With Al2O3 and SiO2 as polishing medium, under different polishing conditions, e. g. with different pol-ishing pressure, polishing time and polishing fluid, the influences of polishing t reatment on the return loss of optical fiber connectors were investigated. The return loss of optical fiber connectors is 32 38 dB before polishing. The re-sult s show that dry polishing (i. e. no polishing fluid) with Al2O3 has less influence on return loss of optical fiber connectors, while dry polishing with SiO2 reduces return loss to about 20 dB because of the end-face of optical fiber contaminated. The wet polishing (i. e. using distilled water as polishing fluid) with Al2O3 or SiO2 can increase return loss to 45-50dB, but wet polishing with Al2O3 may produce optical fiber undercut depth of 80-140nm. Wet polis-hing with SiO2 should be preferentially selected for optical fiber connectors and polishing time should be cont rolled within 20-30s.

To obtain excellent performance optical fiber couplers, the structural difference of SiO2 in couplers with differ-ent manufacturing techniques was investigated. With 7402FT2IR infrared spectrometric analyzer, the infrared absorption spectrum of SiO2 in couplers at different drawing velocities was measured, and two characteristic peaks in the wavenumber range of 650 2000 cm-1 were observed. One characteristic peak is at about 943 cm-1, which is attributed to Si-O-Si bond asymmetric stretching vibration, the other is at about 773 cm-1, which is attributed to Si-O-Si bond symmetric stretching vibration. From the infrared spectrum, it is found that the intensity and wavenumber of the characteristic peaks are related to the manufacturing technique of couplers. The characteristic peak at about 943 cm-1 becomes steeper when increasing the drawing velocity. At the drawing velocity of 150μm/s, the distance between the two characteristic peaks is maximum, and then the optical fiber coupler has excellent performance, indicating that the performance of the optical fiber coupler has a close relationship with the wavenumber of the two characteristic peaks.

Anewalgorithm of the minimum zone method for evaluating form error-the valid characteristic point method with the rapidly contracted constraint zone-is put forward in this paper. Its mathematical model is established and its fundamentals are illustrated in detail, also its process of computation is described. The essence of this new algorithm is to search out the geometric characteristic parameters of the enveloping feather of the minimum zone, such as the normal vectors of the enveloping planes for flatness error and the coordinates of the center of the enveloping circle for roundness error. Based on searching for the characteristic points by applying the judging criteria of the minimum zone, the new algorithm sets up automatically a constraint zone of the geometric characteristic parameters of the enveloping feathers of the minimum zone and contracts it rapidly. This algorithm searches the geometric characteristic parameter of the enveloping feather of the minimum zone efficiently and can iterate the minimum value of the form error quickly. A large number of examples indicate that this new algorithm has many advantages such as a high proportion of success in first searching, fast calculation speed and few turns of iteration. Also, it can be applied to a computer-assisted instrumentation system on line.

Based on a series of tests, the chatter of temper rolling has been studied. It is shown that the temper rolling chatter is self-excited vibration and its cause is the rolling interface where partial fluid lubrication and viscous-slip co-exist.

Mill chatter is a notorio/ls condition in the high speed strip rolling process, having a behavior that is complex and changeful. During fieldwork to measure the vibration in high speed rolling mills, a frequency modulation phenomenon was identified, which had not beea reported in the strip rolling community. This article makes a theoretical investigation of the newly encountered phenomenon in the strip rolling process. According to an analysis of the mill roller bearings, the periodic change of stiffness of the bearings at the fixed load orientation, together with the periodic change o f the effective en-ors of the bearings, may ca use mnplimde mul frequency modulation, based on the theories of Fourier series and Bessel functions. The compmison between test results and theoretical analysis implies that the frequency modulation is caused by the effective en-ors of the mill roller bemings, that have 12 ripples on the internal ring.