Absolute Spectral Sensitivity Research Articles

Absolute calibration of the spectral sensitivity of an x-ray streak camera over the 0.1-10keV spectral range equipped with CsI photocathode.

In this paper, we report the absolute measurement of the spectral sensitivity of a bilamellar tube x-ray streak camera (XRSC) over the 0.1-10keV range equipped with a CsI photocathode for Laser MégaJoule (LMJ) fusion experiments. This calibration of the XRSC is performed in static mode by using two multi-anode x-ray generators. Two silicon drift detectors (SDDs) previously calibrated at the Physikalisch-Technische-Bundesanstalt radiometric laboratory are used as secondary standards. Both x-ray generators work with a specific monochromator for radiometric measurements. In the sub-keV region, a 1 m-grazing incidence Rowland geometry monochromator specifically developed to handle LMJ's x-ray camera is used, whereas for higher energies (>2keV), a double-crystal monochromator is employed. The absolute spectral sensitivity of the XRSC is obtained by comparing the CCD counts of the XRSC output with the output counts in x-ray lines recorded by the SDD. The results obtained below 1.2keV are, to our knowledge, the first measurements of the spectral sensitivity of an XRSC in the soft x-ray range with a CsI photocathode. Comparison with a model describing the spectral dependence of the sensitivity of the XRSC revealed that measurements obtained in the sub-keV region are greater than expected, whereas they agree with the model above 4.5keV. There may be several contributors to this behavior, including the grain morphology of the CsI layer and exposure to air.

Metrological studies of the characteristics of multilayer surface coatings using synchrotron radiation

The investigations of multilayer surface nanostructures characteristics was performed with synchrotron radiation sources, characterized by an intensive, calculated continuum. It plays an important role in nanoelectronics metrological base. The main research were carried out at electron storage rings «Siberia-1» (Kurchatov Institute) and MLS (PTB, Berlin) with low electron energy, in a wide wavelength range, including visible range, AUV, VU, EUV and to exclude the X-ray radiation influence. The methods of the radiometers, photodiodes, filters and multilayer mirrors characteristics measurements are based on the synchrotron radiation absolute spectral characteristics and accelerated electrons number variation. The metrological investigations with synchrotron radiation was concentrated on: – absolute spectral responsivety of silicon photodiodes with multilayer filters for integral radiometers applications; – spectral transmittances of surface layers of photodiodes in the extreme ultraviolet region; – spectral reflectance coefficient of superlattice. The characteristics of photodiodes and filters on a synchrotron radiation source are measured using a monochromator and a reference detector. The use of a synchrotron radiation channel makes it possible to study the spectral transmittance of thin films and multilayer structures formed in the in situ mode. To form multilayer nanostructures directly on the receiving surface of photodetectors, an ion-plasma sputtering module is used. The optical scheme of the channel provides for the possibility of using monochromators of grazing incidence for the range of photon energies from 25 to 100 ev and normal incidence for the range of photon energies from 4 to 25 ev. At a photon energy of 40 ev, the absolute spectral sensitivity was 70 ma / W for a photodiode with a surface multilayer filter applied. To develop an experimental technique for measuring the spectral reflection coefficient of multilayer mirrors, and to create standard samples, the Mo/Si system was studied. Computer modeling of multi-layer coatings allows us to calculate the optical characteristics of superlattices in the extreme ultraviolet region. The obtained results of measurements of the spectral reflection coefficient of a multilayer coating in the photon energy range of 65–100 ev indicate a resonance reflection character with a max-imum at an energy of 83.5 ev and an energy width at a half-height of about 6.5 ev. The working wave-length of the reflecting mirror corresponds to the calculated one, which confirms the effectiveness of the adopted model.

Isoperiodic GaxIn1 –xSbyAszP1 –y–z/InP Heterostructures for Planar p–n Photodiodes

Isoperiodic GaxIn1 – xSbyAszP1 – y – z/InP heterostructures for the operation at a wavelength of 1.06–1.60 μm are obtained using the method of zone crystallization with a temperature gradient. An absolute spectral sensitivity of about 0.59 A/W and a response time of about 10 ns are achieved. The threshold sensitivity of the created photodiodes is in the range of 2 × 10–10–5 × 10–11 W at a signal-to-noise ratio of 10.

