Wollaston prism-based digital laser wavelength meter

We present a device designed to measure laser output wavelength and based on Wollaston prisms and Barium borate (BBO) crystal polarizers. The arrangement generates a localized fringe plane perpendicular to the optic axis at which a CCD array is placed; consequently, good spatial coherence of the light is not a critical requirement for effective operation of the device. The interferogram is recorded with a digital camera allowing complete pixel registration, which results in improved accuracy. After calibration of the arrangement, the wavelength can then be measured with a precision of better than 1 part in 10 5 , and has been shown to track changes in the output wavelength of the laser sources used. In addition, the calibrated wavelength meter was found to be able to measure the absolute value of a series of defined laser lines to an accuracy of 0.18% (+/- 0.86nm).