| Although having high measurement accuracy, traditional monochromatic laser interferometer is usually vulnerable to vibration cause of the phase-shifting process. Besides, monochromatic laser interferometer has phase ambiguity, which limits its use on measurement of step surfaces. However, spectrally-resolved white light interferometry doesn't have these two problems. It obtains the surface shape by analyzing the spectral information of the white light's interference pattern. Because only one frame of interferogram is needed, it is insensitive to vibration, thus can be applied in industrial manufacturing to do on-line surface measurement.A new method based on spectrally-resolved white light interferometry is proposed to measure two-dimensional surfaces. A F-P etalon is applied to divide the continuous spectrum of white light source into a comb- like spectrum with certain interval. With the comb spectrum as light source, interferograms under adjacent wavelength will be separated apart by certain distance, thus avoiding the spectral information of each location overlap each other. By sacrificing certain measuring area, one can obtain the 2-D surface's shape in only one frame.In this paper, some theoretical analysis about single frame interferomery is firstly presented, simulation analysis is carried out to help select appropriate component for each module. An experimental system is setup to achieve a one-dimensional single-frame measurement, the result is improved by using the monochromatic phase. Then based on this, some change is introduced into this system so it can be used on two-dimensional measurement. A narrow two-dimensional level surface is tested using this improved system.The last part of this paper analyzed the experimental error various devices may bring in. And put forward some method to avoid or decrease the effect on measurement result. With some improvement on the deficiencies, this system would be widelv used on on-line test and may create tremendous value. |
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