Lujun Cui

Alignment Method for Linear-Scale Projection Lithography Based on CCD Image Analysis

This paper presents a method to improve the alignment accuracy of a mask in linear scale projection lithography, in which the adjacent pixel gray square variance method is applied to a charge-coupled device (CCD) image to obtain the best position of the focal length of the motherboard and then realize the alignment of the focal plane. Two image positions in the focal plane of the CCD are compared with the traits overlap according to the image splicing principle, and four typical errors are corrected on the basis of the total grating errors. Simultaneously, the rotation error of the mask is used to summarize the grayscale variation function of the CCD image. Threshold functions are employed to express the factors including the wave crests of the amplitude, period error, and phase error, which govern the rotation accuracy and weight alignment accuracy expression of the established four error factors. Finally, in the experiment, the slope of the mask is corrected and adjusted to the same direction as the slide plate with the assistance of a dual-frequency laser interferometer. The effect of the alignment error on the lithography accuracy is discussed and verified in the static case, and it is found that the CCD maximum resolution pixel is 0.1 μm and accuracy of the scale is 0.79 μm in only a 200-mm-measurement range.

Artificial neural network compensation for an optical fiber temperature sensing system based on optical time offset

Through analyzing the optical time offset in optical fiber, the paper presented a new method that using optical fiber sensing technology for monitoring the temperature. Measurement experiments of monitoring temperature were carried out. Through the analysis of experimental data, the results indicated that the temperature variations could be detected by the optical fiber sensor based on optical time offset effectively, and the temperature sensitivity of the optical fiber sensing system is about 2.46mV/°C. Owing to the temperature sensor was affected by the variations and noises seriously, the artificial neural network (ANN) was introduced to the temperature sensor based on optical time offset as a compensation method, experimental results and numerical simulation indicated that the optical fiber temperature sensor with artificial neural network could enhance the nonlinear correction for sensor and decrease the interference effectively. Simultaneously, by way of the contrast test of the different neural networks, experimental results showed that the linearity of full scope could reach 0.11% for temperature sensor based on BRF network, and concluded the BRF network was more suitable for compensation of optical temperature sensor based on optical time offset.

Experimental research on a reflective optical fiber bundle hydrogen gas sensor

Purpose Long life and high hydrogen sensitivity are the crucial performance parameters for an optical fiber hydrogen sensing membrane, and these are the fundamental areas of study for an optical fiber hydrogen sensor. Considering that a traditional optical fiber hydrogen sensor based on pure palladium cannot meet the expectations for long life and rapid sensitivity simultaneously, the experiment in this paper designed a kind of reflective optical fiber bundle hydrogen gas sensor based on a Pd0.75–Ag0.25 alloy to achieve a hydrogen sensing system. This paper aims to discuss the issues with this system. Design/methodology/approach A reflective optical fiber bundle hydrogen sensor was made up of an optical fiber bundle and a Pd0.75–Ag0.25 alloy hydrogen membrane. A combination of optical fiber light intensity measurements and the reference calculation method were used to extract the hydrogen concentration information from within the optical fiber, and the relationship between the hydrogen concentration changes and the reflective light intensity in the optical fiber was established. Findings The reflective optical fiber bundle hydrogen gas sensor based on a Pd–Ag alloy membrane was shown to provide an effective way to detect hydrogen concentrations. The experimental results showed that a 20-30-nm-thick Pd0.75–Ag0.25 alloy membrane could reach high hydrogen absorption and sensitivity. Key preparation parameters which included sputtering time and substrate temperature were used to prepare the hydrogen membrane during the DC sputtering process, and the reflectivity of the Pd–Ag alloy membrane was enough to meet the requirements of long life and high hydrogen sensitivity for the optical fiber hydrogen sensor. Originality/value This paper seeks to establish a foundation for optimizing and testing the performance of the Pd–Ag alloy hydrogen sensing membrane for an optical fiber bundle hydrogen sensor. To this end, the optimal thickness and key preparation parameters for the Pd–Ag alloy hydrogen sensing membrane were discussed. The results of this research have proved that the reflective optical fiber hydrogen sensor based on a Pd0.75–Ag0.25 alloy is an effective approach and precisely enough for hydrogen gas monitoring in practical engineering measurements.

Spatial Cycle Heating and Its PLC Control for Furnace

Aim at lower heating efficiency problem of furnace, the spatial cycle heating principle was brought forward and the testifying device was designed and fabricated. After the traditional heating principle was abstracted, modeled, narrated and analyzed, the obvious defect of lower heating efficiency was pointed out and analyzed in theory. The spatial cycle heating model was put forward to improve heating efficiency. And then different expressions aim at given models were deduced and compared. In theory, it was gained that the spatial cycle heating mode had a higher heating efficiency than traditional heating mode. Then a testifying experiment device was designed and constructed in terms of spatial cycle heating principle. PLC controller was employed to realize the closed-loop feedback control. Water temperature was the output of PLC control system. Temperature sensor was used to sample output and then to feedback to PLC controller. Heating resistors were considered as actuators. Furthermore, touch screen was also employed to control PLC controller and to dynamically display the water temperature. Experiment and its analytic results well demonstrated that the spatial cycle heating model could further improve the heating efficiency. Namely, spatial cycle heating principle is correct and effective and available for improving heating efficiency in furnace. It is very suitable for massive heating case such as winter heating.

The Design of Electronic Transformer Sophisticated Calibration System Based on FFT Algorithm

The present work investigated a sophisticated calibration system based on the FFT algorithm for electronic transformers. The structure and the characteristics of LabVIEW were introduced in detail, at the same time, and the detailed demonstration of the process of harmonic analysis was given via FFT based on LabVIEW. Through these methods, the disturbance of the frequency leakage and the noise could be reduced and the detecting accuracy of the harmonic analysis could be improved. Serials of the experiments and error analysis were given, and the simulation results have verified the effectiveness and practicability of the algorithm for the electronic transformer calibration system.