Comparison and application of wavelet transform and Kalman filtering for denoising in δ13CO2 measurement by tunable diode laser absorption spectroscopy at 2.008 µm: retraction.

The referenced article [Opt. Express25, A896 (2017)] has been retracted.

Comparison and application of wavelet transform and Kalman filtering for denoising in δ13CO2 measurement by tunable diode laser absorption spectroscopy at 2.008 µm.

We propose to use the wavelet transform and Kalman filter methods for processing noise in δ13CO2 measurement using laser absorption spectroscopy at 2.008 µm and they have been shown to be useful tool for reducing the intrinsic noise of the optical system. Through the performance comparison and analysis of these two denoising techniques for the intrinsic noise reduction of optical system, it can be found that the Kalman filter is a more suitable approach for the extraction of gas isotope measurement signal from a contaminated signal.

[Precision measurement of the birefringence of quartz crystal at 1 310 nm based on the spectroscopic ellipsometer].

In order to get the precision measurement of birefringence of quartz crystal at the communication wavelength 1310nm, based on the principle of precision measurement of phase difference between P and S polarized lights of spectroscopic ellipsometer, a method for precision measurement of birefringence of crystal was designed through the analysis of the Jones matrix under the transmission mode, and the precision measurement of birefringence of quartz crystal at 1 310 nm at room temperature (22 degrees C) was made, the measuring results and error analysis show that the precision reached 10(-6) level, this is the most precise birefringence parameter available, and it is of important significance for the improvement of designing precision of phase retardation devices of quartz.

[New method for wave-plate orientation determination based on the shape of the modulated spectrum].

A new method for the determination of fast axis of wave-plate is introduced. Based on the principle of electro-optic phase compensation in the wave-plate phase measuring method, the relation between the polarization extinction system out-put signal and the modulating signal can be acquired through the composition of frequency fixed alternating voltage modulation signal. Through the analysis of this process with Jones matrix, the out-put signal was usually found to be the composition of fundamental frequency and second harmonic frequency, the composition signal reflects the axis information as well as the phase information of the wave-plate, and this phenomenon has never been noticed before. Through the analysis of this phenomenon, the transformation trends of the composed wave-form by rotating of wave-plates with different orientations were deduced, and through the observation of the transformation trend, one can easily distinguish the fast and slow axes of wave-plates with phase retardation > pi as well as those with phase retardation < pi, and their phenomena are reverse to each other.

[X-ray diffraction quantitative analysis with polynomial-fit method for polycrystalline materials].

The polynomial-fit method for XRD quantitative analysis of polycrystalline materials is presented in this paper, which combines a mathematic function model with computer technology. Based on the construction of diffraction peak mathematic function model, the XRD atlases from experiments were analyzed by means of polynomial whole pattern fitting to the spectral lines using computer software, then the integral intensities of every peak and weight percentages of each phase could be obtained accurately. This paper mainly includes three parts: 1. According to the fact that the diffraction atlases of mixture are weighted superposition of the powder diffraction atlases of each component and the weight factor of each component is relevant to its volume fraction or weight percentage, the theory of polynomial whole pattern fitting is constructed and the weight factor and weight percentage can be worked out. 2. Describe the method and procedure of data acquisition and analysis. 3. Discuss the result of quantitative analysis. The polynomial-fit method not only simplifies the process of data handling, but also increases the accuracy of analytical result.