Real-Time Direction Judgment System for Dual-Frequency Laser Interferometer.

Current real-time direction judgment systems are inaccurate and insensitive, as well as limited by the sampling rate of analog-to-digital converters. To address this problem, we propose a dynamic real-time direction judgment system based on an integral dual-frequency laser interferometer and field-programmable gate array technology. The optoelectronic signals resulting from the introduction of a phase subdivision method based on the amplitude resolution of the laser interferometer when measuring displacement are analyzed. The proposed system integrates the optoelectronic signals to increase the accuracy of its direction judgments and ensures these direction judgments are made in real time by dynamically controlling the integration time. Several experiments were conducted to verify the performance of the proposed system. The results show that, compared with current real-time direction judgment systems, the proposed system makes accurate judgements during low-speed motions and can update directions within 0.125 cycles of the phase difference change at different speeds. Moreover, a sweep frequency experiment confirmed the system's ability to effectively judge dynamic directions. The proposed system is capable of accurate and real-time directional judgment during low-speed movements of a table in motion.

Separation and compensation of nonlinear errors in sub-nanometer grating interferometers.

In this paper, to separate and compensate the nonlinear error in the grating interferometer, we analyze the source and generation mechanism of this error, deduce the nonlinear error model of the measured signal and the calculated phase signal, and study the characteristics of the established nonlinear error model. The reason why the frequency multiples of ideal phase signals and higher-order nonlinear errors caused by ghost reflections and angular errors of the laser's z-axis are not integers is explained. Then, a nonlinear error separation and compensation method based on cross-correlation coefficient is proposed. Experiments show that the frequency multiplier relationship between the high-order nonlinear error and the ideal interference signal is close to but not equal to 3-fold. The peak-to-peak value of the compensated nonlinear error is reduced from 17.40 nm to 7.05 nm.

Design and Implementation of a Subnanometer Heterodyne Interference Signal Processing Algorithm with a Dynamic Filter.

In this study, a subnanometer heterodyne interference signal processing algorithm with a dynamic filter is proposed. The algorithm can effectively reduce the measurement error caused by the noise introduced in the optical path and circuit. Because of the low signal-to-noise ratio of the measurement signal, a dynamic filter with variable coefficients is designed. The role of the bi-quadrature lock-in amplifier algorithm in the problem of different amplitudes among the measurement signal, reference signal, and uncertainty of the frequency difference of the dual-frequency laser is analyzed. With the aid of the heterodyne interferometry platform, the error in the solution results of the proposed algorithm and the conventional algorithm is compared. The results indicate that the maximum deviation of the phase increment of the algorithm does not exceed 6 mrad, the single-cycle phase difference can be subdivided by 1024, and the system resolution reaches 0.15 nm.

Adaptive multidirectional frequency domain filter for noise removal in wrapped phase patterns.

In order to avoid the detrimental effects of excessive noise in the phase fringe patterns of a laser digital interferometer over the accuracy of phase unwrapping and the successful detection of mechanical fatigue defects, an effective method of adaptive multidirectional frequency domain filtering is introduced based on the characteristics of the energy spectrum of localized wrapped phase patterns. Not only can this method automatically set the cutoff frequency, but it can also effectively filter out noise while preserving the image edge information. Compared with the sine and cosine transform filtering and the multidirectional frequency domain filtering, the experimental results demonstrate that the image filtered by our method has the fewest number of residues and is the closest to the noise-free image, compared to the two aforementioned methods, demonstrating the effectiveness of this adaptive multidirectional frequency domain filter.

TRIM59 attenuates ox-LDL-induced endothelial cell inflammation, apoptosis, and monocyte adhesion through AnxA2.

Background: Atherosclerosis (AS), a chronic inflammatory vascular disease, is a cause of heart attack and ischemic stroke. Tripartite motif-containing protein 59 (TRIM59), a member of the tripartite motif family, has been reported to be involved in inflammatory diseases. This study was to investigate the role of TRIM59 in oxidized low-density lipoprotein (ox-LDL)-induced endothelial cells and examine the mechanism of TRIM59. Methods: To simulate a cellular model of AS in vitro, varying concentrations of ox-LDL (i.e., 20, 40, 60, 80, and 100 µg/mL) were used to treat the human umbilical vein endothelial cells (HUVECs) for 24 h. The messenger ribonucleic acid (RNA) and protein levels of TRIM59, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), and annexin 2 (AnxA2) were examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot. The transfection efficacy of overexpression (Ov)-TRIM59 and small-interfering RNA-AnxA2 was examined by RT-qPCR and western blot. Cell counting kit-8 assays, lactate dehydrogenase (LDH) assays, enzyme-linked immunosorbent assays, and terminal-deoxynucleotidyl transferase mediated nick end labeling staining were used to examine viability, LDH expression, inflammation, and apoptosis in HUVECs. The protein levels of B-cell lymphoma 2, Bcl-2-associated X (BAX), cleaved caspase3, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 were assessed by western blot. Additionally, the adhesion of THP-1 to ox-LDL-induced HUVECs was detected using monocyte adhesion assays and the binding of TRIM59 and AnxA2 was verified by co-immunoprecipitation. Results: This study showed that TRIM59 expression was decreased in the ox-LDL-induced HUVECs while LOX-1 expression was increased. After transfection with Ov-TRIM59, TRIM59 in ox-LDL-induced HUVECs was increased, and TRIM59 overexpression alleviated the viability damage, inflammation, and apoptosis of the ox-LDL-induced HUVECs. In addition, THP-1 adhesion to the ox-LDL-induced HUVECs was also suppressed by TRIM59 overexpression. This study also showed that TRIM59 could bind to AnxA2 and promote AnxA2 expression in ox-LDL-stimulated HUVECs. Moreover, the rescue experiments revealed that TRIM59 suppressed the viability damage, inflammation, apoptosis, and monocyte adhesion of the ox-LDL-induced HUVECs via AnxA2. Conclusions: TRIM59 protected against ox-LDL-induced AS by binding to AnxA2.