Anritsu says its new MS9715A WDM tester can be used at virtually any stage from manufacturing through maintenance. It operates from 1527 to 1567 nm and has a long-time measurement function that makes it suitable for maintenance and monitoring. Within this function, a built-in wavelength-standard light source automatically performs wavelength calibration to maintain accurate wavelength measurement. The instrument can measure signal-to-noise ratio, channel spacing, gain slope and spectrum. It has ±20-pm linearity and ±50-pm accuracy with a dymanic range of 53 dB at 0.5 nm and 58 dB at 1 nm. Polarization dependence loss is ±0.25 dB.