A two-dimensional (2D) simple structured ultranarrow-band metamaterial perfect absorber (MPA) with nanocylindrical array is studied both theoretically and experimentally. Using a dielectric 2D cylindrical array as the top grating layer of the MPA, an ultranarrow nonpolarizing absorption peak at normal incidence is obtained. Furthermore, we use the same dielectric material to simplify the topology of the ultranarrow-band MPA, and the number of film layers in the MPA is reduced from 3 to 1. By optimizing its structural parameters and metal substrate, the highest ultranarrow nonpolarizing absorption peak that approaches 1 at normal incidence is obtained. To analyze the absorption physical mechanism, the heat power density distributions of the optimized MPA are simulated to see where the incident light is absorbed. Moreover, numerical simulation results show that the main transverse-electric absorption peak of the optimized MPA is insensitive to the incident angle, and the main transverse magnetic absorption peak is sensitive to the incident angle. Finally, we fabricate an MPA sample with dielectric nanocylindrical array and measure its absorption spectra to make a further comparison. The experimental data are consistent with the theoretical ones. This method might be helpful to reduce the manufacture difficulty and cost of the ultranarrow-band MPAs and also to promote the development of applications of the ultranarrow-band MPAs.
The spectral emissivity and transmissivity of zinc sulphide (ZnS) infrared windows in the spectral region from 2 to 12 μm and temperature range from 20 to 700°C is measured by a facility built at the Harbin Institute of Technology (HIT). The facility is based on the integrating-sphere reflectometry. Measurements have been performed on two samples made of ZnS. The results measured at 20°C are in good agreement with those obtained by the method of radiant energy comparison using a Fourier transform infrared spectrometer. Emissivity measurements performed with this facility present an uncertainty of 5.5% (cover factor=2 ).
According to radiation temperature measurement theory, the key of temperature measurement is to choose the appropriate temperature model, which depends on the type of measured material. So how to identify the material type is significant to measure its surface temperature. Different materials have different spectral characters at the same temperature. In this paper, a method based on spectrum analysis is proposed to identify material. The spectrum of four kinds of materials is measured using Fourier transform infrared spectrometer (FTIR) at the same temperature 873K. The peak values extracted from each spectrum are used to train the identification algorithm. Then one material is chosen from the measured materials to verify the identification algorithm if the type of material can be identified. The experimental results suggest that the new method based on spectrum analyses can accurately identify the type of material.
The emissivity is a key parameter to measure the surface temperature of materials in the radiation thermometry. In this paper, the surface emissivity of metallic substrates is measured by the multi-wavelength emissivity measurement apparatus developed by the Harbin Institute of Technology (HIT). The measuring principle of this apparatus is based on the energy comparison. Several radiation thermometers, whose emissivity coefficients corrected by the measured emissivity from this apparatus, are used to measure the surface temperature of stainless steel substrates. The temperature values measured by means of radiation thermometry are compared to those measured by means of contact thermometry. The relative error between the two means is less than 2% at temperatures from 700K to 1300K, it suggests that the emissivity of stainless steel substrate measured by the multi-wavelength emissivity measurement apparatus are accurate and reliable. Emissivity measurements performed with this apparatus present an uncertainty of 5.9% (cover factor=2).
The absorption spectra of ethylene (C2H4) located at v5+v9 band near 1626nm involve some strong peaks that are suitable for trace gas concentration detection. They are interference free from other abundant molecules that are normally present in the atmosphere. An ethylene analysis system has been developed based on the tunable diode laser absorption spectroscopy. The high resolution transmission of ethylene near 1626nm has been measured by this system under different concentration. The severe overlapping between neighboring spectral lines of ethylene is observed and they cannot be separated with each other easily under atmospheric pressure and room temperature, so a multi-peaks spectrum recognition method is proposed to separate the ethylene spectrum from other interference gas while the ethylene concentration is ultra low. A mixture of high concentration methane, low concentration ethylene with air is used to evaluate the recognition efficiency. The result shows that the ethylene line can be abstract from strong background interference using multi-peaks spectrum recognition method and the accuracy of concentration measurement can reach about 5% comparing with a mass flow meter.
The application of Quad Flat Pack (QFP) and Ball Grid Array (BGA) technology in manufacturing of advanced electronic products has been grown significantly during the past several years. QFP and BGA has several advantages over traditional packaging technology in terms of smaller package area, higher I/Os, higher assembly yield, and so on. However, some potential problems of bridge among solder joints in QFP and creep-fatigue failure of solder joints in BGA serving occurs and often results in the failure of products. It has been found that both the bridge in QFP and fatigue failure of solder joints in BGA highly depends on the shape of solder joints. So, in this paper, the mathematical models of simulating the formation of solder joints in QFP and BGA are built based on minimum energy theorem, and the shape of solder joints are predicted. According to the predicted shape, the bridge mechanism in solder joints in QFP and the fatigue failure of solder joints in BGA is investigated.
A high accuracy optical bistable temperature sensor was proposed and proved experimentally by using a fiber-optic Mach-Zehnder interferometer combined with an electro-optic bistable device.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.