UV curing, the process of photoinitiated conversion of polymeric materials from a liquid to a solid, is rapidly becoming a popular alternative to conventional drying. The number and variety of applications for UV curable inks, coatings, and adhesives continue to expand at a rapid pace, and pose new design challenges to increase cure efficiency, speed, and the physical properties of the cured polymer film. The latest developments in microwave powered lamps for industrial processing are presented. Among these are: (1) the selection and control of the lamp emission spectra to match the optical properties of the film and its photoinitiator, (2) sustained high power lamp operation at 6 kilowatts, and (3) the use of absorptive dichroic reflectors to manage the relative components of UV and infrared energy in the highly focused radiation delivered to surfaces being processed. The ability of a high power UV lamp system to provide a nearly constant output over thousands of hours of operation is, in large measure, a function of its design, construction, and materials. Five-thousand-hour lamps are now a practical reality.

As the ultraviolet processing industry continues to grow, more and more applications involving heat sensitive substrates are evolving. Unfortunately, ultraviolet lamps also emit a significant portion of their output in the visible and infrared regions of the spectrum; if not reduced, the absorption of this energy by the product can preclude the processing of some substrates due to overheating. This fact, together with the continuing development of more powerful ultraviolet lamps, creates the need for methods to reduce the unwanted heating of the substrate during or immediately after processing. This is crucial because overheated substrates not only can affect the final properties of the material, but can also cause out of register printing due to web elongation or sheet expansion. Cooling of substrates during or after ultraviolet processing can be accomplished by several methods. Among these are: (1) UV processing over a cooled rotating drum; (2) Conductive cooling through cold nip rolls or cooled drums after UV processing; (3) Convective cooling with cool air after processing. Unfortunately, in many applications, these methods are not practical because of space limitations, complexity of the process (e.g. sheet-fed printing), or substrate speed. This paper deals with the available means to reduce much of the unwanted energy emitted from the ultraviolet lamp rather than with the means to remove excess heat after its deposition on the product. It discusses the advantages and penalties associated with these methods and in which industries they are being successfully applied.

Diamond has long been recognized as a promising material for fabricating robust, solar-blind radiation detectors. Its electrical as well as mechanical and chemical properties suggest that detectors made from diamond will not be limited by the dark current and response instabilities that plague silicon devices. In this work, we present initial results from our program to fabricate a two dimensional imager using synthetic diamond. We have observed the desired low dark current and VUV spectral response properties in metal-semiconductor-metal (MSM) detectors made on intrinsic type-IIa diamond. Selective, near-UV response has been produced in diamond diodes. Integrating photoresponse was observed in MIS capacitors fabricated on type IIb (p-type) diamond. Subsequent modelling of the MIS photoresponse supports the conclusion that electrons are stored at the diamond-insulator interface which makes it feasible to consider a diamond CCD. We discuss relevant processing steps and a plan to make a thin, back-illuminated CCD suitable for VUV and near-UV imaging applications.

Silicon photodiodes which operate satisfactorily in the extreme ultraviolet (EUV) have been commercially available for the past few years. These photodiodes also inherently respond to radiation extending from the x-ray region to the near infrared, a property which is undesirable in many EUV applications. The addition of a thin film of a suitable filtering material to the surface of such a photodiode can accomplish the restriction of the sensitivity of the silicon to a much narrower band, or bands, in the EUV. This results in a rugged, yet sensitive photometer for applications in which dominant out-of-band radiation is present. Applications include plasma diagnostics, solar physics, x-ray lithography, x-ray microscopy, and materials science. Previous attempts to produce such devices have resulted in degraded shunt resistance with a corresponding increase in background noise. Prototype detectors have now been fabricated using directly deposited films of aluminum, aluminum/carbon, aluminum/carbon/scandium, silver, tin, and titanium, without degradation of the noise characteristics of the uncoated photodiodes. Measured and theoretical sensitivity data are presented, as well as a discussion of relatively simple methods to reduce the x-ray response of such filtered detectors.

