Influence of high temperatures on a fiber-optic probe for temperature measurement

The use of optical fiber in a temperature probe or sensor for optical pyrometry in the 100-1000 °C range is affected by the low thermal stability of classical fibers. We have studied the different sources of perturbations induced by exposure to high temperature. Two specific fibers especially suited for a high-temperature environment were tested and compared. Low (100 °C/min) and very fast (100 °C/s) fiber heating was performed to evaluate its influence on the guided flux and the induced error on temperature measurement. The metallic-coated fiber shows a reproducible temperature error that can be predicted. This important result permits the development of an uncooled fiber probe for temperature monitoring in high-temperature environments such as aerospace engines.     

A dynamic technique for measuring normal spectral emissivity of electrically conducting solids at high temperatures with a high-speed spatial scanning pyrometer

A dynamic (subsecond) technique is described for measuring normal spectral emissivity of electrically conducting solids at high temperatures, primarily in the range 1800 K up to near their melting point. The basic method involves resistively heating a tubular specimen from ambient temperature through the temperature range of interest in less than 1 s by passing an electrical current pulse through it, while using a high-speed spatial scanning pyrometer to measure spectral radiance temperatures along a 25-mm length on the specimen. This portion of the specimen includes a small rectangular hole that approximates a blackbody cavity. Measurements of spectral radiance temperature of the specimen surface as well as specimen true temperature enable the determination of the normal spectral emissivity of the surface via Planck's law. The applicability of the technique is demonstrated by measurements performed on molybdenum in the range 1900–2850 K.     

利用平面止推轴系研制高精度定心仪

为了减小中心偏对光学仪器质量的影响,研制了一种利用平面止推轴系为基础的高精度定心仪。该定心仪测量精度:角晃动≤2″,转台主轴径向晃动≤1μm。利用该仪器对多组准直物镜进行了装调和中心偏测量,取得了较为满意的结果。在WYKO数字干涉仪上对装调好的准直物镜的光学性能进行了检测,测得波面误差的峰谷值(PV)为0.143λ,均方根误差为(1/50)λ,斯特列尔比(Strehl)已达到98%。检测结果表明,利用该仪器装调的准直物镜可以达到很高的精度。     

The transient regime of a multiwavelength pyrometer

The transient operation of a new multiwavelength pyrometer based on a dispersing prism and a Si photodiode array is presented. After calibration, transient tests were performed using a tungsten strip lamp, supplied by a current pulse of 0.3-s duration. Measurements were carried out with a data acquisition system consisting of a FET multiplexer, a DVM (14 bit, 100 kHz), and a buffer memory (64 kbytes). Pyrometer signals are processed off-line, and temperature vs time is displayed. With the present arrangement, temperature measurements at 20 wavelengths may be performed with 200s resolution. Faster measurements are possible with a reduced number of channels.Paper presented at the Third Workshop on Subsecond Thermophysics, September 17–18, 1992, Graz, Austria.Deceased     

The measurement of low temperatures

Temperature measurement is almost always ancillary to some other measurement in bulk liquid handling and may therefore be added as something of an after-thought. Care over some features of the installation, however, is essential if good temperature measurements are to be made. This paper attempts to draw attention to some of the points to be considered and to give some examples of actual applications.Some fundamental concepts are common to all types of temperature measurement, and these are discussed briefly.     

IAN-3 measuring instrument for the precision measurement of high voltages in X-ray apparatus

The IAN-3 measuring instrument for accurate measurements of anode voltages with ripples in x-ray apparatus in the 40–125 kV range has been developed. The measuring instrument, the method of adjusting and calibrating it, and the results of the calibration are considered. The measurement error does not exceed 0.25%. The IAN-3 measuring instrument can be used to calibrate radiation-type kilovoltmeters and for adjusting medical x-ray diagnostic equipment. Translated from Izmeritel'naya Tekhnika, No. 2, pp. 49–51, February, 1998.     

A simple,inexpensive high resolution digital thermometer for measurement of low temperatures

A simple high resolution digital thermometer is described. The temperature measurement efficiency in the temperature range 77 to 300 K has been found to be better than ± 100 μK.     

Design concept for a new ESCA instrument

In surface science, an important new requirement is imposed upon ESCA instruments, the ultra high vacuum compatibility. In order to keep the measurement-cycle of such an instrument as short as possible, it has to fulfill two conditions:

1.

1. The time needed to introduce a new sample into the vacuum system should be as short as possible.     

直流高压标准装置国际近况

简单介绍电磁计量领域关键比对数据库中直流高压参数标准装置-直流高压分压器的原理,分析了电阻发热、电晕放电以及绝缘支架漏电对直流高压分压器的影响,归纳总结目前国际上先进计量机构的直流高压标准装置的结构型式以及在校准时引入的不确定度来源。给出了直流分压器达到10-6量级的必要条件。     

Measurements of thermophysical properties of nickel with a new highly sensitive pyrometer

A new, sensitive, and fast (response time, 100 ns) pyrometer used for the measurement of temperature in pulse heating experiments is described. The monochromatic instrument may use two detectors, namely, a Si diode and an InGaAs diode. Since monochromatic pyrometers usually are self-calibrated with the plateau of the melting transition of the investigated metal, a high sensitivity is desirable. The pyrometer is sensitive down to 1000 K and may be used at the melting plateau of copper, a reference point on the International Temperature Scale of 1990. A wide temperature range in a single measurement is possible with the use of a fast operational amplifier with linear and logarithmic outputs. Electrical resistivity, heat capacity, and enthalpy of nickel were measured in the temperature range 1500 to 2200 K using a fast pulse heating technique.Paper presented at the Third Workshop on Subsecond Thermophysics, September 17–18, 1992, Graz, Austria.     

A virtual instrument for measurement of flicker

All types of fluctuations of the rms voltage in power systems may be assessed by using a “flickermeter” which complies with the specifications given in IEC-EN 60868. In this paper, a digital flickermeter is presented based on the implementation in the frequency domain of the weighting filter block of the eye-brain simulation chain. The virtual instrument, implemented with an acquisition board inserted into a PC and with a software developed with the LabView tools, samples the voltage and furnishes the instantaneous flicker level and other severity coefficients. Results of simulated and actual data are reported to validate the performance of the developed flickermeter