Fabry Perot Etalon Based Wavelength Sensor

The differential wavelength measurement of the laser is useful for the feedback control of the wavelength. This sensor has application where very precise wavelength control is required. The absolute wavelength measurement takes more time to respond in the order of few hundreds of the milliseconds, which is not tolerable when very accurate control over the wavelength is required. The sensor discussed here is based on FP Etalon interferometer, which measures the differential wavelength very fast and accurate. The single line CCD camera is used to capture the fringe pattern and DSP hardware is used to process the image frame to calculate the differential wavelength of the input laser beam. The image processing algorithm is developed to abstract data from the fringe pattern.