New technologies make it possible to cast, polish, and support large light-weight mirrors with f/ratios faster than f/2.0. These new technologies have dramatically lowered the cost of construction of ground-based telescopes, and accordingly several telescopes with apertures of 8-10 meters are now under construction. Some of these telescopes are being optimized for fiber spectroscopy of one to a few hundred objects during a single exposure. The required design characteristics and the properties of the best commercial fibers currently available are discussed. Applications of fiber spectroscopy to such problems as the mapping of distant galaxies, the search for extra-solar-system planets, and the measurement of stellar pulsations are briefly described.

The basic idea involved in a universal birefringent filter (UBF) in which light in a single state of polarization is forced to interfere with itself is reviewed along with the basic properties of the filter. The Fabry-Perot interferometer (FPI) representing an optical resonant cavity is described as well as an FWHM filter utilizing both UBF and FPI. It is pointed out that such a device can achieve a resolving power of about 300,000 and can be tuned continuously between 4200 to 7000 A. It is suggested that by using UBF in conjunction with FPI, it is possible to record monochromatic images of the solar atmosphere up to 400 times the width of the telescope diffraction pattern.

The term `adaptive imaging spectrometer' is taken to imply that the instrumental characteristics can be adapted via purely electronic means to provide significantly altered observational capabilities. The paper demonstrates selected characteristics of the acoustooptic tunable filter (AOTF) that include simultaneous acquisition of orthogonally polarized spectral images at high spatial resolution of transmittance (greater than 75 percent), polarization contrast between the orthogonally polarized images of over 10,000, permitting accurate measurement of the polarization parameters of incident light, operation of the AOTF as a no-moving parts shutter with a contrast of about 10000 on a submillisecond time scale and electronic control of the pass band.

Advances in two dimensional detectors have created a need for a spectrograph that can produce high fidelity images. Aberrations that detract from image quality in conventional spectrographs are discussed. Ray trace and experimental results obtained for a unique spectrograph designed for use with array detectors, i.e., designed to produce high fidelity images, are presented. The spectrograph employs toroidal mirrors to achieve stigmatic imaging in a flat focal field.

The paper presents a spectrometer combining echelles with imaging detectors and optimizing the echelle design to match the behavior of the detector, to be used for simultaneous high-resolution multiwavelength observations of a variety of discharges. The instrument utilizes a dual Czerny-Turner mount, with compensation of astigmatism generated in the first spectrometer by arranging the second spectrometer in a plane orthogonal to the first. Software for displaying spectra in false color, extraction of orders from echellograms, and wavelength calibration is outlined. Application of the spectrometer to the study of three plasma systems is described.

Resonance ionization mass spectrometry (RIMS) is an analytical tool discovered in the 1970's, developed primarily in the 1980's, and one which will undoubtedly see continued and expanding use through the 1990's. This technique combines laser ionization with mass spectrometric sorting and detection to yield analyses of unparalleled sensitivity and selectivity. We discuss the application of RIMS to the analysis of conventional analytical samples, as well as the combination of RIMS with laser or particle beam sputtering for the analysis of solids and surfaces with minimal sample preparation.

We present the use of coherent anti-Stokes Raman scattering (CARS) in conjunctiOn with a two-stage light-gas gun to obtain vibrational spectra of shock-compressed liquid N2, 02, CO. and their mixtures. The experimental spectra are compared to spectra calculated using a semiclassical model for CARS intensities to obtain vibrational frequencies, peak Raman susceptibilities, and linewidths. The derived spectroscopic parameters suggest thermal equilibrium of the vibrational populations is established in less than a few nanoseconds after shock passage. Vibrational temperatures obtained are compared to those derived from equation-of-state calculations. Shifts in the vibrational frequencies reflect the influence of increased density and temperature on the intramolecular motion.

No abstract available.

Laser-induced breakdown spectroscopy (LIBS) has been used for a variety of applications, usually those requiring remote or in situ spectrochemical analysis. Several beryllium monitoring instruments based on LIBS have been built. The progress and implementation of this technique will be reviewed.

The abundances of rare earth elements in metal-poor stars of the Galactic halo are reexamined in light of new publications oflaboratory transition probabilities of these elements. The species Nd H, Sm II, Gd II, and Ce II are considered in some detail, and it is suggested that the abundances for Sm and Nd now are fairly reliable, while more work should be clone on Gd and especially Ce. The revised abundances are compared to predictions of neutron capture theories, and it is argued that the Nd/Sm abundance ratio now is in closer agreement with r-process nucleosynthesis than seen in previous papers. Finally, suggestions are made for future work for transition probabilities, for stellar observations, and for nucleosynthesis theory.

