Relative Spectral Sensitivity Research Articles

PHOTOSENSITIVITY OF PbS COLLOIDAL QUANTUM DOTS BASED NANOSTRUCTURES WITH AN ENERGY BARRIER

A new architecture of photosensitive elements for the near (0.7–1.4 μm) and short-wavelength (1.4–3.0 μm) infrared regions of the spectrum based on hybrid nanostructures consisting of PbS colloidal quantum dots and functional layers of ZnO and AgNW silver nanowires is proposed. Small-sized (12 × 12 μm) photosensitive elements with an energy barrier at the contact between layers of n- and p-type CQDs have been studied. The current-voltage characteristics, spectral dependences of optical absorption and relative spectral photosensitivity of Si(λ)/Si(λmax) barrier structures at room temperature have been studied. It is shown that the proposed architecture of barrier structures provides photosensitivity in a wide spectral range from 0.4 µm to 2.0 µm. An excess of the average value of the relative spectral sensitivity Si(λ)/Si(λmax) about 1.5 times compared to those previously observed in the wavelength range of 0.9–1.85 μm for barrier nanostructures from PbS CQDs was found.

Development of measures for metrological support of Raman spectroscopy

The method of Raman spectroscopy (RS) is widely used for timely metrological support of technological lines of the industrial sector in the chemical, medical and pharmaceutical, food, as well as criminalistics and forensic examinations. The wide application of the Raman spectroscopy method requires the use of specific metrological support tools, namely, measures for calibrating Raman spectrometers and microscopes according to the spectrum shape (i. e. relative spectral sensitivity).The purpose of the research was to develop prototype measures designed to calibrate Raman spectrometers and microscopes on a scale of relative intensities provided with metrological traceability to the SI base units.Prototype measures were made from inorganic glasses based on an oxide matrix, each of the glasses was activated with metal ions selected to excite a broad fluorescence line with radiation at a given wavelength: 532 nm (manganese ions), 633 nm (bismuth ions) and 785 nm (chromium ions). Metrological characteristics were established for prototype measures, where the certified characteristic is the relative intensity of the reproduced fluorescence radiation. The maximum expanded measurement uncertainty of the relative fluorescence intensity at a coverage factor k = 2 was determined, which is 9.4 %, 5.2 % and 2.8 % for prototype measures designed to reproduce the relative fluorescence intensity when excited at wavelengths of 532 nm, 633 nm and 785 nm, respectively.Certification of measures performed on the laser Raman confocal microscope Confotec NR500, which is part of the GET 196-2015 standard, allows establishing metrological traceability through the scale of relative intensities of the GET 8 6-2017 microscope, providing traceability to SI units of the “(light) energy flux” value. Thus, it is possible to find the spectral correction function for determining the Raman spectra traceable to the State Primary Standard GET 196-2015 for calibrated devices using certified measures.The practical significance of the results of the research makes it possible to expand the possibility of establishing and monitoring the stability of the calibration characteristics of microscopes and Raman spectrometers, namely, it allows calibration on a scale of relative intensities.

Multioctave high-dynamic range optical spectrometer for single-pulse, longitudinal characterization of ultrashort electron bunches

We present design and realization of an ultrabroadband optical spectrometer capable of measuring the spectral intensity of multioctave-spanning light sources on a single-pulse basis with a dynamic range of up to eight orders of magnitude. The instrument is optimized for the characterization of the temporal structure of femtosecond long electron bunches by analyzing the emitted coherent transition radiation spectra. The spectrometer operates within the spectral range of 250 nm to $11.35\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$, corresponding to 5.5 optical octaves. This is achieved by dividing the signal beam into three spectral groups, each analyzed by a dedicated spectrometer and detector unit. The complete instrument was characterized with regard to wavelength, relative spectral sensitivity, and absolute photometric sensitivity, always accounting for the light polarization and comparing different calibration methods. Finally, the capability of the spectrometer is demonstrated with a coherent transition radiation measurement of a laser wakefield accelerated electron bunch, enabling to determine temporal pulse structures at unprecedented resolution.

