排序方式: 共有22条查询结果,搜索用时 15 毫秒
1.
The improved range Doppler algorithm is proposed to abate the trade-off between resolutions and depth of focus in spectral domain optical coherence tomography.By considering the finite beam width and the shape of the wavefronts produced by the Gaussian beam,a physical diffraction model is presented to simulate the light propagation process in the sample.The two-dimensional processing of the spectrum data is decomposed into two one-dimensional processings of Stolt transform and matched filter.Experimental results show that image reconstruction can be achieved.The transverse and axial resolutions are both improved significantly,especially in the out-of-focus range,and the resolutions are almost equivalent throughout the entire region of interest. 相似文献
2.
为了同时获取样品的表面和深度信息,研究光学相干层析的成像原理,建立了基于光学相干层析技术的内窥系统,实现了旋转扫描成像,系统的工作波长为1 310 nm,工作带宽为80 nm.理论推导及计算机仿真得到了系统信噪比与干涉仪的分光比、反射率之间的关系并分析了理论分辨率和探测深度.提出外径为5 mm的内窥镜扫描探头,聚焦距离为12 mm,数值孔径NA为0.47,折射率分布常量A=0.218 7.利用微型电机驱动直角棱镜实现扫描,旋转速度为25 rpm,旋转一周得到640个采样点.采用多层盖玻片和洋葱表皮作为样品进行实验分析,得到了盖玻片和洋葱的图像,横向分辨率和纵向分辨率分别为10 μm和15 μm.结果表明,设计的光学相干层析内窥系统能够用于旋转扫描成像,获取更多的组织信息. 相似文献
3.
本文分析了自聚焦透镜的成象特性,提出了用薄透镜系统等效自聚焦透镜的方法,这种方法给用几何作图法和解析法求解物象关系带来了很大方便。 相似文献
4.
5.
6.
7.
8.
9.
数字式超声内窥成像系统(英文) 总被引:1,自引:1,他引:0
The development of a novel push-type ultrasonic endoscope is described in which probe rotation is accomplished by a small motor situated near the transducer. A digital FPGA-based ultrasound imaging system is implemented which uses coded excitation to increase the SNR and penetration depth, with probe rotation accomplished by a small motor situated near the transducer replacing the external motor and the long steel wire used in other ultrasonic endoscopes. The apparatus is tested continuously for 300 hours with no obvious problems. The coded excitation, digital quadrature demodulation imaging system can obtain ultrasonic images of higher quality and more information of the echo is preserved compared with the analog imaging system, because the analog digital conversion is moved to the first step of the signal processing.The digital imaging system possesses a higher SNR resulting in a sharp image. Locating the motor near the probe improves the consistency of rotational speed in comparison with external guide-wire rotation, and increases the image quality and life-span of these devices. 相似文献
10.