The back reflection meter is a direct display instrument which can measure back reflection, insertion loss, and power of single mode or multimode fiber-optic devices such as connectors, components, and complete systems. For the calculation of back-reflection, it measures the difference of output power and reflected power and displays it on the screen. The absolute accuracy of back-reflection measurements made with the meter is dependent on the level of back-reflection to be measured. Some of the parameters which affect the measurement range are operating wavelengths, power, and fiber type.