Threshold and spectral sensitivity of vision in medaka Oryzias latipes determined by a novel template wave matching method

We propose a new analytical method for determining the response threshold in electroretinogram (ERG) in which the wave shows a biphasic slow dc-potential shift. This method uses the recorded wave to the highest intensity stimuli in each wavelength tested as a template wave f(t), and it was compared with other recorded waves obtained under lower intensities g(t). Our test recordings in medaka Oryzias latipes were analogous between the template and the compared waveforms, although there were differences in amplitude and time lag (τ, peak time difference) which occurred as a result of the difference in stimulus intensity. Cross-correlation analysis was applied. Based on the obtained cross-correlation function Cfg(τ) in each comparison, τ was determined as the time lag at which the cross-correlation coefficient Rfg(τ) showed the maximum value. Determined thresholds that were based on both the experimenter's visual inspection and this new method agreed well when the adoption condition was set to satisfy R(τ) ≥ 0.7 and τ ≤ 150 ms in scotopic or τ ≤ 120 ms in photopic conditions. We concluded that this “template wave matching method” is a quick and reliable objective assessment that can be used to determine the threshold. This study analyzed ERG recordings in response to 6 kinds of wavelength light stimuli (380 nm to 620 nm) at different photon flux densities. We report the threshold levels and relative spectral sensitivities in scotopic and photopic vision of medaka.

The branching ratio of intercombination [formula omitted]transitions in the RbCs molecule: Measurements and calculations

We observed the A1Σ+∼b3Π→a3Σ+/X1Σ+laser-induced fluorescence (LIF) of the RbCs molecule excited from the ground X1Σ+state by the Ti:Sapphire laser. The LIF spectra from the common perturbed levels of the singlet-triplet A ∼ b complex was recorded by the Fourier-transform (FT) spectrometer with the instrumental resolution of 0.03 cm−1. The relative intensity distribution in the rotationally resolved A∼b→a3Σ+(va)/X1Σ+(vX)progressions was measured, and their branching ratio was found to be about of 1÷5×10−4in the bound region of the a3Σ+and X1Σ+states. The experiment was complemented with the scalar- and full-relativistic calculations of the A/b−X/atransition dipole moments (TDMs) as functions of internuclear distance. The relative systematic error in the resulting ab initio TDM functions evaluated for the strong A−Xtransition was estimated as few percent in the energy region, where the experimental LIF intensities are relevant. The relative spectral sensitivity of the FT registration system, operated with the InGaAs diode detector and CaF beam-splitter, was calibrated in the range [6 500, 12 000] cm−1by a comparison of experimental intensities in the long A ∼ b → X(vX) LIF progressions of the K2 and KCs molecules with their theoretical counterparts evaluated using the ab initioA−XTDMs. Both experimental and theoretical transition probabilities can be employed to improve the stimulated Raman adiabatic passage process, a → A ∼ b → X, which is exploited for a laser assembling of ultracold RbCs molecules.

Retinal phototoxicity and the evaluation of the blue light hazard of a new solid-state lighting technology

Exposure Limit Values (ELV) for artificial lighting were defined in order to prevent light-induced damage to the retina. The evaluation of the lighting devices include the correction of their spectra by the B(λ) function or blue light hazard function, representing the relative spectral sensitivity of the human eye to the blue light. This weighting function peaks between 435 and 440 nm. In this study we evaluate a new generation of light emitting diode (LED), the GaN-on-GaN (gallium nitride on gallium nitride) LED, that present an emission peak in the purple part of the spectrum. Wistar rats were exposed to GaN-on-GaN and conventional diodes at different retinal doses (from 2.2 to 0.5 J/cm2). We show that GaN-on-GaN diodes are more toxic than conventional LED for the rat neural retina and the rat retinal pigment epithelium, indicating that the BLH (blue light hazard) weighting is not adapted to this type of diodes. One of the reasons of this increased toxicity is the effects of shorter wavelengths on mitochondria polarization. We also show that the threshold of phototoxic retinal dose in the rat (fixed at 11 J/cm2, BLH weighted) is overestimated, suggesting that the values used for regulations, calculated in primates using the same methods than in rats, should be revised.

