time for push-in connectors and hybrid bulkheads.

Troubleshooting Low Output Power

Addresses dirt, misaligned adapters, and mismatched fiber sizes.

Troubleshooting Return Loss Referencing

Addresses issues when the unit will not reference return loss, like APC connectors.

Troubleshooting High Return Loss Readings

Addresses large reflections, dirt, and connector limitations affecting readings.

Removing the Source Panel for Repolishing

Accessing the Front Panel Connector

Repolishing and Reassembly

OptoTest OP940-SW Specifications

General

Wavelength Accuracy	±1 nm
Resolution	0.001 dB
Connector Type	FC/APC
Display	LCD
Power Supply	100-240 VAC, 50/60 Hz
Output Connector	FC/APC
Source Type	Tunable Laser Source
Power Range	+10 to -80 dBm