In the float glass defect inspection system based on machine vision, the common defects can be detected and classified correctly. However, the online glass ream inspection is still a problem to be solved, and the accuracy cannot fulfill the requirement of glass grading. As the glass ream is a rather slight optical distortion in most cases, it should be amplified so that it can be checked out easily. A Moiré method based on the theory of superposition shadow is proposed, which can magnify the distortion effectively without increasing the system complexity, and a STFT method is presented to analyze the distortion according to the characteristics of Moiré fringe pattern. With this method, the vision interference angle of glass ribbon can be calculated out accurately in real time, which makes it suitable for online glass ream inspection.
Based on the theory of gas molecular absorption spectrum, a transmission type gas cell based on cascaded GRIN lens has been designed. The gas cell is the kernel of the optical fiber gas sensor system. The system performance is relative to rationality of gas cell structure. By using GRIN lens couple in gas cell, we can solve the problems of optical discrete components. We use GRIN lens with pigtail fiber as collimating or focusing lens for transmission type of gas cell. To shorten sensor's size and length, and enhance sensor's sensitivity, we present a method by using cascaded GRIN Lens couples to compose a gas cell. With this method, the optical path length is increased and the detection sensitivity of the gas cell is greatly increased. This transmission type of gas cell based on cascaded GRIN lens couples have been applied to our system of absorption spectrum optical fiber gas sensors. We designed and manufactured a gas cell with cascaded GRIN lens couples. Experimental results show that transmission gas cell based on cascaded GRIN lens couples has a good detecting effect.
Design of an embedded optical fiber micro-displacement measurement system is presented. It consists of an optical fiber displacement sensor, a signal pre-processing unit and an embedded microprocessor unit of ADuC812. The displacement sensor is a reflective intensity-modulated optical fiber bundle sensor with two paths of optical signal output, so influences of light resource fluctuation and other common interferences such as external environment and fiber loss are reduced. The signal pre-processing unit consists of several functional circuits, such as optical-electrical transducer, pre-amplification unit, band-pass filter and phase sensitive detection circuit, and is used to transform the two paths of optical signals mentioned above into two paths of electrical signals. ADuC812 is an advanced embedded microprocessor module with high performance and low price. In this application, it is used to accomplish functions of two paths of signals sampling, signals dividing and signal nonlinear processing, and finally output an analog voltage in proportion with the measured displacement. By introducing the embedded microprocessor module of ADuC812, the measurement performance and intelligent extent of the micro-displacement measurement system can be improved, resulting in the wide applications in advanced manufacturing and testing.
The computer- or microprocessor-based signal processing technology is one of the demodulation and processing methods capable of suppressing noise interference and enhancing signal-to-noise ratio. In this paper, the technology of software filtering and demodulation based on wavelet transform is presented. According to the features of band- pass and time-frequency domain localization of wavelet transform, a linear combine wavelet transform is used to approach an ideal narrow-band filter, and the designed filter has a fine filtering character. It provides a more convenient method for signal demodulation analysis and multi-pass-band components filtering in engineering signal processing. It has been used in the case of optical current transformer and can be developed to other signal processing applications.