Intercomparison of far-infrared transmittance measurements.

We present the results of the first systematic "round-robin" comparison of far-infrared transmittance spectra measurements, which was performed by five laboratories and piloted by Physikalisch-Technische (PTB). The transmittance spectra of four different samples were measured by the participating laboratories in the 600 cm to 10 cm range (16.67 µm to 1000 µm) in a blind comparison.

Background corrected measurements of optical quantities in the far-infrared spectral range.

By definition, optical quantities transmittance and reflectance can basically be determined as the ratio of two flux measurements. One measurement is performed with, and the other without, the sample under test in the optical path. However, at longer wavelengths the temperature radiation of the sample itself as well as of the applied spectrometer and detector increasingly contribute to the detected radiation budget.

A large-area plate radiator with in situ temperature homogenization for thermographic imager calibration.

Large-area plate radiators with a high emissivity and uniform temperature distribution are needed as reference sources for calibrating infrared imagers and camera systems. However, achieving very uniform temperature distribution over a large area is technically challenging, especially at high temperatures. We present a large-area plate radiator with an improved uniformity in its surface temperature distribution for the calibration of infrared thermographic imagers.

Report on the CCT Supplementary Comparison S1 of Infrared Spectral Normal Emittance/Emissivity.

The National Measurement Institutes (NMIs) of the United States, Germany, France, Italy and Japan, have joined in an inter-laboratory comparison of their infrared spectral emittance scales. This action is part of a series of supplementary inter-laboratory comparisons (including thermal conductivity and thermal diffusivity) sponsored by the Consultative Committee on Thermometry (CCT) Task Group on Thermophysical Quantities (TG-ThQ). The objective of this collaborative work is to strengthen the major operative National Measurement Institutes' infrared spectral emittance scales and consequently the consistency of radiative properties measurements carried out worldwide.

Planar hyperblack absolute radiometer.

The absolute responsivity of a planar cryogenic radiometer fabricated from micromachined silicon and having carbon nanotubes, as the absorber and thermistor were measured in the visible and far infrared (free-field terahertz) wavelength range by means of detector-based radiometry. The temperature coefficient of the thermistor near 4.8 K and noise equivalent power were evaluated along with independent characterization of the window transmittance and specular reflectance of the nanotube absorber.

Three-element trap filter radiometer based on large active area silicon photodiodes.

This paper shows the opto-mechanical design of a new filter radiometer built at the Physikalisch-Technische Bundesanstalt, Germany, for the accurate determination of the thermodynamic temperature of high-temperature blackbodies. The filter radiometer is based on a three-element reflection-type trap detector that uses three large active area silicon photodiodes. Its spectral coverage and field of view are defined by a detachable narrow-band filter and a diamond-turned precision aperture, respectively.

Nonuniformity correction of imaging systems with a spatially nonhomogeneous radiation source.

We present a novel method of nonuniformity correction of imaging systems in a wide optical spectral range by applying a radiation source with an unknown and spatially nonhomogeneous radiance or radiance temperature distribution. The benefit of this method is that it can be applied with radiation sources of arbitrary spatial radiance or radiance temperature distribution and only requires the sufficient temporal stability of this distribution during the measurement process. The method is based on the recording of several (at least three) images of a radiation source and a purposeful row- and line-shift of these sequent images in relation to the first primary image.

A highly linear superconducting bolometer for quantitative THz Fourier transform spectroscopy.

A superconducting transition edge sensor (TES) bolometer operating in the spectral range from 0.1 THz to 3 THz was designed. It is especially intended for Fourier transform spectroscopy and features a higher dynamic range and a highly linear response at a similar response compared to commercially available silicon composite bolometers.

Method for the calibration of the spectral irradiance of tungsten filament transfer standard sources traceable to synchrotron radiation.

The spectral irradiance calibration of tungsten strip and spiral filament lamps applying synchrotron radiation revealed that the spectral irradiance in the wavelength range from 280 to 400 nm can be well approximated by blackbody radiation according to Planck's law. Consequently, the spectral irradiance of the filament lamp can then be described by an effective irradiance temperature, which would be beneficial for practical measurements. Including the emissivity of tungsten into the approximation, the model can be expanded to visible and near-infrared wavelength regions.

