VICTOR, N.Y. — The best way to determine the absolute wavelength of CW lasers is with the 621 Series Laser Wavelength Meter. This system provides real-time wavelength information measured to an accuracy as high as ±0.2 parts per million. This accuracy is guaranteed by continuous calibration with a built-in wavelength standard which ensures the reliable accuracy that is needed to generate the most meaningful experimental results. Two versions of the 621 series are available. The model 621A is offered for the most demanding experiments, measuring absolute laser wavelength to the highest accuracy of ±0.2 parts per million (±0.0002 nm at 1000 nm). For experiments that are less exacting, the model 621B is a lower-priced alternative. This system measures wavelength to an accuracy of ±0.75 parts per million (±0.0008 nm at 1000 nm). The model 621 is available in several broad wavelength configurations to satisfy virtually any experimental requirement. These are the VIS (375-1100 nm), NIR (520-1700 nm), IR (1-5 µm), and MIR (2-12 µm). The laser under test enters the VIS and NIR systems through a pre-aligned fiber-optic input to ensure optimum alignment. Since fiber is not readily available for infrared wavelengths, the laser under test enters the IR and MIR systems through a free-space aperture, through which the internal HeNe reference laser is emitted as a visible tracer beam to facilitate alignment. Measurements are made at a rate as high as 10 Hz resulting in virtually instantaneous reporting. For the VIS and NIR versions, optical power is measured simultaneously to provide a more complete analysis of laser performance. The 621 Series Laser Wavelength Meter operates with a PC running under Windows. Wavelength is calculated and then transferred to the PC using a high-speed USB interface. Display software is provided to report data and control measurement parameters.