OPM and OLS: Product-Specific Questions
CSM-CSS
Q: How often should CSS1 light sources and CSM1 power meters be calibrated?
A: AFL recommends all test equipment be calibrated every thirty-six (36) months.
Q: Can I connect an APC connector to a CSM1 power meter?
A: Yes, use AFL standard non-angled connector adapters. AFL angled connector adapters are only for use with inspection products to align the connector end-face surface with the scope viewing plane.
Q: What type of adapter cap do I use to connect an angled connector (APC) to a CSM1 power meter?
A: Use AFL standard (non-angled) connector adapters. AFL angled connector adapters are only for use with inspection products to align the connector end-face surface with the scope optical viewing plane. Examples:
- Use SC adapter cap to measure power from SC and ASC connectors
- Use LC adapter cap to measure power from LS and ALC connectors
Q: If I change the connector adapter or test jumper on the CSS1 light source, do I need to reset my reference?
A: Yes, the connection at the light source is the critical connection which determines the light level launched into the test network. Any movement or realignment of the connectors could change this level, which will shift the reference level.
Q: How do I measure power from MPX or MPO/MTP cables with a CSM1 Power Meter (OPM)?
A: AFL OPMs are designed to measure power from in individual fiber. To connect multiple fiber cables, use a fanout cable. Example: A cable with an MPO connector at one end and 12 SC connectors at the other end. The MPO connector will connect to the network cable and the individual SC connectors will provide a means of connecting the OPM to measure the signal level out of each fiber without interference from adjacent fibers.
Q: Can I use the backplane 1.25 mm and 2.5 mm connector adapters with a CSM1 OPM?
A: No. Backplane 1.25 mm and 2.5 mm connector adapters are machined by removing material from the top of the adapter cap, providing a way to view duplex connectors with an OFS300 or VS300 microscope without contact between the opposite connector and the top of the connector adapter. The Backplane connector is not intended for use with OPM’s as ambient light enters through the top of the cap and hits the detector on the power meter, giving an inaccurate power measurement.
Q: Is it safe to look into the transmit port on a CSS1 light source?
A: NO. The practice of looking into any test port is not considered a safe practice. The output power level of all non-visible AFL light sources is Class 1. However, caution must always be used to avoid accidental viewing of a live fiber. The wavelengths used in the fiber optic industry operate in the infrared region, which are invisible to the human eye. Always use caution when handling light sources.
Q: Can I test single-mode fibers with a CSS1-MM LED source?
A: Yes, however, because the starting power level is only -40 dBm, the maximum test distance will be limited to about 20 km or 12 miles.
Q: Can I plug an APC connector into a CSS1 light source?
A: The mating connector on the inside of our light sources is non-angled UPC. We recommend using a hybrid patch cable (UPC to APC). While an APC connector can be physically connected to the output adapter, the launch power will suffer a loss of approximately 3 dB.
Optical Loss Test Kits
Q: What is the dynamic range of a test kit?
A: The dynamic range of the test kit is the output power of the source minus the minimum level the power meter can measure.
Dynamic range calculations for multimode networks
If an LED source has an output of -20 dBm and the power meter used can measure down to -60 dBm, then the effective dynamic range is: (-20 dBm) – (-60 dBm) = 40 dB.
Q: How does this 40 dB of effective dynamic range translate to measurable fiber length?
A: Calculate the Link Loss Budget based on ISO and TIA standards values and a typical MM network:
- Multimode networks are typically < 3.0 km.
- Optical loss per km on MM fibers at 850nm = 3.5 dB/km
- Connector loss per mated pair is typically ≤ 0.75 dB.
- Assuming two connector pairs (connections) in a network, the Link Loss Budget for this network @ 850nm calculates to: 3.0 km * 3.5 dB/km + (2 connector pairs) * 0.75 dB / (connection) = 12 dB
Thus, to test a typical multimode network, a test kit would need a minimum dynamic range of 12 dB. All of the AFL power meters can measure down to at least -50 dBm; when used with an AFL MM LED source with an output power of -20dBm, the minimum dynamic range is 30 dB for multimode test kits.
Dynamic range calculations for single-mode networks:
- Step 1: Determine the output power level of the laser source and the minimum level the power meter can measure. The dynamic range of the test kit is the output power minus the minimum level the power meter can measure.
- Step 2: Calculate the length of the fiber being tested and the optical loss per km at the test wavelength. (40 dB / 0.25 dB/km @ 1550nm = 160 km or roughly 99 miles).
