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The WA-2500 Wavemeter Jr is an instrument for wavelength measurement of CW laser sources that combines accuracy with ease of use. The accuracy is 1 part in 10,000 over the full wavelength range.

The primary application for Model WA-2500 is measurement of the wavelength or the frequency of tunable lasers that operate from 400 to 1800 nanometers; including dye lasers, Ti:Sapphire lasers and diode lasers. Two internal detectors are provided to cover this range with high sensitivity. The VIS detector is used for lasers operating from 400 to 1100 nanometers, and the IR detector for lasers that operate from 600 to 1800 nanometers.

Two modes exist for the measurement cycle. In the standard mode, the measurement is performed and displayed every 200 milliseconds. When the AVERAGE button is depressed, the data is accumulated for 10 sequential measurements and the display is updated with the average value every 2 seconds.

The WavemeterJr upper front panel includes a six digit LED display and a bar-graph intensity meter. The intensity meter indicates the peak to peak intensity of the interferometer fringe signal, and can be used to facilitate alignment of the beam receiver with the input laser beam. A "LO SIG" or "HI SIG" message will also be flashed on the display when a low or high input intensity condition exists. Three BNC coaxial connectors on the rear panel allow you to diagnose the operation of the instrument with an oscilloscope. These are labeled MONITOR, WINDOW, and TRIGGER. Together, they enable the user to observe the fringe signals from the Michelson interferometer in order to align the beam receiver, optimize the alignment of the interferometer’s adjustable mirror, and analyze the characteristics of the laser input.

The auto-resolution feature built into the Wavemeterjr circuitry allows the instrument to measure the wavelength of lasers with linewidths as great as 3000 GHz, despite the associated low coherence length. The auto-resolution circuitry automatically adjusts the measurement range to be consistent with the coherence length, and the result is displayed with relevant precision.

You can select any one of four display units for the Wavemeterjr readout. To change the display units selection, press the UNITS button on the lower front panel until the desired selection appears on the upper front panel.
• VACUUM WAVELENGTH in nanometers (nm/vac)
• VACUUM FREQUENCY in wavenumbers (cm -1 /vac)
• AIR WAVELENGTH in nanometers (nm/air)
• AIR FREQUENCY in wavenumbers (cm -1 /air)