Fourier transform pulsed-gradient spin-echo studies of molecular diffusion

http://antonirogalski.com/wp-content/uploads/2011/12/Infrared-detectors-Status-and-trends.pdf

Infrared detectors: status and trends

This review describes bolometric detectors for infrared and millimeter waves. The introduction sketches the history of modern bolometers, indicates how they fit into the more general class of thermal detectors, and describes the types of applications for which they are the optimum solution. Section I is a tutorial introduction to the elementary theories of bolometer response, of thermal radiation, and of bolometer noise. Important results are derived from the laws of thermal physics in the simplest possible way. The more rigorous theories of bolometer response and noise that are required for quantitative understanding and optimization are then summarized. This material is intended to provide the background required by workers who wish to choose the appropriate bolometer technology for a given measurement, or to evaluate a novel technology. Section II, then describes the various components of an efficient bolometer and gives details of the fabrication and performance of modern bolometers. This discussion f...

/pdf/bolometers-for-infrared-and-millimeter-waves-3ap6cv7sab.pdf

Bolometers for infrared and millimeter waves

A full mathematical framework for the analysis and production of localized magnetic field profiles is presented. Of primary use in the production of highly homogeneous fields for nuclear magnetic resonance studies, the paper details the analysis of fields in terms of spherical harmonics, describes how field plotting in the appropriate manner may be used to obtain a direct measure of which harmonics are present, and shows how to combine basic "building blocks" to produce the various lower-order zonal and tesseral harmonics. "Building blocks" described include coils, arcs, and sinusoids of current as well as rings and arcs of steel. The use of shaped magnets is also briefly mentioned. Attention is drawn to the presence, in high-order designs, of possibly dominant lower orders of harmonics created by errors in fabrication. The goal of the paper is to present a design philosophy, backed by the appropriate mathematics, which is applicable to the variety of situations encountered in magnet design. Practical examples of correcting coils and "shims" are also given.

Magnet field profiling: analysis and correcting coil design.

This paper overviews the history of infrared detector materials starting with Herschel’s experiment with thermometer on February 11th, 1800. Infrared detectors are in general used to detect, image, and measure patterns of the thermal heat radiation which all objects emit. At the beginning, their development was connected with thermal detectors, such as thermocouples and bolometers, which are still used today and which are generally sensitive to all infrared wavelengths and operate at room temperature. The second kind of detectors, called the photon detectors, was mainly developed during the 20th Century to improve sensitivity and response time. These detectors have been extensively developed since the 1940’s. Lead sulphide (PbS) was the first practical IR detector with sensitivity to infrared wavelengths up to ∼3 μm. After World War II infrared detector technology development was and continues to be primarily driven by military applications. Discovery of variable band gap HgCdTe ternary alloy by Lawson and co-workers in 1959 opened a new area in IR detector technology and has provided an unprecedented degree of freedom in infrared detector design. Many of these advances were transferred to IR astronomy from Departments of Defence research. Later on civilian applications of infrared technology are frequently called “dual-use technology applications.” One should point out the growing utilisation of IR technologies in the civilian sphere based on the use of new materials and technologies, as well as the noticeable price decrease in these high cost technologies. In the last four decades different types of detectors are combined with electronic readouts to make detector focal plane arrays (FPAs). Development in FPA technology has revolutionized infrared imaging. Progress in integrated circuit design and fabrication techniques has resulted in continued rapid growth in the size and performance of these solid state arrays.

https://web.xidian.edu.cn/bjwang/files/20140924_180458.pdf

History of infrared detectors

Work on infra‐red detectors, and particularly on infra‐red pneumatic detectors, pursued in the Signal Corps Engineering Laboratories from 1932 to date, has been briefly reviewed. A typical pneumatic infra‐red detector and laboratory techniques are described.

A Pneumatic Infra‐Red Detector

A brief mathematical review of the basic factors involved in infra‐red detection is presented, with emphasis on the concepts of equivalent circuits and efficiency. A few theoretical aspects of the pneumatic detector are discussed.

Theoretical consideration in heat and infra-red detection, with particular reference to the pneumatic detector.

The coils described in this paper are assembled in two relatively thin flat stacks which are placed on each pole piece of a nuclear spin resonance magnet. One coil of each coil pair is in each of the two stacks, and each coil pair is so designed that the current circulating in it produces, in the airgap center, a correcting magnetic field describable by one of a set of spherical harmonics. The orthogonal properties of the spherical harmonics render possible substantially independent adjustments of the currents in the several coil pairs, when some spin resonance parameter such as line width is utilized to determine that individual optima are reached.Experimental coil stacks with 13 coil pairs, for the second, third, and zonal fourth harmonics, have been constructed, and preliminary results obtained by Rex Richards (Oxford) indicate that when a 4‐mm spin sample is used, this method can serve to reduce field inhomogeneities to less than 1 part in 108 with few sets of 13 current adjustments.

Field Homogenizing Coils for Nuclear Spin Resonance Instrumentation

Following an introductory sketch of the application of the pneumatic infra‐red detector to spectrometry, the absolute sensitivity of a pneumatic detector is calculated for the case of an infinitely extended flat heat cell. The calculated r.m.s.e.n.i. is seen to be in good agreement with the experimental results.

The Theoretical and Practical Sensitivity of the Pneumatic Infra‐Red Detector

A pneumatic heat detector is described in which radiant energy is dissipated in a black absorber which is located in the center of a gas cell. The resulting heating and expansion of the gas serves to distort a collodion film located a few thousands of an inch from a nearby parallel glass window. The distortion of the film is detected by observing a shift in a system of interference fringes formed by light reflected from the film and the adjacent glass surface. The principle lends itself readily to the design of systems comprising a multiplicity of heat cells and associated detecting films. A system utilizing 61 cells is described.

Marcel J. E. Golay

Papers

A Pneumatic Infra‐Red Detector

Theoretical consideration in heat and infra-red detection, with particular reference to the pneumatic detector.

Field Homogenizing Coils for Nuclear Spin Resonance Instrumentation

The Theoretical and Practical Sensitivity of the Pneumatic Infra‐Red Detector

Pneumatic heat detector.