Note that this calculation does not take into consideration any losses associated with splices or connectors.
Q: Do I need to set my reference with one patch cable or two?
A: There are three reference jumper methods used in industry.
- One Jumper Method is the preferred test method per EIA/TIA 568-C standard. The one jumper method provides test results inclusive of the connections made at the reference jumpers to the cabling link and all cabling splices that may be within the cabling link. See TIA 568-C.0 Appendix E for further details.
- Two Jumper Method requires a reference jumper on both the light source and power meter and a bulkhead adapter. The bulkhead adapter is used to mate the jumpers during the referencing. When the reference is set, the loss induced by the mated pair at the bulkhead is included in the reference. Use of this method may underestimate the loss of the network by as much as 0.75 dB due to the inclusion of the mated pair during referencing.
- Three Jumper Method is the preferred method for ISO and is typically used in cases when the network connector type differs from the user’s power meter.
Q: When testing my single-mode fibers, the loss readings at 1550 nm are higher than the readings at 1310 nm. Why?
A: Fiber is more sensitive to bending losses in the 1550 nm wavelength range than at 1310nm. To try to remedy the difference in loss readings, remove sharp bends or tie-wraps from the fiber and retest the link.
Q: If you are testing a 62.5/125 µm multimode link, can a 50/125 µm reference jumper be used?
A: It is not recommended. To ensure accurate results the fiber type of the reference jumpers must match the fiber type used in the link under test, Technical reason: Transmitting light from a 50/125 µm jumper into a 62.5/125 µm fiber will result in minimal loss. However, transmitting from a 62.5/125 µm jumper into a 50/125 µm network will result in an approximate 2.5 – 3.0 dB loss.
Q: If I am setting a reference with a multimode test kit from Noyes, what should my reference level be?
A: AFL multimode source typical output is -20 dBm.
- For a 50/125 m jumper reference level should be-23 dBm +/- 1 dB.
- For a 62.5/125m jumper, the reference level should be -20.0 +/- 1 dB.
Q: Can I test single-mode fibers with my MLP test kit?
A: Yes, however, because the starting power level is only -40 dBm, the maximum test distance will be limited to about 20 km or 12 miles.OPM and OLS: Product-Specific Questions
CSM-CSS
Q: How often should CSS1 light sources and CSM1 power meters be calibrated?
A: AFL recommends all test equipment be calibrated every thirty-six (36) months.
Q: Can I connect an APC connector to a CSM1 power meter?
A: Yes, use AFL standard non-angled connector adapters. AFL angled connector adapters are only for use with inspection products to align the connector end-face surface with the scope viewing plane.
Q: What type of adapter cap do I use to connect an angled connector (APC) to a CSM1 power meter?
A: Use AFL standard (non-angled) connector adapters. AFL angled connector adapters are only for use with inspection products to align the connector end-face surface with the scope optical viewing plane. Examples:
- Use SC adapter cap to measure power from SC and ASC connectors
- Use LC adapter cap to measure power from LS and ALC connectors
Q: If I change the connector adapter or test jumper on the CSS1 light source, do I need to reset my reference?
A: Yes, the connection at the light source is the critical connection which determines the light level launched into the test network. Any movement or realignment of the connectors could change this level, which will shift the reference level.
Q: How do I measure power from MPX or MPO/MTP cables with a CSM1 Power Meter (OPM)?
A: AFL OPMs are designed to measure power from in individual fiber. To connect multiple fiber cables, use a fanout cable. Example: A cable with an MPO connector at one end and 12 SC connectors at the other end. The MPO connector will connect to the network cable and the individual SC connectors will provide a means of connecting the OPM to measure the signal level out of each fiber without interference from adjacent fibers.
Q: Can I use the backplane 1.25 mm and 2.5 mm connector adapters with a CSM1 OPM?
A: No. Backplane 1.25 mm and 2.5 mm connector adapters are machined by removing material from the top of the adapter cap, providing a way to view duplex connectors with an OFS300 or VS300 microscope without contact between the opposite connector and the top of the connector adapter. The Backplane connector is not intended for use with OPM’s as ambient light enters through the top of the cap and hits the detector on the power meter, giving an inaccurate power measurement.
Q: Is it safe to look into the transmit port on a CSS1 light source?
