White light interferometry has been adopted to measure the distributed polarization coupling in high bireffingence thers A supoduminescent diode is adopted as the optical source in the white light interierometer To enlarge the reasorement range, the light beam in the scanning arm of the Micbelson interferometer is reflected three limes. Thus descanning range of the interferometer is doubled The full-width half-maximum spectrum of the SLD is 50nm, and cesenal wavelength is 1300mm. If the modal birefdngence of the I-IBF is 5

In this paper, white light interferometry has been used to measure the distributed polarization coupling in high birefringence fibres. Detailed theoretical analysis of the measurement accuracy of the testing system is presented. The main part is a Michelson interferometer with a scanning arm driven by a stepping motor. The minimum polarization coupling intensity detectable by this system is -77dB. The maximum fibre length that can be tested under this design is more than 1km, and the spatial resolution is better than 50mm. The influence of the opto-electro-mechanical devices on measurement accuracy has been analysed in order to improve the performance-to-cost ratio. This testing system can also be used in coherence division multiplexing optical fibre sensors.

This paper presented an optical intercormection multiple PC system connected by a ring network. This multiple PC system uses Linux Operating system, and the standard communication protocol of complying with Ethemet specification This paper studied the factors that influence the intereomection performance among multiple computers, including the effect of the buffer size of OLI on the bandwidth of network layer, and the effect of retransmission method on the performance. The results of ping-pong test show that optical fiber link is able to provide high-bandwidth and low-latency communication for a multi-PCs system. We found that the performance of the interoonneetion network can be improved by improving the interface match between the optical fiber link and computer bus input/oatput. Besides, the development of a chip to implement network interface and a part of network protocol, such as developing with FPGA device in this paper, could result in the higher performance of the interconnection.

The nmnerieal aperurc (NA3 of the double beam thterferometers (DBD can affect the acotrate measurement of surface profiles. Based on the double beam interference microscope imaging theory, the fringe spacing will vary wide nonlinearly with the increasing of numerical aperture. The double beam interferometers require oblique incidence illmnination, including Miehelson, Mirth and Linnik lypes. The intensity distribution of the ilumination across its slop is constant so the correction factor depends mainly on the NA in the Michelson and Linnik interferometers. The correction factor expression is derived in the Miehelson interferometer. The reference surface is a central obscnration in the beam, which will reduec the effective mnnerical aperture in the Miran interferometer. At the same mumerical aperatre, larger central obscuration has a much effect on the correction factor. The correction factor expression is determined by considering the influence of central obseuration and oblique incidence in the Mirau interferometer.

The hardware and the communimtion protocol of a statable optical ring have been designed. A hoxdware routing has been achieved on the network interface card to minimize data paeket communieation latency and a simplified communication protocol has been designed to reduce communication overheads. To reduce the data packet bilking probability and have a more efficient umgn of the data link layer bandwidth, a virtuaI multi channel transmimion mechanism has been achieved. The network supports a maximum of 16 virtual channds for each physical data link, Time slots can be dynamically assigned to each virtual channel. Zero wait time has been achieved for the switching between different virtual channels.