Using the wavelet transform for processing signals of a counter of speckle

A. Ventura-Chavez; Rene A. Martinez-Celorio; Juan J. Rosales-Garcia; Luis Marti-Lopez; Oscar G. Ibarra-Manzano

doi:10.1117/12.611630

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14 February 2005 Using the wavelet transform for processing signals of a counter of speckle

A. Ventura-Chavez; Rene A. Martinez-Celorio; Juan J. Rosales-Garcia; Luis Marti-Lopez; Oscar G. Ibarra-Manzano

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Proceedings Volume 5776, Eighth International Symposium on Laser Metrology; (2005) https://doi.org/10.1117/12.611630
Event: Eighth International Conference on Laser Metrology, 2005, Merida, Mexico

Abstract

In this paper we describe a speckle speedometer based on the use of the wavelet transform for signal processing. The optical set-up is composed of the moving object, a He-Ne laser, a converging lens, a pinhole and a linear photodetector. The pinhole permits irradiance measurements within a single speckle. The random signal from the photodetector was digitized by a commercially available data acquisition card and saved in a personal computer, where it is processed with wavelet transform. The wavelet transform allows discomposing the signal in several coefficients that represent low-pass and high-pass filters applied to the signal at different frequencies. From processed data the base frequency of the signal can be obtained. That frequency is related to the speed of the moving object, which can be determined after calibration. To test the method we carried out a digital simulation of the system and experiments. In the experiment we measure the speed of points of a rotating disc of glass and compare it with the values obtained from simulations. A good correspondence between measurements and simulated speed values were obtained. Advantages and disadvantages of the method are discussed.

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A. Ventura-Chavez, Rene A. Martinez-Celorio, Juan J. Rosales-Garcia, Luis Marti-Lopez, and Oscar G. Ibarra-Manzano "Using the wavelet transform for processing signals of a counter of speckle", Proc. SPIE 5776, Eighth International Symposium on Laser Metrology, (14 February 2005); https://doi.org/10.1117/12.611630

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