Table of contents

Characteristics of instrument science are outlined to provide an introductory background for appreciation of the literature of the subject. Various forms of literature are outlined, including discussion of the diverse terminology used. An example is used to illustrate the problems of retrieval that can arise because of the multiplicity of applicable classifications. Location of book, and of journal, material is reviewed. Appendices provide examples of standard lists of terms, terms used in searching, library catalogue numbers, relevant reference sources and related data bases.

An introductory section gives a general profile of the instrumentation and control industry in the UK, making particular mention of the increasing use of microelectronics-based systems. Subsequent sections cover in greater detail sensors, analysers, signal transmission equipment, and instrument hardware; the growing tendency for equipment to be comprised of basic hardware and adaptable software is noted.

The various semiconductor deep-level measurement techniques are often limited in their precision by thermometry. A temperature-measurement procedure is described which uses a statistical calibration of forward-biased temperature-sensing diodes to achieve a two-sigma precision of +or-8 mK. Several applications are discussed to illustrate where the improved thermometry can significantly affect the quality of the results.

Starting with a piezoelectric pick-up element for record playing a weight detector was constructed for particles with weights in the 0.1-20 mg range. The detector has a linear response, a sensitivity of at least 10 mu g and can weigh particles at a rate of at least 10 s^-1. The detector can be used for weighing and selecting, for instance, metal halide spherules for the fabrication of high-pressure discharge lamps.

This is a description of the electronic design of an arrangement which can control the columnar growth produced in electroplated amorphous CoP alloys. This method allows for total or partial interruption of the column-like growth, interleaving a series of very thin layers with greater P concentration.

A vacuum differential thermal analysis apparatus is described which can be used up to 1000 degrees C. A unique feature of the design is the facility for changing the sample with minimum disturbance to the heating and cooling systems. To test the equipment the magnetic transition in pure nickel has been investigated utilising the change in specific heat at the transition point.

A simple device that provides control for constant true strain rate compression (or tension) tests in MTS closed-loop servohydraulic testing machines is described. In the present system, it has been used at strain rates up to 20 s^-1. Intended for use in hot working studies, the device allows for single stroke, change of rate and interrupted sequential tests.

A simple metastable atom detector is described consisting of a channel electron multiplier and a heated ribbon detection surface. The use of the heated surface extends the range of detection of the electron multiplier down to metastable excitation energies of approximately 4 eV. A metastable excitation function in mercury obtained using the detector is presented. The usefulness of the device for the detection of photons and positive ions is also shown.

Large gains in the throughput of a spectrometer used for beam-foil spectroscopy may be realised without loss of spectral resolvance by matching the angle-dependent Doppler shift in the light emitted by a beam of fast atoms to the linear dispersion at the entrance slit of the spectrometer. It is shown that a condition for exact matching over the whole area of the entrance slit is that the condensing system should satisfy the optical sine relation.

The changes in groove form across several diffraction gratings due to wear of the diamond ruling tools have been investigated. The measuring instrument used was a Talystep which traces the groove profiles directly. All the gratings were ruled in aluminium films. The groove profiles were found to change continuously with a general tendency for the blaze wavelength to shift to higher values as the ruling progressed. There is also a corresponding drop in the peak efficiency due to loss of form. No evidence was found to support the suggestion of an induction period in which the diamond shows no apparent wear.

A thermistor using a sputtered SiC film has been developed as a temperature-sensing device which is able to detect temperatures accurately over the wide range of 30-300 degrees C. The thermistor has a unique characteristic in that the B constant increases linearly with an increase of temperature. The typical values of the B constant increase from 1950K at 50 degrees C to 3080K at 250 degrees C. From this unique characteristic, the temperature dependence of resistance was calculated with high accuracy by an experimental equation. The thermistor consists of a thermistor element and a package. The thermistor element comprises the SiC film temperature sensor. The package comprises a small glass tube in which the thermistor element is sealed hermetically. The characteristics of the thermistor are very stable for long periods under various test conditions.

A spectrometer is described which consists of retarding field grids and a post-monochromator, and which is constructed to detect electrons emitted into the backward hemisphere in ion-atom collisions. The construction is such that the impinging ion beam passes through the spectrometer before colliding with the target foil. The experimental line width (FWHM) for monochromatic electrons is 6-8 eV in the energy range 150-800 eV. An account of the performance of the spectrometer in ion-atom collision experiments is given.

A low-temperature parallel-plate capacitance/conductance cell is described which permits sample loading at temperatures far from ambient and which compensates for sample irregularity and differential thermal expansion/contraction. The cell performs equally well for liquids and for well formed solid samples at frequencies up to 10 MHz with an accuracy approaching 1%. Typical performance to 2K is illustrated using data pertaining to the double clathrate hydrate of hydrogen sulphide and 1,2-dichloroethane.

Using simple reflection and total reflection methods at the same time, it is possible to cover the band 2 MHz-8 GHz by reflectometry in the time domain. The signal analysis and treatment are automatically done within 20 min through a calculator connected with the measuring device.

Proposes measurement of dynamic hysteresis loops of magnetic samples by the use of a high speed digital voltmeter. The advantage of this method is that a simple and accurate automatic measuring device may be built up, where all data are immediately displayed by computer-compatible techniques.