A: NO. The practice of looking into any test port is not considered a safe practice. The output power level of all non-visible AFL light sources is Class 1. However, caution must always be used to avoid accidental viewing of a live fiber. The wavelengths used in the fiber optic industry operate in the infrared region, which are invisible to the human eye. Always use caution when handling light sources.
Q: Can I test single-mode fibers with a CSS1-MM LED source?
A: Yes, however, because the starting power level is only -40 dBm, the maximum test distance will be limited to about 20 km or 12 miles.
Q: Can I plug an APC connector into a CSS1 light source?
A: The mating connector on the inside of our light sources is non-angled UPC. We recommend using a hybrid patch cable (UPC to APC). While an APC connector can be physically connected to the output adapter, the launch power will suffer a loss of approximately 3 dB.
Optical Loss Test Kits
Q: What is the dynamic range of a test kit?
A: The dynamic range of the test kit is the output power of the source minus the minimum level the power meter can measure.
Dynamic range calculations for multimode networks
If an LED source has an output of -20 dBm and the power meter used can measure down to -60 dBm, then the effective dynamic range is: (-20 dBm) – (-60 dBm) = 40 dB.
Q: How does this 40 dB of effective dynamic range translate to measurable fiber length?
A: Calculate the Link Loss Budget based on ISO and TIA standards values and a typical MM network:
- Multimode networks are typically < 3.0 km.
- Optical loss per km on MM fibers at 850nm = 3.5 dB/km
- Connector loss per mated pair is typically ≤ 0.75 dB.
- Assuming two connector pairs (connections) in a network, the Link Loss Budget for this network @ 850nm calculates to: 3.0 km * 3.5 dB/km + (2 connector pairs) * 0.75 dB / (connection) = 12 dB
Thus, to test a typical multimode network, a test kit would need a minimum dynamic range of 12 dB. All of the AFL power meters can measure down to at least -50 dBm; when used with an AFL MM LED source with an output power of -20dBm, the minimum dynamic range is 30 dB for multimode test kits.
Dynamic range calculations for single-mode networks:
- Step 1: Determine the output power level of the laser source and the minimum level the power meter can measure. The dynamic range of the test kit is the output power minus the minimum level the power meter can measure.
- Step 2: Calculate the length of the fiber being tested and the optical loss per km at the test wavelength. (40 dB / 0.25 dB/km @ 1550nm = 160 km or roughly 99 miles).
Note that this calculation does not take into consideration any losses associated with splices or connectors.
Q: Do I need to set my reference with one patch cable or two?
A: There are three reference jumper methods used in industry.
- One Jumper Method is the preferred test method per EIA/TIA 568-C standard. The one jumper method provides test results inclusive of the connections made at the reference jumpers to the cabling link and all cabling splices that may be within the cabling link. See TIA 568-C.0 Appendix E for further details.
- Two Jumper Method requires a reference jumper on both the light source and power meter and a bulkhead adapter. The bulkhead adapter is used to mate the jumpers during the referencing. When the reference is set, the loss induced by the mated pair at the bulkhead is included in the reference. Use of this method may underestimate the loss of the network by as much as 0.75 dB due to the inclusion of the mated pair during referencing.
- Three Jumper Method is the preferred method for ISO and is typically used in cases when the network connector type differs from the user’s power meter.
Q: When testing my single-mode fibers, the loss readings at 1550 nm are higher than the readings at 1310 nm. Why?
A: Fiber is more sensitive to bending losses in the 1550 nm wavelength range than at 1310nm. To try to remedy the difference in loss readings, remove sharp bends or tie-wraps from the fiber and retest the link.
Q: If you are testing a 62.5/125 µm multimode link, can a 50/125 µm reference jumper be used?
A: It is not recommended. To ensure accurate results the fiber type of the reference jumpers must match the fiber type used in the link under test, Technical reason: Transmitting light from a 50/125 µm jumper into a 62.5/125 µm fiber will result in minimal loss. However, transmitting from a 62.5/125 µm jumper into a 50/125 µm network will result in an approximate 2.5 – 3.0 dB loss.
Q: If I am setting a reference with a multimode test kit from Noyes, what should my reference level be?
A: AFL multimode source typical output is -20 dBm.
- For a 50/125 m jumper reference level should be-23 dBm +/- 1 dB.
- For a 62.5/125m jumper, the reference level should be -20.0 +/- 1 dB.
Q: Can I test single-mode fibers with my MLP test kit?
A: Yes, however, because the starting power level is only -40 dBm, the maximum test distance will be limited to about 20 km or 12 miles.