The basic fiber optic test and measurement tasks include optical power measurement, insertion loss measurement (attenuation), wavelength measurement, and even signal quality measurement. Some equipment directly shows the result while on others you would have to conclude your judgment based on the raw data they display.

:: Fiber Optic Power Meters

Fiber optic power meters measure optical power, which you can conclude from their name. They are composed of a fiber optic adapter, a silicon or germanium detector, signal amplifier circuit and a digital display.

Power meters come in two factors: desktop and handheld portable. In field service and installation, you will use a handheld type for sure. They can display measured optical power in two units: decibel or watts. They have to be calibrated for a precise measurement.

The most popular power meters are calibrated for 850nm, 1310nm and 1550nm, the three major wavelength bands for fiber optic communications.

You have to set up your wavelength before doing the actual test. This is very important since otherwise you would get a totally screwed up result for a different wavelength.

:: Fiber Optic Light Source for Power Measurement

Power meters are no use without a light source. A large variety of light sources are available for different applications and you must have the correct source for your measurement. Light source can range from several hundred dollars to tens of thousands of dollars depending on your testing requirement.

Light source can be divided into several major groups. Here are the major types on the market.

1. Broadband light sources

Broadband light source emits a broad range of wavelengths. The typical sources include tungsten lamps, LEDs and ASE (Amplified Spontaneous Emission) sources. They typical cover hundreds of nanometers.

Broadband light sources are major used in lab and manufacturing floors for spectrum performance analysis and not often used in field services.

2. LED sources

LEDs are widely used in field services as light source for multimode power measurement such as 850nm and 1300nm. LEDs typical emit a range of wavelength covering 50nm up to 100nm.

3. Fixed wavelength laser diode sources

Fixed wavelength laser diodes are widely used in field services. The typical applications include 1310nm single mode and 1550nm single mode systems.

:: Fiber Optic Talk Sets

Fiber optic talk sets are especially designed for installers working on a long fiber link at two points. Installers can use it to communicate and coordinate their work.

Basically what fiber optic talk set does is to turn any of the fiber links into a communication channel or telephone link. It includes both a transmitter and a receiver to send and receive voice signal through the fiber. Most fiber optic talk sets have headsets.

:: Laser Visual Fault Locators

Basically laser visual fault locators are a low cost red color laser source emitting red laser light ranging from 630nm to 670nm. When you inject that red laser light into the fiber, you can see light leaking on breakage points, defective splices, macrobending and other installation errors.

Laser visual fault locators emit much higher power than fiber continuity testers which use a LED red light source. So be careful to distinguish between these two equipment.