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Li Z.,Tianjin University | Li Z.,Suzhou Optoring Technology Co. | Meng Z.,Tianjin University | Meng Z.,Suzhou Optoring Technology Co. | And 4 more authors.
Optics Letters | Year: 2012

We present a novel method for improving the spatial resolution and amplitude accuracy of distributed polarization cross-talk measurements in a polarization maintaining (PM) fiber against its birefringence dispersion. We show that the broadening of measured polarization cross-talk peaks caused by birefringence dispersion can be restored by simply multiplying the measurement data with a compensation function. The birefringence dispersion variable in the function can be obtained by finding the widths of measured cross-talk envelopes at known distances along the fiber. We demonstrate that this method can effectively improve spatial resolution and amplitude accuracy of the space-resolved polarization cross-talk measurements of long PM fibers. © 2012 Optical Society of America.

Li Z.,Jiangnan University | Li Z.,Tianjin University | Li Z.,Suzhou Optoring Technology Co. | Yao S.,Tianjin University | And 2 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2014

To solve the problem of the restricted accuracy of the polarization maintaining fiber optic gyroscope (PM-FOG), whose static parameters are influenced by its optical path polarization crosstalk errors, from the view of practical applications, the mechanism of polarization crosstalk errors in light path caused by unsatisfactory optical devices and fused points' axis angle errors is studied. Based on the Jones matrix and correlation matrix, the PM fiber's birefringence variable which varies with temperature change is introduced, the optical transmission model of PM-FOG in variable temperature fields is built, and the effect of polarization crosstalk errors on PM-FOG zero drift and random walk in variable temperature fields is analyzed and estimated. Meanwhile, the related experiments are carried out to study the effect of fiber coils polarization crosstalk on its static parameters in variable temperature fields. The experimental results and analysis results of model are in agreement, which shows that the model is reasonable. ©, 2014, Chinese Optical Society. All right reserved.

Shi B.,Tianjin University | Shi B.,Tianjin Polytechnic University | Meng Z.,Tianjin University | Meng Z.,Suzhou Optoring Technology Co. | And 2 more authors.
Journal of Optics (United Kingdom) | Year: 2013

We present a Monte Carlo model for optical coherence tomography (OCT) imaging of human tooth. The model is implemented by combining the simulation of a Gaussian beam with simulation for photon propagation in a two-layer human tooth model with non-parallel surfaces through a Monte Carlo method. The geometry and the optical parameters of the human tooth model are chosen on the basis of the experimental OCT images. The results show that the simulated OCT images are qualitatively consistent with the experimental ones. Using the model, we demonstrate the following: firstly, two types of photons contribute to the information of morphological features and noise in the OCT image of a human tooth, respectively. Secondly, the critical imaging depth of the tooth model is obtained, and it is found to decrease significantly with increasing mineral loss, simulated as different enamel scattering coefficients. Finally, the best focus position is located below and close to the dental surface by analysis of the effect of focus positions on the OCT signal and critical imaging depth. We anticipate that this modeling will become a powerful and accurate tool for a preliminary numerical study of the OCT technique on diseases of dental hard tissue in human teeth. © 2013 IOP Publishing Ltd.

Meng Z.,Tianjin University | Meng Z.,Suzhou Optoring Technology Co. Ltd | Yao X.S.,Tianjin University | Li Z.,Tianjin University | And 6 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

We present several advanced techniques for evaluating the quality of fiber gyro coils, including characterizing the temperature and vibration transient characteristics of fiber coils, monitoring polarization-maintaining fiber (PMF) coil winding quality using distributed polarization crosstalk analyzer (DPXA) during production, and the defect detection of fiber coil using optical coherence tomography (OCT). To the best of authors' knowledge, this is the first report of using OCT for fiber coil inspection. The use of these new techniques can effectively improve and guarantee the quality of the fiber gyro coils. © 2012 SPIE.

Shi B.,Tianjin University | Shi B.,Tianjin Polytechnic University | Meng Z.,Tianjin University | Meng Z.,Suzhou Optoring Technology Co. | And 2 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2014

We study non-distorted imaging depths of optical coherence tomography (OCT) system in different tooth tissues based on Monte Carlo modeling of tooth OCT imaging. Two-dimensional simulated OCT images of single tooth enamel, dentin and two-layer tooth tissues are obtained by simulating the incident Gaussian beam and light propagation in dental tissues. The simulated images exhibit qualitative agreement with the experimental ones. The average non-distorted imaging depths of three kinds of dental tissue structure are gained through the analysis of one-dimension OCT signals corresponding to the simulated OCT images. It is indicated that the non-distorted imaging depths of the OCT system in dental tissues are 150~2400 μm, the non-distorted imaging depth of the enamel is much greater than that of the dentin. The results have certain reference value for the judgment on effective tissue structure information in experimental OCT images.

Wang L.,Tianjin University | Yao X.,Tianjin University | Yao X.,Suzhou Optoring Technology Co. | Meng Z.,Tianjin University | And 7 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2013

With imaging depth increasing, the local contrast in the optical coherence tomography (OCT) image of object decreases, which makes it difficult to observe the internal features of object. An adaptive multi-scale Retinex (AMSR) algorithm is proposed for OCT attenuation compensation. It automatically adjust the weights of Retinex enhanced images with different scales according to the mean values of absolute differences between Retinex enhanced image with large scale and Retinex enhanced images with other small scales. This method is verified by a human fingertip OCT image and skin OCT image that AMSR can effectively compensate the light attenuation in the original OCT image, and enhance the local contrast of structure details within object. Furthermore, comparing with the original OCT image, the visual contrast measure (VCM) of the AMSR enhanced image increases 5740. This method is useful to improve the visualization of structures inside object.

General Photonics Corporation and SUZHOU OPTORING TECHNOLOGY Co. | Date: 2014-06-02

Imaging devices and processing techniques based on imaging information along the depth direction in an optical coherent tomography (OCT) image are disclosed to enhance observed morphological features. The methods and systems obtain different OCT images of the target object under different reference path lengths, process the different OCT images to obtain a derivative with respect to the signal path length of image information of the different images, and processing the derivative to extract improved image information of the target object. The derivatives may be in a form related to a gradient value of the normalized OCT image intensity, or an attenuation coefficient.

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