The inductively coupled plasma is widely used as a radiation source in analytical emission spectrometry. Because of the richness of the spectra and the line broadening, the role of the resolving power of the dispersive system is very important. Monochromators allow a flexibility in line selection and can be optimized to obtain the best experimental resolution. Considering the range of the physical line widths of analytes observed in the plasma, specifications can be given for the instrumental broadening of the monochromator. Parameters influencing the instrumental broadening will be described with an emphasis on the resultant spectral slit width. Consequences on the optimization of the signal to background ratio will be discussed.

The inductively coupled plasma is widely used as a radiation source in analytical emission spectrometry. Because of the richness of the spectra and the line broadening, the role of the resolving power of the dispersive system is very important. Monochromators allow a flexibility in line selection and can be optimized to obtain the best experimental resolution. Considering the range of the physical line widths of analytes observed in the plasma, specifications can be given for the instrumental broadening of the monochromator. Parameters influencing the instrumental broadening will be described with an emphasis on the resultant spectral slit width. Consequences on the optimization of the signal to background ratio will be discussed.

Fourier transform spectrometers are considered, and emphasis is placed on resolution and the speed of data acquisition. Detector linearity requirements are discussed as well as trading the multiplex advantage for the throughput advantage. Radiometric accuracy is considered, and focus is placed on instrument design and operational parameter optimization. Issues of calibration are presented, and it is noted that using black bodies for calibration can saturate the detector with long-wavelength radiation, before sufficient signal-to-noise ratio for the short-wavelength radiation is reached. It is suggested to look for secondary calibration sources and to refrain from calibrating a narrow-band emission spectrum with a black-body radiator.

An infrared spectroscopy instrument for infrared remote sensing from the Cassini orbiter is being breadboarded in the laboratory. The Composite Infrared Spectrometer (CIRS) consists of a pair of Fourier Transform Spectrometers (FTS) which together cover the range from 10 - 1400/cm with a spectral resolution up to 0.5/cm. The far-infrared FTS is a polarizing interferometer covering the 10 - 300/cm range. The mid-infrared FTS is a conventional Michelson FTS covering 200 - 1400/cm in three spectral channels. CIRS will retrieve information on the atmospheres of Titan and Saturn with good vertical resolution, from deep in their tropospheres to high in their stratospheres, and into the upper few centimeters of the regoliths of icy objects. The science objectives and design of CIRS are discussed.

Two well established methods for performing optical spectrometry are dispersive spectrometry (DS) and Fourier transform spectrometry (FTS). A third alternative is Hadamard transform spectrometry (HTS), which is a marriage of dispersive and multip1exin techniques and possesses some of the desirable features of both DS and FTS . The general features o[3the Hadamard transform (HT) spectrometer are3dscribed in the literature as are the specifics of our HT spectrometer . The theory and practical examples of the most efcient way to carry out a multiplexing technique such as HTS are available '

Recent advances in the study of velocity fields in stellar atmospheres made possible by the development of solid-state diode arrays are reviewed. The Fourier transform is considered as a tool for exploring broadening of lines by rotation and turbulent velocities, and a few examples of broadened profiles are presented. It is noted that in matching models with observations, velocity shifts from each of the expected velocities should be computed point by point across a model stellar disk and coadded. It is pointed out that rotation tends to amplify asymmetries in profiles produced by granulation cells on star surfaces. Attention is focused on processes in hot stars arising from nonradial pulsations and the acceleration of blobs embedded in the outward flowing escape of the radiative wind.

New techniques for the high precision measurement of variations in stellar radial velocities now allow a precision of better than 5 m/s to be obtained in routine telescopic observations. Some of the factors limiting velocity precision and how they can be overcome are discussed. Also presented are applications of these new techniques to the problems of detection of planetary systems around other stars and the use of stellar oscillations to determine interior properties of the stars.

Production of the ionic spectrum of metal atoms forming the cathode of a hollow cathode glow discharge is affected by gas phase charge transfer reactions. This is observed in a copper hollow cathode lamp in separate experiments for helium, neon, argon, krypton, and xenon fill gases. The copper ionic line -atomic line emission intensity ratio is increased with fill gases which have metastable or ionization energies greater than the excitation energy of the copper ionic line. Potential application of ionic line emission sources to atomic (ion) fluorescence in inductively coupled plasmas is presented.

