Microwave Type Bolometer for Submillimeter Wave Measurements

An approach to the problem of submillimeter wave measurement through the extension of microwave techniques has led to the development of a submillimeter bolometer with the sensitivity requisite to calibration with a thermal source. The sensor employs conventional components, horn, waveguide and coaxial line, with a novel coax-to-guide transition consisting of part of the bolometer element, the rest of which serves as a center conductor of the coaxial lines. The entire set of submillimeter components is contained in a 1/4-inch block of metal. Fundamental problems of detection in this band are discussed with application to the sensor. Calibration techniques and data taken with the instrument are reported.     

原子发射光谱双谱线测温技术

温度是一个重要的物理量,是工业生产和化爆试验中需要测量的重要参数,它将有效指导各种产品的设计和生产。在一些温度高、变化快,测量环境恶劣的场合,原子发射光谱双谱线法得到了成功的应用。该文介绍了原子发射光谱双谱线测温法的测温原理以及其在各方面的应用,最后分析了应用原子发射光谱双谱线测温法应注意的问题,并对该方法进行了展望。     

Quantum effects in cyclotron resonance using a CW hydrogen-cyanide laser

A submillimeter resonance spectrometer has been developed, which employs a molecular gas laser as a source of radiation. Cyclotron resonance measurements of the quantum effects in the valence bands in germanium were taken with the use of a CW HCN laser. It is shown that the use of CW instead of pulsed lasers helps to avoid resonance line broadening and permits extensive quantitative results suitable for theoretical analysis to be recorded. The purpose of pursuing these methods to acquire detailed data on quantum transitions in semiconductors is to collect the information needed to design and develop a tunable submillimeter maser based on cyclotron resonance transitions.     

Submillimeter BWO spectroscopy of solids

The potentialities of submillimeter spectroscopy (3–30 cm^?1) based on backward wave oscillators for studying solids are discussed. The scope of the research on this problem made at the Institute of General Physics of the USSR Academy of Sciences is outlined.     

Submillimeter-wavelength heterodyne spectroscopy and remote sensingof the upper atmosphere

The use of remote sensing based on heterodyne spectroscopy at submillimeter wavelengths to monitor changes and study processes in the Earth's upper atmosphere is discussed. An experiment for this purpose, performing measurements in spectral bands near 63, 183, and 205 GHz and now operational on the NASA Upper Atmosphere Research Satellite (UARS), is described. An experiment which includes measurements in spectral bands up to 2.5 THz, being studied for future Earth observation systems, is briefly discussed     

Millimeter-Wave and Submillimeter-Wave Imaging for Security and Surveillance

Passive equipments operating in the 30-300 GHz (millimeter wave) band are compared to those in the 300 GHz-3 THz (submillimeter band). Equipments operating in the submillimeter band can measure distance and also spectral information and have been used to address new opportunities in security. Solid state spectral information is available in the submillimeter region making it possible to identify materials, whereas in millimeter region bulk optical properties determine the image contrast. The optical properties in the region from 30 GHz to 3 THz are discussed for some typical inorganic and organic solids. In the millimeter-wave region of the spectrum, obscurants such as poor weather, dust, and smoke can be penetrated and useful imagery generated for surveillance. In the 30 GHz-3 THz region dielectrics such as plastic and cloth are also transparent and the detection of contraband hidden under clothing is possible. A passive millimeter-wave imaging concept based on a folded Schmidt camera has been developed and applied to poor weather navigation and security. The optical design uses a rotating mirror and is folded using polarization techniques. The design is very well corrected over a wide field of view making it ideal for surveillance and security. This produces a relatively compact imager which minimizes the receiver count.     

Millimeter Waveband Open Resonator for Low Temperature Magnetospectroscopy

Investigation of key electrodynamical properties of open resonator intended for operating in millimeter and submillimeter wavelength range Electron Spin Resonance (ESR) spectroscopy are represented. The resonator is designed for study of specimens cooled up to cryogenic temperatures. Methodical features of physical experiment for such non-cooled resonator together with continuous flow cryostat are discussed. Results of test ESR-measurement demonstrating virtues of the resonator structure are given.     

Submillimeter-wave emission assignments for 1,1-difluoroethylene

Many of the known submillimeter wave emissions of 1,1-difluoroethylene are assigned by using new data from infrared diode laser heterodyne spectroscopy. Six new submillimeter lines are also reported and assigned.     

Radiometry in the Submillimeter Region Using the Interferometric Modulator

Radiometry in the submillimeter and far infrared regions involves problems of a type not encountered in the centimeter region which require solutions using techniques different from those used in centimeter-wavelength radiometry. The nonlinear variation of the magnitude of the black-body radiation spectral density with temperature and wavelength, the limitation of antenna beamwidth by factors connected with the size of the noncoherent detector and the antenna focal length (rather than by diffraction effects and the antenna aperture) and the heavy absorption of submillimeter radiation by atmospheric water vapor are typical of the problems normally not encountered in centimeter radiometry. The unavailability of microwave techniques (i.e., waveguides, coherent receivers, etc.) makes necessary the use of quasi-optical techniques in this wavelength region. The interferometric modulator, which has already been used in far infrared spectrometers, is proposed in this paper as the major component of a practical submillimeter radiometer. Its use as the wave-number-selection device in a radiometer is analyzed and estimates are obtained for the sensitivity of this submillimeter radiometer. It is estimated that a 0.2/spl deg/ minimum detectable temperature differential is achievable with this radiometer. Also discussed are the effects of atmospheric water vapor absorption and the sensitivity of a number of different types of radiation detectors suitable for use in the submillimeter-wavelength region.     