Epitaxial growth of III-V semiconductor materials is probed in a molecular beam epitaxy reactor by single photon ionization of the gaseous fluxes using vacuum ultraviolet (VUV) laser radiation. The ninth harmonic of the Nd:YAG laser is produced by frequency tripling the output to 355 nm and then to 118 nm in a Xe/Ar mixture. Together with a time-of-flight mass spectrometer, this radiation is used to selectively probe the gaseous fluxes of Ga, As, As₂, and As₄ during molecular beam epitaxy of III-V materials. The essential aspects of the method and details of calibration procedures to obtain relative fluxes are described. Cracking of the arsenic species does not occur in the laser/mass spectrometer, making relative species concentration measurements very reliable. Rapid data acquisition provides real time measurements of the fluxes of incident and scattered or desorbed materials during growth. Several basic examples are considered, including the thermal cracking of As₄ on silicon and the desorption of arsenic and gallium species from GaAs during epitaxial growth. Recent work to correlate the flux determinations with reflection high energy electron diffraction (RHEED) oscillations during GaAs epitaxial growth is discussed.

Boron nitride phosphide (BN_xP_1-x) films were grown on single crystal GaAs, using chemical vapor deposition. The films were smooth, well adhered to the substrate and exhibited resistivities on the order of 10¹¹ ohm-cm. Photoconductive detectors fabricated from these films showed quantum efficiencies of 33% and 40% at 254 nm and 365 nm respectively, with a drop of an order of magnitude at wavelengths greater than 400 nm. These measurements demonstrate the potential of BN_xP_1-x as a material for visible- blind UV detectors.

Fourier transform spectroscopy (FTS) combines the advantages of high resolution (sufficient to resolve Doppler line widths) with large optical throughput and an accurately linear wavenumber scale. The resolving power of about a million required for studies of atoms or molecules at 300 K has previously been achieved with the Imperial College FT spectrometer for VUV wavelengths down to 178 nm, the cut-off of the silica beamsplitter. This beamsplitter has a unique configuration, designed to ensure alignment at short wavelengths. We have now extended the wavelength range further into the VUV by replacing it with a similar beamsplitter made from a single MgF₂ crystal. The performance of the spectrometer with the new beamsplitter has been evaluated, and emission spectra from hollow cathode lamps have been recorded down to about 150 nm with a resolution of 0.08 cm^-1, representing a resolving power of 850,000.

An imaging Fabry-Perot interferometer combined with a CCD detector can provide extremely high sensitivity for the detection of diffuse atmospheric spectral emission features. We present a description of the theory and operation of a modern servo-stabilized Fabry-Perot etalon, derive the limiting sensitivity for typical optical configurations, and present astronomical observations of faint, diffuse emission line sources as examples of the technique. We show that sources with intensity as faint as 10^-2 Rayleigh can be detected with a few hours of integration.

A possibility is considered of obtaining photoelectron spectra of solid state samples near the Fermi edge at an energy resolution down to 1 meV and moderate spectra accumulation times with the help of a time-of-flight analyzer combined with a specially designed UV laser source. Limitations of count rate for such a device and their influence on the energy resolution are considered. The requirements to the laser sources including their wavelengths, pulse duration, repetition rate and pulse energies are discussed. Several possibilities are considered to build the necessary laser source, basing on excimer laser and nonlinear-optically converted neodymium-doped, argon and dye lasers. The construction of required source is shown to be quite feasible. KEYWORDS: laser, photoemission, time-of-flight electron energy analyzer, superconductivity.

Microchannel plate (MCP) photomultiplier tubes (PMTs) have been used extensively for many years. Early single anode and multianode MCP/PMTs were described by Boutot & Pietri and Catchpole & Johnson, respectively. Some recent advances that are being made are described in this paper. Compact and rugged PMTs are becoming increasingly important as electro- optical sensors for land and airborne tactical military systems. They have the ability to detect individual photons over a broad spectral range, from the UV to the near-IR regions. A multianode MCP/PMT has been developed with a 10 X 10 array of parallel signal readout PMT channels built into a single vacuum envelope. The design of a new type of multilayer ceramic body with an integral anode feedthrough assembly is described. This new PMT design achieves greater than 15% detection efficiency at 254 nm input irradiation with more than six decades of dynamic range.