Изопериодические гетероструктуры Ga-=SUB=-x-=/SUB=-In-=SUB=-1-x-=/SUB=-Sb-=SUB=-y-=/SUB=-As-=SUB=-z-=/SUB=-P-=SUB=-1-y-z-=/SUB=-/InP для планарных p-n-фотодиодов

Isoperiodic heterostructures GaxIn1-xSbyAszP1-y-z/InP at a 1.06 to 1.6 μm wavelength interval were grown by the method of floating-zone recrystallization with temperature gradient. Absolute spectral sensitivity of ~ 0.59 A/W and a speed of ~ 10 ns were achieved. Threshold sensitivity for the fabricated photodiodes was in the range 2·10^-10 to 5·10^-11 W with a signal-to-noise ratio of 10.

National Primary Standard for the Units of Absolute and Relative Spectral Sensitivity at Wavelengths from 0.25 TO 14.00 μm Get 213–2014

This is a discussion of the characteristics of a cryogenic radiometer and monochromatic radiation source that form part of the National primary standard GET 213–2014 for the units of absolute and relative spectral sensitivity at wavelengths from 0.25 to 14.00 μm and are intended for calibration of photodetectors with respect to spectral sensitivity.

Collision-induced emission of singlet oxygen in the visible spectral region at temperatures of 90–315 K

Collision-induced emission of singlet oxygen molecules is studied using spectrometers calibrated for absolute spectral sensitivity. The collision-induced emission-rate constants at wavelengths of 479, 514, 577, 634, and 703 nm are determined within the temperature range 90–315 K. It is found that the intensities of the emission bands increase with decreasing temperature below 100 K. The interrelation between the collision-induced emission-rate constants and the intensities of the collision-induced absorption bands is discussed. The Einstein coefficients for spontaneous emission of excited free O2: O2 complexes are estimated.

Simulation and investigation of the GaAs and GaSb photovoltaic cell performance

The current-voltage and power-voltage characteristics of GaAs and GaSb PVCs under illumination are simulated for different values of the series resistance, temperature, and diode parameter, and the absolute spectral sensitivity of these devices is investigated. It is found that the open-circuit voltage depends mostly on the diode parameter and temperature, whereas the efficiency of the PVC is influenced by the series resistance and diode parameter. It is shown that GaAs and GaSb PVCs can be successfully used in cascade solar cells for conversion of concentrated solar radiation.

BIOLOGICAL WEIGHTING FUNCTIONS FOR UV INHIBITION OF PHOTOSYNTHESIS IN THE KELP LAMINARIA HYPERBOREA (PHAEOPHYCEAE)(1).

Different wavelengths of sunlight either drive or inhibit macroalgal production. Ultraviolet radiation (UVR) effectively disrupts photosynthesis, but since UVR is rapidly absorbed in coastal waters, macroalgal photoinhibition and tolerance to UVR depend on the depth of attachment and acclimation state of the individual. The inhibition response to UVR is quantified with a biological weighting function (BWF), a spectrum of empirically derived weights that link irradiance at a specific wavelength to overall biological effect. We determined BWFs for shallow (0 m, mean low water [MLW]) and deep (10 m) Laminaria hyperborea (Gunnerus) Foslie collected off the island of Finnøy, Norway. For each replicate sporophyte, we concurrently measured both O2 evolution and (13) C uptake in 48 different light treatments, which varied in UV spectral composition and irradiance. The relative shape of the kelp BWF was most similar to that of a land plant, and the absolute spectral weightings and sensitivity were typically less than phytoplankton, particularly in the ultraviolet radiation A (UVA) region. Differences in BWFs between O2 and (13) C photosynthesis and between shallow (high light) and deep (low light) kelp were also most significant in the UVA. Because of its greater contribution to total incident irradiance, UVA was more important to daily loss of production in kelp than ultraviolet radiation B (UVB). Photosynthetic quotient (PQ) also decreased with increased UVR stress, and the magnitude of PQ decline was greater in deepwater kelp. Significantly, BWFs assist in the comparison of biological responses to experimental light sources versus in situ sunlight and are critical to quantifying kelp production in a changing irradiance environment.

Calibration Procedures for X-ray Streak Cameras and Elements of X-ray Measuring Circuits

Setups developed for the calibration of X-ray streak cameras and of elements of X-ray measuring circuits are described. Calibration procedures are described and calibration results related to the absolute spectral sensitivity, spatial resolution, distortion, sensitivity nonuniformity over the screen, sweep speed and nonlinearity of an X-ray streak camera, as well as the results of the calibration of filters and mirrors used in recording laser-plasma X-rays are presented. The absolute-calibration error for the streak camera is within ±10%, and the calibration error for the filter and mirrors is within ±2%. Methods for processing photochronograms are described that, using the calibration data, allow the correction of distortions introduced by the streak camera.

