Design electrically calibrated pyroelectric radiometer

Abstract

The electrically calibrated pyroelectric radiometer (ECPR) has been constructed. The system is composed of a nichrome‐film‐coated LiTaO₃ pyroelectric detector, signal conditioning circuits, a heating circuit, a chopper system, and a microprocessor for power computation and synchronization as well as power display. It has been tested and compared with a commercial optical power meter with good consistence. Design considerations of the detector are discussed.     

Calibration of a pyroelectric detector at 10.6 microm with the National Institute of Standards and Technology high-accuracy cryogenic radiometer

The National Institute of Standards and Technology (NIST) is establishing an infrared detector calibration facility to improve radiometric standards at infrared wavelengths. The absolute response of the cryogenic bolometer that serves as the transfer standard for this facility is being linked to the NIST high- accuracy cryogenic radiometer (HACR) at a few laser wavelengths. At the 10.6-microm CO(2) laser line, this link is being established through a pyroelectric detector that has been calibrated against the HACR. We describe the apparatus, methods, and uncertainties for the calibration of this pyroelectric detector.     

常温高性能PMN-PMS-PZT热释电材料

研究了组分改变对PMN-PMS-PZT(铌锰酸铅-锑锰酸铅-锆钛酸铅)热释电陶瓷材料的相组成、介电性能、热释电性能等方面的影响,并对实验结果进行了分析.实验结果表明:通过改变材料Zr/Ti的比例,在陶瓷介电常数εr和介电损耗tanδ变化不大的情况下,使得热释电系数的峰值向室温附近移动;在Zr/Ti=95/5时,常温(28℃)下介电常数占εr=228.5、介电损耗tanδ=0.23%,热释电系数P=25.5×10-4C/m2℃,探测率优值FD=47.3×10-5Pa-1/2,此类材料符合制作热释电红外探测器的要求.     

A spherical radiometer

A theoretical analysis is performed of a radiation detector constructed in the form of a spherical cavity within which a filament heater is located, with an externally mounted thermopile.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 36, No. 5, pp. 896–900, May, 1979.     

Piezo- and pyroelectric microscopy

In recent decades piezo- and pyroelectricity found application in yet another important field of research. A number of methods have been developed which employ these properties to investigate the micro- and macroscopic polarization of materials. Advances in piezo- and pyroelectric imaging enabled researchers to examine the polarization distribution of a sample with unprecedented detail. This review attempts to inform the general reader about some of those experimental techniques and their findings.     

Materials for pyroelectric detectors

A brief review is given of the use of pyroelectric materials in single element and arrays of infra-red detectors.     

Fiberoptic pyroelectric radiation-temperature meter

The article describes the design and characteristics of a fiberoptic pyroelectric radiation-temperature meter of measuring the local temperatures of various objects in almost inaccessible places. A distinguishing feature of the meter is that it has a flexible fiberoptic cable, which makes it possible to measure the temperature of 0.5-2 mm-diameter portions in cavities with a complex configuration.Translated from Izmeritel,naya Tekhnika, No. 6, pp. 35–37, June, 1994.     

Novel pyroelectric sensor materials

Ceramic compositions of barium strontium titanium oxide (BSTO) have been formulated for applications as pyroelectric sensor materials. The material has been fabricated in tape-cast and thin film forms. In general, the materials demonstrated high pyroelectric coefficients (p) accompanied with low dielectric constant and low dissipation factor. The compositions of the tape-cast and thin film specimens examined in this paper include a well-known commercially adopted Ba_0.64Sr_0.36TiO₃ as well as a composition suggested in the literature, and a patented composition with the addition of MgO to BSTO is investigated. Doping BSTO with MgO has been shown to reduce the dielectric constant and loss tangent (over a very wide frequency range from 100 Hz-10 GHz) of the material and thereby increase the pyroelectric figure of merit. This article will discuss the processing, material characterization, pyroelectric coefficient, and pyroelectric figure-of-merit of the above mentioned BSTO compositions.     

Domain-engineered lithium niobate as a medium for an integrated solid-state two-dimensional color laser scanning system

A recently proposed alternative to conventional prism-type electro-optic solid-state deflectors is the single interface deflector. Whereas these deflectors are comparable in performance to prism-type deflectors, they are far simpler in construction. This simplicity obviously has the advantages that it reduces fabrication time and cost and allows for easier optimization. Less obviously, but more advantageously, the simplified geometry provides, for the first time to our knowledge, the ability to achieve a completely solid-state two-dimensional beam deflector. We also detail how the two-dimensional deflector can be further augmented by the addition of intensity and color switching to the device.     