The special sensor ultraviolet limb imager (SSULI) is an ultraviolet limb imaging spectrograph under development by the Naval Research Laboratory for the Defense Meteorological Satellite Program (DMSP). The instrument will measure limb intensity profiles of the earth's airglow in the extreme and far ultraviolet (800 to 1700 angstrom) with 12 - 15 angstrom resolution. The SSULI uses a rotating mirror to scan the instrument field-of-view through 17 degrees to view from 750 km to 50 km tangent altitude. SSULI measurements will be used to infer altitude profiles of ion and electron density and neutral density. A total of five SSULI instruments will be flown on the DMSP Block 5D3 satellites the first of which is scheduled for launch in the latter half of the decade. An additional copy will be flown aboard the Space Test Program (STP) ARGOS satellite in late 1995. Every optical component in SSULI was independently measured followed by system level instrument calibrations. The first SSULI instrument is complete and the preliminary calibration results validate the design expectations. Assembly and calibration of the remaining instruments is underway. This paper presents the preliminary calibration results from SSULI #1 and component test results of the wedge and strip anode microchannel plate detector, grating, collimator and scan mirror. In addition, calibration techniques used to determine detector quantum efficiency, counting linearity, resolution, wavelength and absolute calibration are discussed. A brief discussion of the log term calibration plans for the SSULI instruments including periodic calibration checks during storage, in-flight calibrations using stars and ground truth measurements is presented.

A facility for calibrating far ultraviolet and extreme ultraviolet instruments has recently been completed at the Naval Research Laboratory. Our vacuum calibration vessel is 2-m in length, 1.67-m in diameter, and can accommodate optical test benches up to 1.2-m wide by 1.5-m in length. A kinematically positioned frame with four axis precision pointing capability of 10 microns for linear translation and .01 degrees for rotation is presently used during vacuum optical calibration of SSULI. The chamber was fabricated from 304 stainless steel and polished internally to reduce surface outgassing. A dust-free environment is maintained at the rear of the vacuum chamber by enclosing the 2-m hinged vacuum access door in an 8 ft. by 8 ft. class 100 clean room. Every effort was made to obtain an oil-free environment within the vacuum vessel. Outgassing products are continually monitored with a 1 - 200 amu residual gas analyzer. An oil-free claw and vane pump evacuates the chamber to 10^-2 torr through 4 in. diameter stainless steel roughing lines. High vacuum is achieved and maintained with a magnetically levitated 480 l/s turbo pump and a 3000 l/s He⁴ cryopump. Either of two vacuum monochrometers, a 1-m f/10.4 or a 0.2-m f/4.5 are coaxially aligned with the optical axis of the chamber and are used to select single UV atomic resonance lines from a windowless capillary or penning discharge UV light source. A calibrated channeltron detector is coaxially mounted with the SSULI detector during calibration. All vacuum valves, the cooling system for the cryopump compressor, and the roughing pump are controlled through optical fibers which are interfaced to a computer through a VME board. Optical fibers were chosen to ensure that complete electrical isolation is maintained between the computer and the vacuum system valves-solenoids and relays.

The primary objective of this effort is the development of instrumentation and techniques for determining the species, concentrations and lifetimes of atmospheric pollutants that may be generated by U.S. Air Force operations. The instrumentation being developed covers the spectral range of 200 nm to 900 nm, namely, the middle ultraviolet, the near ultraviolet, the visible and a portion of the near infrared. It has the capability of scanning throughout this range to look for unknown pollutants and also to look in detail at one or more suspected pollutants. The advantages of looking in this wavelength range, as well as some limitations, are discussed. Among the characteristics of the instrumentation that are described are the focal length and aperture ratio of the spectrometer, the gratings used, the spectral resolution and spectral dispersion of the spectrometer, the CCD detector, the digitization of the video signal, and the computer with the software needed for controlling the instrumentation and for recording and analyzing the data. Special attention is placed on the sensitivity of the instrumentation which is expected to be in the parts per trillion range for those molecules that have a substantial absorption cross section.