Radiometric calibration of the telescope and ultraviolet spectrometer SUMER on SOHO

The prelaunch spectral-sensitivity calibration of the solar spectrometer SUMER (Solar Ultraviolet Measurements of Emitted Radiation) is described. SUMER is part of the payload of the Solar and Heliospheric Observatory (SOHO), which begins its scientific mission in 1996. The instrument consists of a telescope and a spectrometer capable of taking spatially and spectrally highly resolved images of the Sun in a spectral range from 50 to 161 nm. The pointing capabilities, the dynamic range, and the sensitivity of the instrument allow measurements both on the solar disk and above the limb as great as two solar radii. To determine plasma temperatures and densities in the solar atmosphere, the instrument needs an absolute spectral-sensitivity calibration. Here we describe the prelaunch calibration of the full instrument, which utilizes a radiometric transfer-standard source. The transfer standard was based on a high-current hollow-cathode discharge source. It had been calibrated in the laboratory for vacuum UV radiometry of the Physikalisch-Technische Bundesanstalt by use of the calculable spectral photon flux of the Berlin electron storage ring for synchrotron radiation (BESSY)-a primary radiometric source standard.

Measurements of the absolute spectral sensitivity of X-ray semiconductor detectors in the photon energy range of 1.5–15 keV using “white” SR beam of the VEPP-3 storage ring

Results of measurements of the absolute spectral sensitivity of silicon semiconductor detectors in the X-ray quanta energy range of 1.5–15 keV are presented. The detectors, being calibrated, were placed into the direct “white” synchrotron radiation (SR) beam from the VEPP-3 storage ring. The spectrum of X-radiation at the entrance window of the detectors was changed by using sets of calibrated filters, as well as by varying the energy of the electrons in the storage ring. The possibility of accurate calculation of the SR spectrum on the calibrated detector under its irradiation in different conditions allowed us to determine the detector spectral sensitivity from a set of integral equations connecting the spectral sensitivity to the registered detector currents. The analysis of possible experimental errors indicates that the absolute spectral sensitivity of the detectors was restored with an accuracy of not worse than 10% in the total photon energy range under the study.

Specialization of retinal function in the compound eyes of mantis shrimps

Visual function and its specialization at the level of the retina were studied in 13 species of stomatopod crustaceans, representing three superfamilies: Gonodactyloidea, Lysiosquilloidea, and Squilloidea. We measured attenuation and irradiance spectra in the environment of each species, at the actual depths and times of activity where we observed individuals. We also characterized die intrarhabdomal niters of all study species and determined the absolute spectral sensitivity functions and approximate photon capture rates of all photoreceptor classes below the level of the 8th retinular cell in seven of these species. Shallow-water gonodactyloid species have four distinct classes of intrarhabdomal filters, producing photoreceptors that are relatively insensitive but which have the broadest spectral coverage of all. Deep-water gonodactyloids and all lysiosquilloids have filters that are spectrally less diverse. These species often discard the proximal filter classes of one or more receptor types. As a result, their retinas are more sensitive but have reduced spectral range or diversity. The single squilloid species has the most sensitive photoreceptors of any we observed, due to the lack both of intrarhabdomal filters and tiered photoreceptors. Photon absorption rates, at the times of animal activity, were similar in most photoreceptor classes of all species, whether the receptors were tiered or untiered, or filtered or unfiltered. Thus, the retinas of stomatopods are specialized to operate at similar levels of stimulation at the times and depths of actual use, while evidently maintaining the greatest possible potential for spectral coverage and discrimination.

Hollow Cathode Transfer Standards for the Radiometric Calibration of VUV Telescopes of the Solar and Heliospheric Observatory (SOHO)

On board the ESA/NASA space mission SOHO (Solar and Heliospheric Observatory) there will be several VUV telescope/spectrometer systems to observe the solar disk and its corona in the wavelength range 15 nm to 160 nm. To determine the absolute spectral sensitivity of these instruments prior to launching, transfer source standards have been developed. These transfer standards consist of a high-current hollow cathode source combined with collimating optics. One standard uses a concave mirror at normal incidence for the wavelength range 50 nm to 160 nm and the other standard uses Wolter type II grazing incidence optics for the range 16 nm to 80 nm. These transfer source standards are calibrated against the electron storage ring BESSY as a primary radiometric source standard.