Frequency response of multilayer pyroelectric sensors

The pyroelectric response of the multilayer system consisting of the front surroundings, the pyroelectric element, the intermediate layer, and the back surroundings is calculated. The general expression and simple relations are obtained between main geometric and thermophysical parameters of the system under consideration and characteristics of the pyroelectric response in a large variety of configurations of pyroelectric sensors, such as detectors with the pyroelectric element in a gas, detectors without air gap as well as detectors with air gap between the element and the substrate, and detectors in immersion systems, etc. In particular, it is shown that, for the detectors with air gap, the wide flat part of the frequency response appears with any properties of substrate if the double thermal resistance of the air gap exceed that of the pyroelectric element, whereas for the detectors without air gap it appears only if the substrate has relatively large complex thermal conductivity.     

PbSc0.5Ta0.5O3热释电材料及其红外探测器列阵

热释电红外探测器具有探测波长范围广、室温工作、无需致冷等优点。近年来，工作于介电方式下的PbSc0.5Ta0.5O3(PST)热释电材料由于具有热释电系数大，热释电探测优值高等特点，成为热释电应用研究的热点之一。本文综述了目前PST热释电陶瓷材料的介电，热释电性能及其探测器列阵的发展。由于小型化的要求，PST薄膜亦倍受关注，因此本文还对目前PST热释电薄膜的制备方法，薄膜的热释电、介电性能及薄膜型探测器结构和发展进行了概述。     

Characterization of the length-modulated radiometer

The development of the length-modulated radiometer (LMR), which is a new type of correlation radiometer for remote sounding, is described. Factors that affect the performance of the LMR are identified and, whenever possible, are minimized. Laboratory measurements of the radiometric response of a LMR filled with carbon monoxide are presented and compared with theoretical calculations. An analysis of the sources of error in these measurements and calculations is presented.     

Theory of the radiometer effect

A study is reported of the origin of the force exerted on a plate by a Knudsen gas.     

Cyclic energy harvesting from pyroelectric materials

A method of continuously harvesting energy from pyroelectric materials is demonstrated using an innovative cyclic heating scheme. In traditional pyroelectric energy harvesting methods, static heating sources are used, and most of the available energy has to be harvested at once. A cyclic heating system is developed such that the temperature varies between hot and cold regions. Although the energy harvested during each period of the heating cycle is small, the accumulated total energy over time may exceed traditional methods. Three materials are studied: a commonly available soft lead zirconate titanate (PZT), a pre-stressed PZT composite, and single-crystal PMN-30PT. Radiation heating and natural cooling are used such that, at smaller cyclic frequencies, the temporal rate of change in temperature is large enough to produce high power densities. The maximum power density of 8.64 μW/cm3 is generated with a PMN-30PT single crystal at an angular velocity of 0.64 rad/s with a rate of 8.5°C/s. The pre-stressed PZT composite generated a power density of 6.31 μW/cm(3), which is 40% larger than the density of 4.48 μW/cm3 obtained from standard PZT.     

Polarization processes in pyroelectric Langmuir-Blodgett films

We report on an investigation into the origins of the pyroelectric effect in some alternate layer Langmuir-Blodgett (LB) films. The pyroelectric coefficient is measured as a function of temperature and of the thermal expansion coefficient of the substrate on which the film is deposited; these experiments enable a partial separation of the primary and secondary pyroelectric effects. The results indicate that thermal expansion of the substrate tends to reduce the total pyroelectric coefficient through a piezoelectrically induced effect. At low temperatures, the film behaves like a “free crystal”, and the pyroelectric coefficient shows a power law dependence on temperature. However, at temperatures above 240 K, the substrate- induced effect becomes dominant. The results are used to deduce methods by which the pyroelectric response of the LB film devices might be improved.     

Dielectric and pyroelectric properties of triglycerol-gelatin films

The dielectric and pyroelectric properties of triglycerol-gelatin thick films were studied as a function of temperature and frequency. The films exhibited a strong dispersion in the dielectric permittivity accompanied by a high dielectric loss near room temperature. The pyroelectric current measured by the static Byer-Roundy method is heavily dominated by the thermally stimulated currents. Measurements performed on prepoled samples using the dynamic technique of A.G. Chynoweth (1956) clearly proved the presence of a true, reversible pyroelectric response in the examined films. The value of the pyroelectric coefficient of the films was found to be comparable to that of polyvinylidene fluoride (PVDF)     

A highly sensitive absolute cavity radiometer

A model of a highly sensitive cavity radiometer with an original construction of the thermal indication unit, which enables the error in carrying out the electrical substitution procedure to be reduced considerably, is described. The main metrological characteristics of the standard radiometer obtained using the model are presented. Translated from Izmeritel'naya Tekhnika, No. 8, pp. 42–45, August, 1999.