Better Knewing Optical Power Measurement

As fiber optic system becomes more and more common and has increasingly sophisticated, optical power measuring, the most basic actions for the fiber optic testing process, will also grow more and more complex. To make reliable measurements, people must consider the characteristics and interactions of optical power meter, fiber optic light source, detector types, attenuation, back
reflection, interference, and beam divergence.

Optical Power Meter Measurement

An optical power meter is used to measure the absolute optical power or the relative length of optical fiber optical power loss. Through the measurement of the absolute power of the transmitting end optical network, a power meter to be able to evaluate the performance of the light end equipment. The basic assumption for optical power measurement is the at the meter output reading is
directly proportional to the optical input power. This proportionality property is defined as linearity, and the departure from this direct proportionality is defined as nonlinearity.

Optical Light Source
Optical measurements can be made with a wide variety of light sources. Fiber optic light sources are designed to cover a variety of wavelength ranges to suit all optical testing needs, Light sources are offered in a variety of types including LED, halogen and laser. With the combination of a power meter and stabilized light source, it is possible to measure the connection loss, test continuity and help evaluate the transmission quality of fiber link. Optical Multimeter jor fiber optic multi meter integrates both an optical power meter module and an optical light source module and can perform closed-loop tests by using both modules, and can also work individually.

Optical metering system
Typical optical power measurement system consists of a detector and a display unit that calculates the optical power or energy represented by the electrical signal. The measurements are displayed or stored in convenient formats, such as analog or digital output, or entries in a data-collection file.
The optical detector, which converts an optical signal into an electrical signal, The most common types of optical-signal detectors are photodiodes, thermopiles, and pyroelectric detectors.
Photodiodes use the photon’s energy to create an electron-hole pair, Thermopile detectors are used for high-power laser sources, up to tens of kilowatts of optical power. Pyroelectric sensors are popular for pulsed laser sources. Among these detector types, photodiode sensors are the most widely used.

Light source back inflection
Accurately measuring a modulated or a pulsed light is very difficult as well as the CW (Light source back inflection) light source. When making peak-to-peak measurements, since waveforms can be greatly distorted. Rather tan reading directly from the detector. It is better to record the raw data, and than process it with digital filtering or statistical averaging with the fact of the limitations of the detector’s response time, and the speed of the meter’s circuitry.

To sum up, optical power measurement involved in the application of optical power meter, a stable fiber optic light source as well as the good understanding of the optical setup, the choice of detector types, detector saturation and noise, attenuation.