Measurements of absolute sensitivity of semiconductor detectors for 7–20 keV x rays using synchrotron radiation of VEPP-3 storage ring

Results of measurements of the absolute spectral sensitivity of silicon semiconductor detectors for 7–20 keV x rays are presented. Synchrotron radiation from a 2-T wiggler, installed at the VEPP-3 storage ring, was used for this study. Two quite different approaches were applied to measure the detector spectral sensitivity. According to the first approach, the measurements were performed in monochromatic radiation. The absolute photon flux was determined by a scintillation counter with known detection efficiency and monitored by a transmission ionization chamber. The second approach corresponds to the measurements in a ‘‘white’’ synchrotron radiation beam through sets of known absorption filters and via the following unfolding of the spectral sensitivity from a set of integral equations. The experimental results obtained by both procedures are in good agreement. The accuracy of the experimental calibration procedures is assumed to be not worse than 10%.

Absolute spectral sensitivity of linear-photodiode arrays in 7–20 keV energy x-ray range

This paper deals with the study of the absolute spectral sensitivity of linear photodiode arrays (of LF1024-25/2 type) as x-ray one-coordinate detectors within the 7–20 keV energy range. The threshold sensitivity of such detectors was estimated in the indicated range. The measurements were made using synchrotron radiation from the VEPP-3 storage ring.

Calibration of the absolute spectral sensitivity of a solar UV radiometer with the use of synchrotron radiation

The absolute spectral sensitivity calibration of a solar UV radiometer, intended for use on board a satellite for measuring solar illuminance at the H Lyα wavelength of 121.6 nm, has been carried out against a standard based on a synchrotron radiation source. The estimated overall calibration error is 2.8% (rms).

シリコンポトダイオードの分光応答度の推定

This paper is concerned with measuring method of the absolute spectral sensitivity of photodiodes. This is generally made possible with simple equipment by the self-calibration method of quantum efficiency published rece ntly by J. Geist, et al with NBS. Applying this method to photodiodes on the market, several practical problems were investigated.A mutual comparative method suitable for the measurement of surface reflectance of photodiodes was introduced, and the relation between incident angle and quantum efficiency was studied.

Determination of the absolute spectral sensitivity of weakly selective detectors using a model black body

Determination of the absolute spectral sensitivity of weakly selective detectors using a model black body

Absolute spectral sensitivity at different eccentricities.

Absolute spectral-threshold functions were measured during the cone-plateau period and in a dark-adapted state at 0, 6, 17, 28, 45, and 65 degrees temporally to the fovea. It was found that, when the photopic functions were brought together at 660 nm, they closely coincided in the 520-700-nm region of the spectrum, irrespective of location, suggesting that the relative spectral sensitivity and the weighted contributions of the middle-and long-wave cone photopigments remain invariant across the retina. On the other hand, the results suggest that the relative contribution of the short-wave cone mechanism increases between fovea and 17 degrees, stays essentially constant between 17 and 28 degrees, and decreases between 28 and 65 degrees. Furthermore, the results suggest that the absolute sensitivity of the middle- and long-wave cones decreases between fovea and 65 degrees, whereas the absolute sensitivity of the rods increased form fovea to 17 degrees and decreases between 17 and 65 degrees degrees. Finally, the log difference between the absolute dark-adapted cone and the rod threshold was found to increase between fovea and 45 degrees and to decrease between 45 and 65 degrees.

MEASUREMENT OF MINUTE RADIOMETRIC QUANTITIES IN THE SPECTRAL RANGE FROM VISIBLE TO NEAR INFRA-RED

This paper describes a method of calibrating the absolute spectral sensitivity of silicon photovoltaic cell. The cell was used for measuring minute radiant power, irradiance and radiant intensity of radiations, ranging from 0.4 μm to 1.1 μm. It was also used for measuring the external quantum efficiency of electroluminescent devices. The sensitivity of the system is higher than that of the conventional thermopile by three orders of magnitude. By incorporating with an integral sphere, it is very convenient to measure the radiant power, ranging from 6.3 nW to 310 mW, of any uniformly or non-uniformly distributed source.The maximum spectral efficiency Km was determined by using this system, and the accuracy of radiometrie system and photometric system was discussed. Finally, the measured optical parameters of some light-emitting diodes were examined.