This paper is a review of selected previously published articles from 1992, 1993, and 1994 in the area of ultraviolet remote sensing of the Earth's thermosphere and ionosphere. The emphasis is on space-borne passive sensors being developed as part of global space weather systems. The intent is to document the progress in this field since publication of two books by the author, Huffman, 1992a, 1993. As a part of this review, recent progress and also current technical measurement challenges are discussed.

Long-term radiometric accuracy is a fundamental requirement for future measurement of solar and terrestrial atmospheric EUV emissions from space. Since remote sensing of EUV radiation will become an important measuring technique to explore the thermosphere, new methods have to be established to trace calibration changes of EUV instrumentation, too. With the proposed satellite ATON (Egyptian god of the sun) the solar energy input and other important thermospheric/ionospheric parameters (O₂, O, O⁺, N₂, N⁺, NO, H, He, N_e, T_n, X-rays, solar EUV energy, polar energies) shall be measured based on absolute in-flight calibration of solar and airglow instrumentation. The model payload consists of (1) auto-calibrating solar EUV spectrometers, (2) airglow-solar spectrometer, (3) airglow spectrometer (high spectral resolution), (4) EUV photometers (high data statistics), (5) radio beacon experiment and (6) photocathode arrangement (the latter to detect short-lived solar phenomena of aeronomic interest). The basic measuring concept and instrumental details are presented.

The status of the imaging camera for the spectrum UV space telescope (a 170 cm UV telescope to be built by the space agencies of Canada, Germany, Italy, Russia and Ukraina) is briefly reported. The concept of this camera is to have a double focal length choice on the same detector. This is accomplished via a single flat mirror for the low-resolution (F/10), wide-field channel and by an optical relay located in the filter wheel for the long focal length (F/100), high resolution channel. The detailed shape and position of the detector and the flat mirror have been fixed on the basis of mechanical and focal plane occupation constraints. In the framework of providing a tool for the simulation and planning of astronomical observations with such a space-facility, the expected average PSF has been computed, using Fourier techniques, at different positions in the field of view and at various wavelength bands. Due to the uncertainty on many parameters of the spectrum UV telescope, care has been taken to ensure the modularity of the adopted procedure.

Some preliminary optical designs for three wide field cameras are briefly reported for the space missions Plures and Rosetta. Plures is a proposal to the European Space Agency (ESA) for a wide field telescope able to detect Supernova explosions with a time resolution of the order of a fraction of a minute. After the Supernova detection the telescope should switch to a narrow, single-object mode in order to probe the event in a photometric and spectroscopic mode. Plures should continuously monitor the Virgo cluster with a field of view of the order of 100 squared degrees. Rosetta is a cornerstone mission of ESA for the approaching of a cometary body, after the fly-by with two asteroids. In the approach phase Rosetta should orbit around the comet. Two cameras will map and probe the surface of the comet nucleus. For the three optics all-reflective unobstructed solutions are presented.

The far ultraviolet cameras experiment (NRL-803), part of the U.S. Air Force Space Test Program's AFP-675 payload, flew aboard the space shuttle Discovery in April - May 1991 (STS-39). While in orbit, the experiment gathered data about sources of far-ultraviolet radiation in near-Earth and distant space. To obtain quantitative information from the data, pre-flight and post-flight calibrations of the flight instruments were required. Calibrations were performed using a vacuum-UV optical collimator and two types of light sources: (a) a vacuum-UV monochromator, whose output wavelength could be varied over the wavelength range 105 - 200 nm; and (b) gas discharge tubes with interference-filter windows, giving monochromatic output at selected wavelengths within this range. Calibrations were of two types (the first performed only before flight): (a) using the far UV cameras as photodiodes; and (b) using the cameras to record images on film, as during flight. In addition, in-flight calibrations are obtained from observations of hot stars or other sources which have been measured by previous space experiments. Results from the calibrations are used to derive absolute far-UV brightnesses of objects from the actual flight data.