State-of-the art comparability of corrected emission spectra. 2. Field laboratory assessment of calibration performance using spectral fluorescence standards.

In the second part of this two-part series on the state-of-the-art comparability of corrected emission spectra, we have extended this assessment to the broader community of fluorescence spectroscopists by involving 12 field laboratories that were randomly selected on the basis of their fluorescence measuring equipment. These laboratories performed a reference material (RM)-based fluorometer calibration with commercially available spectral fluorescence standards following a standard operating procedure that involved routine measurement conditions and the data evaluation software LINKCORR developed and provided by the Federal Institute for Materials Research and Testing (BAM). This instrument-specific emission correction curve was subsequently used for the determination of the corrected emission spectra of three test dyes, X, QS, and Y, revealing an average accuracy of 6.

State-of-the art comparability of corrected emission spectra. 1. Spectral correction with physical transfer standards and spectral fluorescence standards by expert laboratories.

The development of fluorescence applications in the life and material sciences has proceeded largely without sufficient concern for the measurement uncertainties related to the characterization of fluorescence instruments. In this first part of a two-part series on the state-of-the-art comparability of corrected emission spectra, four National Metrology Institutes active in high-precision steady-state fluorometry performed a first comparison of fluorescence measurement capabilities by evaluating physical transfer standard (PTS)-based and reference material (RM)-based calibration methods. To identify achievable comparability and sources of error in instrument calibration, the emission spectra of three test dyes in the wavelength region from 300 to 770 nm were corrected and compared using both calibration methods.

Optical methods for power measurement of terahertz radiation.

Precision power measurements of terahertz (THz) radiation are required to establish metrological applications in the THz spectral range. However, traceability to the International System of Units (SI) has been missing in the THz region in the past. The Physikalisch-Technische Bundesanstalt (PTB), as the national metrology institute of Germany, determines the spectral responsivity of detectors for THz radiation by using two complementary optical methods: source- and detector-based radiometry.

Intercalibration of SUMER and CDS on SOHO. II. SUMER Detectors A and B and CDS NIS.

Results of an intercalibration between the extreme-ultraviolet spectrometers Coronal Diagnostic Spectrometer (CDS) and Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on board the Solar and Heliospheric Observatory (SOHO) are reported. The results of the joint observing program Intercal_01 are described, and intercalibration results up to July 2000 of both SUMER detectors A and B and of the CDS Normal Incidence Spectrometer (NIS) are presented. The instruments simultaneously observed radiance of emission lines at the center of the Sun, and three lines have been chosen for intercomparison: He i 584 A, Mg x 609 A, and Mg x 624 A.

Radiometric calibration of the vacuum-ultraviolet spectrograph SUMER on the SOHO spacecraft with the B detector.

The Solar Ultraviolet Measurement of Emitted Radiation (SUMER) vacuum-ultraviolet spectrograph was calibrated in the laboratory before the integration of the instrument on the Solar and Heliospheric Observatory (SOHO) spacecraft in 1995. During the scientific operation of the SOHO it has been possible to track the radiometric calibration of the SUMER spectrograph since March 1996 by a strategy that employs various methods to update the calibration status and improve the coverage of the spectral calibration curve. The results for the A Detector were published previously [Appl.

Intercalibration of SUMER and CDS on SOHO. I. SUMER detector A and CDS NIS.

The results of an intercalibration between the extreme ultraviolet spectrometers Coronal Diagnostic Spectrometer (CDS) and Solar Ultraviolet Measurements of Emitted Radiation (SUMER) onboard the Solar and Heliospheric Observatory (SOHO) are presented. During the joint observing program Intercal_01, CDS and SUMER were pointed at the same locations in quiet Sun areas and observed in the same wavelength bands located around the spectral lines He i 584 A, Mg x 609 A, and Mg x 624 A. The data sets analyzed here consist of raster images recorded by the CDS normal-incidence spectrometer and SUMER detector A and span the time from March 1996 to August 1996.