The Mg atomic frequency standard

Recent advances towards the realization of an absolute frequency standard in the submillimeter region are reported. The³p1-³P_{0} Delta m_{j} = 0fine structure transition in the metastable triplet of²⁴Mg has been observed in an atomic beam with both Rabi and Ramsey interrogation techniques. Experimental results and theoretical predictions are compared and discussed in view of an Mg frequency standard.     

Absorption of millimeter to submillimeter waves by atmospheric water molecules

Using the values of the rotational molecular parameters (including cencrifugal distortion terms) of the H₂ ¹⁶O molecule, which can explain 12 observed transitions below 800 GHz, all rotational energy levels with normalized Boltzmann factors larger than 5×10^?8 at 300°K are calculated. Probabilities of all possible electric dipole transitions among these states, 2277 lines, are calculated using the eigenfunctions thus obtained, and the permanent electric dipole moment of 1.8546 Debye. Assuming the single and full Lorentzian line forms, we calculated the absorption coefficient for millimeter to submillimeter region. Our result, using the single term Lorentzian line form, agrees quite well with experiment for 1 Torr of water vapor in 760 Torr air at 300°K.     

超导亚毫米波阵列振荡器的扰动模拟

本文系统地研究了超导亚毫米波阵列振荡器。首先介绍了约瑟夫森结阵列振荡器的基本原理 ,然后根据原理引出超导亚毫米波阵列振荡器的模型 ,最后 ,根据约瑟夫森原理 ,对超导亚毫米波阵列振荡器的模型进行了模拟和分析 ,仿真得出了振荡器各项参数值 ,并给出了相位锁定的条件     

Frequency multipliers for millimeter and submillimeter wavelengths

Theory and tools for analysis and design of millimeter- and submillimeter-wave multipliers are discussed. Experimental work is reviewed. The Schottky diode model at submillimeter frequencies, use of Schottky multiplier chains versus direct higher-order multipliers, and the effect of cooling on Schottky diode multipliers are discussed. Alternative diodes such as the high electron mobility varactor (HEMV), the barrier-intrinsic-n⁺ diode (BIN), the barrier-n-n⁺ diode (BNN), the quantum well diode (QWD), and the single barrier varactor (SBV) are discussed, with attention given to their potential submillimeter frequency multipliers     

Novel transmission lines for the submillimeter-wave region

A detailed presentation of the available information on the electrical properties of submillimeter-wave transmission lines is given. These lines are compared with conventional planar and nonplanar lines, such as microstrip and rectangular waveguide, in terms of performance, fabrication feasibility, and availability. Four types of novel monolithic waveguides that have shown promise for use in the submillimeter frequency range are examined. The advantages and disadvantages associated with the use of these guides are discussed     

原子发射双谱线测温常数静态标定实验研究

为了实现恶劣环境下瞬态高温的精确测量,设计了基于原子发射双谱线测温原理的光电测温器。采用高温黑体炉对光电测温器进行特定常数静态标定实验,选用CuⅠ 510.5nm和CuⅠ 521.8nm两条波长间隔小的谱线作为测温时的温标谱线,得到了测温常数A的值为0.1083,B的值为628.387。对标定后的光电测温器进行Cu燃烧温度场温度测试实验,并与计量部门标定过的M5型红外测温仪测量的标准温度进行比较。结果表明,两种方法测得温度的平均相对误差为1.3%。该研究为原子发射双谱线测温法准确测量瞬态高温提供了理论依据。     

Scanning transmission electron microscopy and its application to the study of nanoparticles and nanoparticle systems

Scanning transmission electron microscopy (STEM) techniques can provide imaging, diffraction and spectroscopic information, either simultaneously or in a serial manner, of the specimen with an atomic or a sub-nanometer spatial resolution. High-resolution STEM imaging, when combined with nanodiffraction, atomic resolution electron energy-loss spectroscopy and nanometer resolution X-ray energy dispersive spectroscopy techniques, is critical to the fundamental studies of importance to nanoscience and nanotechnology. The availability of sub-nanometer or sub-angstrom electron probes in a STEM instrument, due to the use of a field emission gun and aberration correctors, ensures the greatest capabilities for studies of sizes, shapes, defects, crystal and surface structures, and compositions and electronic states of nanometer-size regions of thin films, nanoparticles and nanoparticle systems. The various imaging, diffraction and spectroscopy modes available in a dedicated STEM or a field emission TEM/STEM instrument are reviewed and the application of these techniques to the study of nanoparticles and nanostructured catalysts is used as an example to illustrate the critical role of the various STEM techniques in nanotechnology and nanoscience research.     

Millimeter/submillimeter nonlinear spectroscopy

The techniques of coherent transient spectroscopy have been successfully applied to the microwave and optical regions of the spectrum, but lack of suitable sources has prevented convenient extension to the millimeter/submillimeter region where several strong molecular transitions occur. Analysis of the experimental requirements and theory for such experiments considering several molecules including H₂O and CH₃Cl indicates how such experiments can be performed employing recently developed oscillators with increased power.     

High‐Resolution Submillimeter Wave Spectroscopy of Hydrogen Sulphide with Heterodyne Spectrometer

A submillimeter heterodyne spectrometer using continuous wave optically pumped molecular laser as local oscillator and Schottky diode as mixer was developed at Physical Research Laboratory, Ahmedabad (India) for quantitative spectroscopy of polyatomic molecules in laboratory. The experimental details of spectrometer and its application to study of molecular line parameters are presented. In particular line strength, collision line width (self and foreign) of H₂S 5_5,0←5_4,1 transition¹(579.799 GHz) have been measured. Air molecules have been used as foreign (perturbing) molecules taking Earth’s atmosphere into consideration².