The Advantest TQ8325 is a benchtop digital optical wavelength meter capable of making high-resolution, high-accuracy measurements of the central emitted wavelength of such devices as laser diodes for communications and LEDs. Measurements, which are made by the Michelson interference method, are made using an He-Ne laser as the wavelength standard to ensure high accuracy. A level meter function is provided as well as a convenience in aligning the optical axis for measurement. In addition, its capability to display frequency deviations enables changes in the wavelength to be measured with high accuracy and high resolution.