The ultimate goal of spectral information processing is to obtain the peak wavelength. However, the internal return light of the fiber coupler, the uneven distribution of the light intensity of the light source, the different response degree of the CCD to different wavelengths of light, and the system noise will affect the system. All of them affect the location of spectral peak. It is necessary to pre-process and then extract the peak wavelength with appropriate algorithm. Below, Shenzhen Liyi spectral confocal manufacturers will talk to you about how to deal with the data of spectral confocal sensor signals?

The spectral information obtained by the spectrometer includes the background light returned from the interior of the fiber and the signal light returned from the surface of the object to be measured. In order to obtain useful signal light, the background light needs to be first collected and then subtracted from the data obtained by the spectrometer. In addition, the effect of uneven distribution of light intensity in the light source spectrum should also be considered.

As can be seen from the figure, the peak wavelength has been shifted, so the light intensity of the source needs to be normalized. In addition, since the sensor generates random noise at each link, spectrum denoising is required. The common spectral denoising methods include median filtering and wavelet function filtering. By comparing different filtering methods, db6 wavelet is finally selected for 6-decomposition forced denoising, because the repeatability of spectral peak localization is better after filtering.

　　Because the CCD pixels in the spectrometer have a certain size that corresponds to discrete sampling of the original spectrum, peak leakage can occur. If the maximum value in the original spectral data is taken as the peak wavelength, the positioning accuracy will be affected, so it is necessary to choose a suitable algorithm to determine the spectral peak position. Centroid method is a commonly used peak location algorithm, which is suitable for processing point signals about peak position symmetry. The formula for the center of mass is