The design and expected measurements of the atmospheric ultraviolet radiance analyzer (AURA), a satellite experiment, are presented. The goal of AURA is to provide global measurements of the ultraviolet emissions (1150 angstrom to 1900 angstrom) from the Earth's atmosphere. These measurements will include spectra and images. AURA is expected to fly in a near circular, high inclination angle orbit. AURA is designed to have sufficient sensitivity to observe relatively weak emissions in the nighttime tropical arcs or the diffuse aurora. It will also provide excellent signal-to-noise measurements of the day airglow and discrete auroral arcs. The measurements will provide information on atmospheric background emissions and can be used to test remote sensing techniques for ionospheric parameters such as electron density profiles. The AURA instrument provides two channels of UV observations. Each channel uses a 1/8 meter Ebert-Fastie spectrometer mated to a telescope with a scanning mirror. The scan mirrors and grating angles are precisely controlled by stepper motors and use optical fiducials to determine absolute positioning. The two channels operate independently in mode (imaging, spectral, or photometer), viewing direction, and observed wavelength. The field-of-regard of these channels is a 180 degree(s) swatch, centered on nadir, perpendicular to the orbital path (spacecraft velocity vector). The angular field-of-view of these channels will be approximately 2.0 degree(s) by 0.2 degree(s). From the orbital altitudes anticipated (approximately 700 to 1000 km), this will provide higher spatial resolution than previous auroral images from spacecraft.

Short wavelength terrestrial backgrounds (STB) clutter experiments will be performed by the Midcourse Space Experiment (MSX) satellite using the ultraviolet and visible imagers and spectrographic imagers (UVISI) system. These experiments will obtain both temporal and spatial atmospheric statistics in nadir-looking geometries. A comprehensive database will be acquired and used to quantify variations in the background clutter due to changing viewing geometries and dynamic atmospheric conditions. This database will be used to validate radiance and clutter prediction models such as those used in systems design studies. A systematic pipeline approach has been designed to process and analyze the data. Images will be sorted into fixed passband data and spectrographic images. The full-frame images and sub- frame images will be described by a set of structure model parameters which are in the same format as the NSS (non-stationary stochastic structure) model utilized to model atmospheric IR structure. The statistical parameters will constitute the reduced data products. The approach is dictated by the large volume of data anticipated (> 2 Terabytes) and will report the UV clutter data in the same format as the IR-band clutter measured by the Spirit-III sensor.

The Backgrounds Data Center (BDC) is the designated archive for backgrounds data collected by Ballistic Missile Defense Organization (BMDO) programs, some of which include ultraviolet sensors. Currently, the BDC holds ultraviolet data from the IBSS, UVPI, UVLIM, and FUVCAM sensors. The BDC will also be the prime archive for Midcourse Space Experiment (MSX) data and is prepared to negotiate with program managers to handle other datasets. The purpose of the BDC is to make data accessible to users and to assist them in analyzing it. The BDC maintains the Science Catalog Information Exchange System (SCIES) allowing remote users to log in, read or post notices about current programs, search the catalogs for datasets of interest, and submit orders for data. On-site facilities are also available for the analysis of data, and consist of VMS and UNIX workstations with access to software analysis packages such as IDL, IRAF, and Khoros. Either on-site or remotely, users can employ the BDC-developed graphical user interface called the Visual Interface for Space and Terrestrial Analysis (VISTA) to generate catalog queries and to display and analyze data. SCIES and VISTA permit nearly complete access to BDC services and capabilities without the need to be physically present at the data center.

OBPAC is a software package designed to give a general user execution control over a suite of well-tested first principles and empirical modeling codes for atmospheric radiances; the GUI includes modules for visual examination of model results and archival to user-created databases. The calculations and visual displays are tailored to specific situations via a wide variety of inputs. The primary end-results are radiance spectra spanning the wavelength range 110 - 1000 nm at 0.1 nm resolution along user-specified look directions, from which limb profiles over user-specified wavelength intervals are derived; for both, the specific emission components underlying the total radiance can be displayed. In addition, various model inputs and intermediate results are available for graphical inspection. OBPAC has been developed for the prediction and analysis of satellite data acquired with a spectrographic imaging system (SPIMS); procedures for converting model radiances to SPIMS output are also included to facilitate experiment planning. OBPAC is presently limited to dayglow and Rayleigh-aerosol scattering radiances. In this paper, the suite of codes included within OBPAC is described and examples of the application of the package are presented.

