Adaptive Light Intensity Aided Wavelength Tunning for Phase Shifting Interferometric Measurement System

In phase shifting interferometric measurement system, using wavelength-tuned phase shifting technology to measure optical surface can improve vibration errors. However, the wavelength-tuned phase shifting interferometry is greatly challenged by nonlinear distortion between wavelength-tunned light intensity and voltage modulation, which has a certain impact on phase calculation accuracy. To address this issue, an adaptive light intensity aided interferometric measurement scheme is proposed in this paper. To improve the adjustment time of voltage response, an improved fuzzy single neuron adaptive PID constant amplitude control algorithm is built. By exploiting the online detection and feedback control of light intensity, the stable output of light intensity is integrated into phase shifting measurement system. Experiment results verify that the improvement of light intensity fluctuation range, root mean square(RMS) and peak-to-valley(PV) for measurement repeatability can be achieved with the proposed scheme.