Calibration of a computer-controlled precision wavemeter for use with pulsed lasers

The design of a pulsed wavemeter to monitor the high-precision tuning of pu lsed (as well as cw) laser sources is presented. This device is developed f rom a combination of silver-coated Fabry-Perot etalons with various plate s pacings. These etalons provide stepwise refinement of the wavelength to be measured. The wavemeter is controlled by a computer through a CAMAC interfa ce, which measures the absolute wavelength in the visible with an accuracy of 2 parts in 10(8). The time required for data acquisition and computation to measure the refined wavelength with a single 2-MHz CPU is less than 100 ms. We describe the calibration of the instrument over the wavelength rang e 400-850 nm. We obtain the required calibration lines by locking lasers on hyperfine transitions of iodine, uranium, rubidium, and cesium. Methods to reduce the number of calibration lines required for calibration of the sys tem are described. The expected wavelength-dependent phase shift of the sil ver coatings is compared with that measured for the etalon following calibr ation. The differences are larger than expected because of either optical a berations or the use of centroids to measure the fringe position. (C) 1999 Optical Society of America.