Optical power meters are handheld instruments that typically consist of a sensor, measuring amplifier and display. They are designed to test average optical power in fiber optic systems, but can also be used to measure peak power.
Preparation
Optical power meters are an essential piece of equipment for measuring the optical power in fiber cables. They can be used to measure the absolute or relative power in a system, and can also be used to test optical loss. In both cases, the power meter needs to be calibrated at the wavelength being tested.
Calibration can be performed with either a tunable laser or through the logging function of an optical power meter. However, it is important to note that the responsivity of an optical power meter can vary significantly between different wavelengths, which means calibration is needed for every wavelength setting.
For this reason, it is critical that a tunable laser or optical power meter be used with a stable light source. A stable light source is one that has a predictable optical path, which can be easily aligned with the photodiode of an optical power meter.
Some optical power meters use silicon (Si), Germanium (Ge), or Indium-Gallium-Arsenide (InGaAs) semiconductor detectors. Detector material has an impact on responsivity and is a major factor in determining the performance of an optical power meter. For wavelengths supported by standard single-mode fiber from about 1250 nm to 1650 nm, InGaAs detectors provide the highest performance with high responsivity and relatively low wavelength dependence.
Detectors can be found in both handheld and desktop optical power meter devices. Handheld devices have smaller form factors and shorter test arms, which make them ideal for portable use.
The desktop models have longer test arms that can be adjusted for more accurate measurements. They also have larger screen displays and longer battery life, which makes them more practical for use in large network installations.
In addition, the compact design of many handheld power meters is advantageous when testing small, crowded network hardware environments that can be difficult to access without a power meter. The increased charging intervals offered by next-generation handheld optical power meters also improve battery life and reduce the number of recharges required to complete a test.
Whether you need basic fiber verification capabilities, advanced troubleshooting and inspection, or documented loss and power measurement, Fluke Networks offers the first-line fiber instruments to meet your needs. Choose from a variety of kits with configurations that meet your specific testing requirements.
Setup
A power meter fiber optic is an important tool for testing the end-to-end performance of your fiber network. It is used to measure the signal loss, called insertion loss, in a single-mode or multi-mode fiber cable.
Optical power meters use a semiconductor detector to measure the amount of light passing through a fiber optical cable. The detector is typically based on silicon (Si), Germanium (Ge), or Indium-Gallium-Arsenide (InGaAs).
Most power meters are designed to work at wavelengths of 850nm and 1300nm with modest power levels, ranging from -15dBm to -35dBm for multimode links and 0-40dBm for single mode links. Most handheld type power meters are also able to adapt to a variety of connector styles, including SC, ST, FC, SMA, LC, and MU.
Before you begin using your power meter fiber optic, make sure to prepare everything you need for the test. This includes a manual, practice tests, and documents that show how and where all your cables are installed. Having these things on hand helps you to remember all your test results.
To get the most out of your power meter, it’s also recommended to do some practice tests before starting out on a job site. It is also a good idea to document your testing results in a spreadsheet. This way, you can easily reference them later if needed.
Another thing to note is that when measuring power with an optical pon power meter, it is important to know the difference between absolute and relative measurement. Absolute measurements are done directly from the meter, while relative measurements are made with an optical loss measurement device like an OTDR.
Optical power meters are an essential tool for telecom and CATV network installation and maintenance. They are available in a range of sizes and features to meet any installation or maintenance need. They are lightweight and small in size, can operate with batteries for more than 240 hours of continuous operation, and are easy to use. They also have an automatic self calibration function, backlight on-off optional feature, and a large LCD display window.
Test
Power measurements over fiber networks are critical to performance and reliability. This is why optical power meters are the backbone of fiber test equipment for network deployments and maintenance.
Optical power meters use semiconductor detectors to detect light output at a range of wavelengths and power levels commonly used in optical fibers. They can measure power levels up to a few hundred watts, depending on the model.
They can be a rack-mounted unit, hand-held, or even desktop units that interface with computers. Some are equipped with general-purpose interface bus (GPIB) and RS422 serial communication ports for connecting to computer controllers. Others feature a transistor-transistor logic (TTL) circuit for transmitting data.
The meter also features an input for connecting a test cable, and can display the output in dBm or dB. The meter is usually calibrated to a specified wavelength, which makes it easy to compare its measurement with the correct power level for that specific system.
Once a meter is properly calibrated, it can be used to measure the amount of power loss in an individual fiber. This test is done by putting a wavelength of light from an optical light source at one end of the fiber and then measuring the signal loss at the other end with a power meter.
This test is known as the one jumper method and is the most accurate way to measure end-to-end signal loss on a fiber optic cable. However, it requires that the cable be clean before and during testing.
A dirty cable can cause the meter to show higher loss than it should. This can lead to problems with the results and may result in the need for re-testing.
To ensure accuracy and repeatability, it is important to choose an optical power meter that has been factory-calibrated. This is particularly true if you are using the meter in field settings or with multiple sources. It is also advisable to find a manufacturer that has a reputation for quality, service, and support.
Calibration
Power meters are a critical piece of equipment for the installation, maintenance and operation of fiber optic networks. These devices are the most sensitive to contamination, which makes regular traceable calibration necessary to ensure accurate measurements.
Optical power meters are based on diode sensors made from silicon, germanium or indium gallium arsenide. These sensors are spectrally sensitive, so the wavelength of an optical source must be known in order to make an accurate measurement. In the case of a laser or LED, the spectral width of the source must also be known in order to measure its power accurately.
The NIST (National Institute of Standards and Technology) developed a system to provide absolute power calibrations for power fiber optic multimeter. This calibration was achieved by using collimated beams at the three principle wavelength regions used in fiber telecommunications: 850, 1310 and 1550 nm.
A laboratory-grade electrically calibrated pyroelectric radiometer was developed by the NIST for this purpose. The meter was designed to measure light in the 850, 1300 and 1550 nm wavelengths, and the resulting average ECPR power readings are used to establish an absolute power reading.
This method was very successful and now forms the basis of NIST-calibrated optical power meters. It is not difficult to set up and use, but requires careful control of the test sources to ensure that the ECPR’s power change is consistent with the meter’s output.
Another major source of error in optical power meters is the detector-fiber coupling error. The radiation from the fiber is reflected from the window or detector surface back onto the fiber and then into the detector, causing the power meter to read higher than it should. The degree of this effect depends on the type of connector and the quality of its polished surface.
Several other sources of error exist in optical power meters as well. For example, physical movement of the fiber and connector can induce errors that are a factor of several tenths of dB. These factors can cause readings to vary significantly from the reference value.