A recently developed technique for analyzing single scan auroral limb is applied to simulated auroral limb data. The analysis technique utilizes a detailed fitting procedure in conjunction with an auroral model to provide distributions of auroral energy characteristics over an observing region. If no information on the location of auroral forms is available the fitting procedure provides the most probable precipitating electron spectral characteristics and the spatial distributions of this precipitation. If additional information specifies the distribution of auroral forms in the observing region, we demonstrate that the fitting procedure can extract the characteristic energies of the corresponding auroral forms to a high degree of certainty.

This paper details recent advances in modeling and imaging capabilities since the work of Cox et. al. and Strickland et. al. The emphasis of current work is on simulating imaging data to be obtained by instruments such as SSUSI (spectral sensor ultraviolet spectrographic imager) on DMSP (Defense Meteorological Satellite Program), UVISI (ultraviolet and visible imaging and spectrographic imagers) on MSX (Midcourse Space Experiment) and GUVI (global ultraviolet imager), an instrument selected for NASA's TIMED mission. Some of the modeling capability to be discussed is presently being used to analyze dynamics explorer far ultraviolet images. Modeling improvements include the ability to efficiently calculate radiances as a function of solar azimuth in addition to zenith viewing angle, to calculate radiances for non-spherical density distributions of absorbing species, to input new model atmospheres, ionospheres, and auroral oval precipitation parameters, and finally, to access our radiance models through a much improved user-interface within a windows environment. Key improvements to our imaging software allow for limb and disk emission in global displays, easier mapping of information onto any one of several projections, and displaying simulated dayglow, nightglow, and aurora in full orbit `strip' images (distance along the orbit versus cross-track look angle or distance) as will be obtained by SSUSI. The above improvements are discussed with the aid of figures which show important solar azimuth effects, simulated global DE-1 130.4 nm data, geometrical projections that allow one to visualize the portion of the globe viewed by a low Earth polar orbiting sensor like SSUSI, and full orbit images of simulated SSUSI disk and limb data.

Several different monitoring networks using spectroradiometers are being developed to detect changes in the solar ultraviolet irradiance at the surface of the earth due to stratospheric ozone depletion. To ensure the accurate, long-term measurements that are required from these networks, a strategy for instrument intercomparisons is necessary. This involves the characterization of the instrument parameters which affect measurements of solar ultraviolet irradiance, particularly the linearity, wavelength accuracy, irradiance responsivity, slit- scattering function, and cosine response of the instrument. We have developed laboratory techniques for determining each of these parameters and have used them to characterize a specific spectroradiometer. These techniques and results are being used to develop a strategy for a planned field intercomparison of instruments from several monitoring networks.

The Australian Radiation Laboratory (ARL) has been involved for many years in the measurement of solar ultraviolet radiation (UVR) using spectroradiometers and a network of broadband detectors at 20 sites in Australia and Antarctica. Measurement sites range from polar to tropical, with vastly different weather conditions and as a result there are many difficulties associated with maintenance of the network to ensure accurate and reliable data collection. Calibration procedures for the various detector systems involve simultaneous spectral measurements using a portable spectroradiometer incorporating a double monochromator, calibrated against 1000 watt standard lamps traceable to the CSIRO National Measurement Laboratory. The spectroradiometer was also checked when ARL participated in an international intercomparison of spectroradiometers at Lauder, NZ in February 1993 and a further intercomparison takes place in Germany during 1994. Detector-datalogger systems are intercompared at the Yallambie site for a number of months before installation at another site. As an additional check on the calibrations, computer models of solar UVR at the earth's surface for days with clear sky and known ozone are compared with the UV radiometer measurements. This paper details many of the procedures and difficulties and presents some measurement results. Network data are used to determine the ultraviolet radiation (UVR) levels to which the Australian population is exposed, in educating the public with presentation of the daily UVB on the news/weather reports in the capital cities each evening, as input for epidemiological studies of skin cancer rates and for personal dosimetry studies using polysulphone film.

