Analysis of Inter-Modulation Interference for MM-Wave Receiver

The problem of inter-modulation interference is an important problem in super-heterodyne receiver. In the past, the analysis about it was carried out for the lower frequency communication for example the short wave communication. In this paper, the analysis about inter-modulation interference and the output signal of frequency mixer will be carried out for MM-wave communication according to the features of MM-wave multi-channel communication. Then, the corresponding methods to reduce or avoid mixer output interference and inter-modulation interference are recommended.     

Variable wavelength interferometry of birefringent retarders

A new interferometric procedure is proposed for testing birefringent retarders. The procedure uses monochromatic light with a continuously variable wavelength and two parallel pointer lines localized at a distance from each other in the fringe interference field of a double-refracting interferometer. The zero-order fringe of the empty interference field is brought into coincidence with one pointer line, and higher-order interference fringes displaced by an object under study are next brought into consecutive coincidence with the other pointer line as the wavelength of the monochromatic light is continuously varied.     

Differential thickness measurement using a polarization interferometer

A method for measuring the differential thickness of a thin film using a polarization interferometer is described. Theoretical estimation shows that the measurement error is less than 0.1%. Experiments performed on a PZT sample indicate high sensitivity and excellent linearity of the system. PZT expansions ranging from 300 nm to less than 1 nm could be measured with a precision better than 0.1 nm.     

Optical characteristics of an afterglow extracted from an inductively coupled plasma

An inductively coupled plasma is extracted into a quartz vacuum chamber through an orifice to observe optical characteristics of the extracted afterglow. The Mach disk, the barrel shock and the zone of silence, which are familiar in supersonic molecular beam experiments with neutral gases, are clearly observed. Axial profiles of the emission of various lines are measured with a photodiode array spectrometer. Intensities of ionic lines as well as atomic lines are stronger at the Mach disk than in the zone of silence. The location of the Mach disk with varying chamber presure is in conformity with an experimental equation obtained in supersonic molecular beam experiments.     

High-power laser interference lithography process on photoresist: Effect of laser fluence and polarisation

High throughput and low cost fabrication techniques in the sub-micrometer scale are attractive for the industry. Laser interference lithography (LIL) is a promising technique that can produce one, two and three-dimensional periodical patterns over large areas. In this work, two- and four-beam laser interference lithography systems are implemented to produce respectively one- and two-dimensional periodical patterns. A high-power single pulse of ∼8 ns is used as exposure process. The optimum exposure dose for a good feature patterning in a 600 nm layer of AZ-1505 photoresist deposited on silicon wafers is studied. The best aspect ratio is found for a laser fluence of 20 mJ/cm². A method to control the width of the sub-micrometer structures based on controlling the resist thickness and the laser fluence is proposed.     

Inverse problem of fracture mechanics for a disk fitted onto a rotating shaft

A plane problem of fracture mechanics for a circular disk fitted onto a rotating shaft is considered. The disk is assumed to be fitted tightly onto the shaft, and there are N randomly located straight-line cracks of length 2l_k (k = 1, 2, ..., N) near the inner surface of the disk. The interference between the disk and the rotating shaft, providing minimization of fracture parameters (stress intensity factor) of the disk, is theoretically studied on the basis of the minimax criterion. A closed system of algebraic equations is constructed, which allows the problem of optimal design to be solved. A simplified method of minimization of disk fracture parameters is considered. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 201–209, July–August, 2009.     

Individual and joint influence of second- and third-order dispersion on the transmission quality in the presence of coherent interference

The shape of a resulting pulse (coherent interference superimposed to Gaussian pulse) along the linear optical fiber is determined by using attained analytical expressions. These analytical expressions enable the investigation of the influence of arbitrary dispersion order on pulse propagation. Individual and joint influence of second- and third-order dispersion on the transmission quality is examined in this paper. Pulse shape, eye diagram and bit error rate (BER) are used to represent in the best manner the above-mentioned influences.     

火焰原子吸收法测定焊丝BHD60中Cr

通过反复试验,建立了一种快速排除W、Mo和V对Cr的干扰后用火焰原子吸收测定焊丝BHD60中Cr的方法.通过用相近标准样品验证,方法的准确性和重复性均满足GB/T 223.11 - 2008中铬的容量法中提供的再现性限(R)和重复性限(r),方法操作简便,结果可靠,分析速度快,尤其适合于批量分析.