The coupling of laser ablative sampling with inductively coupled plasma-mass spectrometry (ICP-MS) has resulted in a very sensitive technique for rapid elemental analysis of virtually any solid material. ICP-MS is characterized by simple mass spectra, excellent detection limits, and the availability of isotope information. In laser sampling ICP-MS, the output of a pulsed Nd:YAG laser is focused onto the surface of a solid sample, and the resulting vaporized material is transported to the ICP-MS, which serves as the detector. Sample materials that have been investigated include ceramics, archaeological artifacts, and geological powders. Results for these and other "difficult" samples will be presented and discussed.

Direct analysis of solid materials without sample digestion are requirement in analytical plasma emission spectrometry. Laser ablation permits the production of fine particles to be atomized, excited and ionized in a secondary source such as an inductively coupled plasma. Laser characteristics such as the pulse duration, the beam shape and the wavelength seem to play a significant role in the shape of the crater and the amount of ablated material. A Nd:YAG laser at 1064, 532 and 355 nm has been compared with a XeCl laser at 308 nm. Using the various lasers, crater shapes are described and amounts of ablated material are compared.

The system described in this paper is an optoelectronic module for a medical diagnostic instrument used to evaluate 20 biochemical reactions at 35wavelengths using photodiode arrays in the charge storage mode of operation. This paper examines the optical and electrical multiplexing of the signals and their eventual digital conversion. The charge coupled mode of optical to electrical conversion is discussed in detail. Since the charge coupled amplifier integrates the photon to electrical conversion over time, it provides maximum signal for low level light while niithmizing component cost.

A method for performing bi-dimensional solar spectroscopy by utilizing a narrow passband filter (NPF) is presented. The basic principles of the NPF technique are outlined along with a typical instrument setup. An observation program, collection of CCD images, and their correction are described. Advantages of the method, including the immediate use of spectral images for morphological studies, the recoverability of the line profile for every point of FOV, and the ability to follow the temporal variations of physical parameters by means of the cyclical sampling of spectral lines are analyzed as well as constraints due to the sequential acquisition of the monochromatic images.

In the 1980's many exciting advances in the field of soft x-ray lasers took place. A novel experimental set-up was developed at Princeton to improve the performance and extend the wavelength range of existing soft x-ray lasers. In th1s paper a new target manipulation system capable of remotely aligning multiple targets in a vacuum chamber within a magnetic field is described Alignment to the magnetic field orientation, incident pump laser and the two axial diagnostics: a high resolution spectrometer equipped with a multichannel array and a time resolved imaging spectrometer is presented. We include a brief explanation of the Macintosh- Camac based data acquisition system. In addition we discuss the possibifity to increase in the near future the brightness of the x-ray laser beam by several orders of magnitude by developing a cavity with multilayer mirrors.

A compact sample cell assembly for (multicomponent) fluids to be used in light scattering experiments of controlled temperatures and pressures has been designed and built. The sample cell itself is a quartz capillary tube of length 16 mm and of inner and outer diameters 4 mm and 8 mm respectively. It is mechanically supported by a brass block structure sealed to the tube by two 0-rings. The present version has been multiply tested in the pressure over 700 Bars. The temperature can be controlled from room temperature up to 150°C with temperature stability 0.01°C.

A photodiode-array spectrometry characterized by fast data acquisition, simultaneous readings at multiple wavelengths, reproducibility, a wide dynamic range, and enhanced accuracy due to a low instrument drift is considered for on-line real-time monitoring of the trace levels of metal ions in water solutions for environmental, power plant, and space applications. An experimental application for NASA's Controlled Ecological Life Support System is outlined along with nuclear-plant monitoring applications. Steps involved in the developing of an algorithm for on-line multicomponent analyses in absorption spectrometry are presented, and a photodiode-array spectrometer used in the described experimental investigations is detailed.

Spatial heterodyne spectroscopy (SHS) employing a two-beam dispersive interferometer producing a Fizeau fringe pattern having wavelength-dependent spatial frequencies is presented. The pattern is recorded on an imaging detector and Fourier transformed to recover the input stream. It is pointed out that spectrometers operating on the SHS principle can achieve the theoretical resolution limit of the gratings without scanning, retaining at the same time the large angular input tolerance and multiplexing properties of conventional scanning Fourier-transform spectrometers. Additionally, broad spectral coverages can be achieved, and field widening can be accomplished without moving parts.

We have recently developed a miniature electronically tunable, servo controlled Fabry-Perot filter for use in fiber optic sensors, spectroscopy, data and telecommunications, and laser tuning. The servo control system utilises capacitance micrometry and piezo technology to maintain stable cavity mirror separations with a noise of