This paper reports on the transmission by a thin silver filter of the UV-B band, and on the suitability of this filter for use in combination with a silicon photodiode to make a simple, versatile detector for the UV-B band. The UV-B band, from 280 to 320 nanometers, is considered the most dangerous region of ultraviolet sunlight which reaches the earth's surface, since it is the most likely UV radiation to cause skin cancer. Skin cancer cases are increasing, and the increase is linked to increased surface UV radiation due to the thinning levels of stratospheric ozone. Thus, there is a need to develop simple methods for monitoring UV-B. The fortuitous transmission of silver films in the UV-B band, known to the authors from a single reference, has apparently been overlooked in recent instrumentation papers. The transmission and detectivity measurements given here indicate that thin silver films may indeed have a use in simple UV-B exposure meters.

The designs of two spectral scanning radiometric instruments intended for the measurement of solar UV irradiance are described. The higher performance spectroradiometer is intended to provide stable spectral irradiance data for long term UV-B trends detection. This is based on a flight-qualified double monochromator with exceptional wavelength stability, modified to improve the wavelength readout accuracy. The moderate performance spectroradiometer is suitable for less stringent spectral irradiance measurements, e.g., for solar UV-B effects work. Both instruments employ low-noise bialkali photomultiplier tube detectors and photon counting. These instruments are weatherproof, and are designed for reliable operation in the open, exposed to sun and weather.

Spectral radiance calibrations have been made for several SBUV/2 instruments using techniques based upon an internally illuminated spherical integrator and diffuse reflectance panels with BRDF measurements from NIST. Both techniques are referenced to NIST standards of spectral irradiance which are used to derive the spectral irradiance calibrations of the instruments. The spectral radiance of the aperture of the internally illuminated spherical integrator also has been calibrated by NIST against a high temperature blackbody. The consistency of the spectral radiance calibrations and the problems specific to each of the techniques are described.

The space telescope imaging spectrograph (STIS), a next-generation instrument for the Hubble Space Telescope, has fabricated several engineering model units (EMUs) of the multi-anode microchannel array (MAMA) detectors. Good tube yields have been realized in producing these EMUs and some have performances suitable for flight. One of these EMU MAMAs has been operated for substantial periods of time after having undergone both shake and thermal environmental testing. A second will undergo similar environmental tests later this year. An earlier demonstration tube has been used extensively for over a year to evaluate STIS gratings in the Goddard Diffraction Grating Evaluation Facility. The STIS MAMA detectors have now matured to the point where half of the total test and evaluation effort is concerned with the characterization of subtle processes, a level of characterization needed to achieve data with a signal-to-noise ratio in excess of 100. We present test results from these EMUs including detailed analysis of data collected with vacuum chambers specifically designed for the evaluation of these detectors.

The space telescope imaging spectrograph (STIS) is currently being developed for in-orbit installation onto the Hubble Space Telescope in 1997, where it will cover the wavelength range from 115 to 1000 nm in a variety of spectroscopic and imaging modes. For coverage of the 305 - 1000 nm region (and backup of the 165 - 305 nm) region, STIS will employ a custom CCD detector which has been developed at Scientific Imaging Technologies (SITe; formerly Tektronix CCD Products Group). This backside-illuminated device incorporates a proprietary SITe backside treatment and anti-reflective coating to extend the useful quantum efficiency shortward of 200 nm. It also features low noise amplifiers, multi-pinned-phase implants, mini-channel implants, and four quadrant readout. The CCD is thermo-electrically cooled to an operating temperature of -80 degree(s)C within a sealed, evacuated housing with its exterior at room temperature to minimize the condensation of absorbing contaminants in orbit. It is coupled to a set of low noise, flexible, fault-tolerant electronics. Both housing and electronics are being developed by the STIS prime contractor, Ball Aerospace & Communications Group. We describe here the design features, performance, and fabrication status of the STIS CCD and its associated subsystem, along with results of radiation testing.