Radiometric Calibration Tracking of the Vacuum-Ultraviolet Spectrometer SUMER During the First Year of the SOHO Mission.

Detailed radiometric calibration tracking of the vacuum-ultravioletspectrometer SUMER (from solar ultraviolet measurements of emittedradiation) was performed during the first year of the Solar andHeliospheric Observatory (SOHO) mission and will continue. Inview of the flight history of many previous solar UV instruments, thestability of calibration of the extreme-ultraviolet instruments on SOHOhas been a major concern. Results obtained during the first year ofoperation show that excellent radiometric stability has been achievedwith SUMER.

Radiometric calibration of SUMER: refinement of the laboratory results under operational conditions on SOHO.

The radiometric calibration of the solar telescope and spectrometer SUMER was carried out in the laboratory before delivery of the instrument for integration into the SOHO (Solar and Heliospheric Observatory) spacecraft. Although this effort led to a reasonable coverage of the wavelength range from 53.70 to 146.

[Cutaneous form of sarcoidosis at the auricle].

Sarkoidosis is a disease of so far unknown etiology that can affect potentially every organ. Sarcoidosis of the lung is the most common form, nevertheless in more than one third of the cases the head and neck area is affected. Manifestations of the disease can be present in lymph nodes of the neck, the middle ear, the pars petrosa of the temporal bone and in the paranasal sinuses as well as in the larynx and pharynx.

Traceability in fluorometry: Part II. Spectral fluorescence standards.

The need for the traceable characterization of fluorescence instruments is emphasized from a chemist's point of view, focusing on spectral fluorescence standards for the determination of the wavelength- and polarization-dependent relative spectral responsivity and relative spectral irradiance of fluorescence measuring systems, respectively. In a first step, major sources of error of fluorescence measurements and instrument calibration are revealed to underline the importance of this issue and to illustrate advantages and disadvantages of physical and chemical transfer standards for generation of spectral correction curves. Secondly, examples for sets of traceable chemical emission and excitation standards are shown that cover a broad spectral region and simple procedures for the determination of corrected emission spectra with acceptable uncertainties are presented.

Traceability in fluorometry--Part I: Physical standards.

The inter-instrument, inter-laboratory, and long-term comparability of fluorescence data requires the correction of the measured emission and excitation spectra for the wavelength- and polarization-dependent spectral irradiance of the excitation channel at the sample position and the spectral responsivity of the emission channel employing procedures that guarantee traceability to the respective primary standards. In this respect the traceability chain of fluorometry is discussed from a radiometrist's point of view. This involves, in a first step, the realization of the spectral radiance scale, based on the blackbody radiator and electron storage ring, and the spectral responsivity scale, based on the cryogenic radiometer and their control via key comparisons of the national metrology institutes.

Nasal breathing and continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea (OSA).

Although nasal continuous positive airway pressure (nCPAP) treatment is the most efficient therapy for obstructive sleep apnea (OSA), compliance with therapy is poor because of several side effects. Among these adverse effects some are related to the reactions of the nose to nCPAP which are briefly described. In a long-term survey of 109 OSA patients, 80.

[Therapy with nasal CPAP (continuous positive airway pressure) in patients with obstructive sleep apnea syndrome (OSAS). II: Side-effects of nCPAP therapy. Effect on long-term acceptance].

Background: nCPAP is a well established method for the management of OSAS. The aim of this study was to evaluate long-term side effects and complications of nCPAP therapy and their influence on the patients compliance with treatment.

Patients And Methods: Forty-one patients with OSAS were interviewed by questionnaire to elucidate the problems and adverse effects of their nCPAP therapy.

[Therapy with nasal CPAP (continuous positive airway pressure) in patients with obstructive sleep apnea syndrome (OSAS). I: Long-term acceptance of nasal CPAP].

Background: Nocturnal ventilation with nCPAP has been established as the safest and most efficient nonsurgical treatment for OSAS. Long-term results, however, are determined by the patients' compliance with therapy. The aim of this study was the objective measurement of long-term acceptability of nCPAP therapy in all patients receiving this treatment in our sleep laboratory between January 1990 and March 1995.