The effect of the inductance in an LC inversion circuit on the stable operating voltage range and output of a TEA CO₂ laser has been investigated. The inductance value determines the laser electric/optical energy conversion efficiency and output peak power. In addition, the rate of dissociation of CO₂ in the laser discharges was found to depend on the inductance. The observations are shown to be consistent with a change in the value of the ratio of electric field to neutral gas number density, E/N, at which energy is deposited into the discharge.

Theoretical and practical problems arising in the application of microwave interferometry to density measurements on transient plasmas are discussed. The conditions for unambiguous measurements in a density range as wide as possible are analysed. It is shown that the initial zero adjustment of the interferometer bridge recommended in most text books is the worst possible choice of initial conditions when the aim is high initial sensitivity at low densities. The analytical expressions needed for unambiguous evaluation of any phase shift from a few degrees to several times pi (counting fringes) are derived. It is pointed out that, in cases of strong intensity variations of the microwave beam transmitted through the plasma, accurate evaluation of the phase shift is possible only by using the exact analytical expressions instead of approximate formulae. The practical design of the interferometer circuit and its inherent error sources due to reflections and non-ideal component properties are discussed. The results are applied to an interferometer operating at 80 GHz used on a pulsed plasma experiment. Examples of measurements are given and the evaluation of the phase shift and plasma density is discussed in detail. The minimum measurable phase shift is 2 degrees and the range of linear densities that have been measured is integral n_edx=3*10¹⁵-3*10¹⁸ m^-2, with L= integral dx//0.1 m approximately=0.1 m.

A digital approach to spectral analysis is described in connection with laser Doppler anemometry using a multiplexed scanning Fabry-Perot spectrometer.

Describes a new CW-NMR dispersion spectrometer based on the detection of the frequency shift of a cryogenic tunnel diode oscillator, in which the inductance of the coil is influenced by the magnetic resonance phenomenon. Besides the design, the details of the construction and the operation of the oscillator, an outline of the performances and the major advantages and disadvantages of this spectrometer are given. The performances are compared with those of conventional NMR absorption (and dispersion) spectrometers.

Describes a simple optical technique which can improve resolution in the photographic recording of small areas of interest separated by large areas containing no information. The technique was developed for dynamic compression tests of materials, in which the record of strain is obtained from a high-speed camera recording the small outward displacement of opposite sides of a cylindrical specimen. An optical device consisting of inclined transparent plates shifts parts of the image, so that the unwanted central region is deleted from the photographic frame. The edge displacements are recorded at a higher magnification, and the improvement in accuracy of the strain records can be up to a factor of about 10. An extension of the technique is also described which optically enhances radial displacements and deviations from circular symmetry in an image.

The May spinning-top aerosol generator has been developed to produce high-quality monodisperse solid aerosols. Correct adjustment of the liquid feed needle with respect to the rotor is essential to produce such aerosols. A semi-remote needle support system has therefore been developed to achieve precise movement and control of the needle. This device is inexpensive, easy to maintain, and can be attached to the existing aerosol generator. Results demonstrating the capabilities of the modified equipment are reported.

The physical principles underlying the use of gamma-ray scattering to detect composition variations in bulk alloy samples are described and the sensitivity of the method, which is an alternative to conventional transmission radiography, is evaluated for titanium alloys. The elastic (Rayleigh) and inelastic (Compton) scattered beams are recorded separately and their intensities used to monitor composition changes collectively and individually. The sensitivity of the method is illustrated by measurements on titanium alloys containing aluminium and zirconium.

The medium density plasma column (n approximately=10²² m^-3) close to the exit of the cathode of a hollow cathode arc is highly ionised, with ion and electron temperatures T_i approximately=0.5-1.5 eV and T_e approximately=3 eV, respectively. By sampling this plasma with an orifice in the end anode (at a floating potential) a high intensity beam with a broad velocity distribution is obtained for the noble gas atoms Ne, Ar and Kr, both in the ground state and in metastable states n*. Typical centre-line intensities for argon are I(0)=2*10¹⁸ s^-1 sr^-1, T=2*10⁴K and I(0)_n*=2*10¹⁴ s^-1 sr^-1, T_n*=3*10⁴K. These values are in good agreement with model calculations of the process of molecular beam sampling, which are discussed in this paper. The source is of a simple design and easy to operate. The life time of the tungsten (or tantalum) hollow cathode is typically 40 h for argon and krypton. The shortest life time is for neon with a tungsten cathode, due to the high operating temperature T approximately=3000K of the cathode tip.

A new electrostatic lens capable of correcting third-order aperture aberration is proposed. The new lens is called a self-aligned quadrupole correction lens and consists of an electrostatic quadrupole and an aperture electrode. An octopole field component is automatically created within the quadrupole field by excitation of the aperture electrode. The potential distributions of this lens are calculated by successive over-relaxation techniques involving the numerical solution of Laplace's equation in three dimensions. Correction properties for all the aperture aberration coefficients are obtained by using the potential distributions. The aperture aberrations have been accurately measured by means of the shadow-image technique, and compared with those calculated using the above potential distributions. It was confirmed experimentally that the aberration in the convergent plane can be cancelled completely by the new correction method.

An optical high-pressure cell is described which allows one to measure absolute values of small absorption coefficients at liquid-nitrogen temperatures, in a wide range of wavelengths at pressures up to 1.2 GPa (12 kbar). This technique involves a sample rotation system which operates at high-pressure low-temperature conditions.