Development of the mathematical model of light flux intensity sensor based on the photodiode and operational amplifier

The article describes a method for interpolating the dependence of the photodiode relative spectral sensitivity on the optical radiation wavelength using a special function that provides interpolation of the experimental dependence with any asymmetry coefficient. A new version of the light flux intensity sensor mathematical model based on a photodiode and an operational amplifier using the proposed interpolation technique has been created. It was found that the interpolation error does not exceed 3–6 %, depending on the type of photodiode and the shape of its experimentally obtained spectral characteristic. The processes occurring in the equivalent circuit of the measuring channel based on the operational amplifier are analyzed. The created mathematical model can be applied to optimize the processes in the measuring channel of the light flux intensity. The research results presented in the article can be used in the design and mathematical modeling of light flux intensity sensors for the needs of various fields of science, industry and medicine.

One or many? Are there benefits for using test batteries for the classification of congenital colour vision deficiencies?

AbstractFor reasons of safety or quality control many professions require their potential employees to have normal colour‐vision. A variety of screening tests for colour‐vision deficiencies (CVD) exist, but there is a clear trade‐off between reliability of diagnoses and practical efficiency. For example, the Ishihara Plates are praised for their high sensitivity, speed and ease of use and are the most common primary test in occupational settings. However, the test does not reliably classify type or severity of known CVDs, different versions may give slightly different results, and false positives are common. On the other hand, the gold standard for characterising CVD is the anomaloscope, where an individual’s Rayleigh match provides an index of the relative spectral sensitivities of the L and M cones and gives a definitive classification of CVD type and severity. However, the instrument is expensive, needs a highly experienced examiner and often requires extended testing time. More recent, sophisticated tests such as the ‘Cambridge Colour Test’ and the ‘Colour Assessment and Diagnosis’ test’ show good selectivity and specificity, but are expensive and therefore not widely used by many employers. Given the variety of choice in standardised tests available to recruiters, the presentation will consider the reliability and consistency in the classifications of CVD for a battery of potential tests.

Improved-Efficiency Irradiation Facility for Poultry Farming

This article discusses the effectiveness of influence of irradiation lighting facility on the productivity and homogeneity of broilers. Irradiation lighting facility of increased efficiency is proposed. Its spectral composition of radiation sources corresponds to the function of relative spectral sensitivity of the organ of vision, and to the functions of relative spectral erythemal and bactericidal efficiency. The results of experiment in the influence of optical radiation, received from irradiation lighting facility, on an industrial herd of broilers are given in the article.

Camera response prediction for various capture settings using the spectral sensitivity and crosstalk model.

In this paper, a camera response formation model is proposed to accurately predict the responses of images captured under various exposure settings. Differing from earlier works that estimated the camera relative spectral sensitivity, our model constructs the physical spectral sensitivity curves and device-dependent parameters that convert the absolute spectral radiances of target surfaces to the camera readout responses. With this model, the camera responses to miscellaneous combinations of surfaces and illuminants could be accurately predicted. Thus, creating an "imaging simulator" by using the colorimetric and photometric research based on the cameras would be of great convenience.

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.

Cone fundamentals: A model for the future of colorimetry

Cone fundamentals is the name given to the relative spectral sensitivity of long-wave sensitive, medium-wave sensitive and short-wave sensitive cones. Cone fundamentals represent the spectral absorptances of the retinal photopigments in the cones multiplied by the spectral transmittances of the ocular media through which light passes to reach the retina. The CIE 2006 cone fundamentals are based on the Stiles and Burch experimental colour matches and have been validated by recent microspectrophotometric measurements and modelling. A new physiologically based version of the MacLeod–Boynton chromaticity diagram is proposed by the CIE as well as a cone-fundamental-based ( xF, yF) chromaticity diagram. All the data necessary to use these concepts for high-precision colorimetric calculations are readily available.

Spatial properties of fundus reflectance and red-green relative spectral sensitivity.

We investigated the spatial characteristics of the diffuse light in the eye at two different wavelengths and the extent to which this may affect red-green relative spectral sensitivity. The fundus reflectance of six subjects was measured for different field sizes ranging from a 0.18° to 7.28° radius and for two different wavelengths, 560 and 650 nm. The experimental setup consisted of having an instrument project uniform disks on the fundus and recording their retinal images after a double pass through the eye. Additionally, the relative spectral sensitivity for the same wavelengths was measured using heterochromatic flicker photometry for a stimulus of a 0.4° radius with and without the presence of a synchronously flickering concentric annulus. We concluded that although light backscattered from the fundus contributes to vision, the effect is not strong and can only be observed under appropriate laboratory conditions. This suggests that diffuse light from deeper fundus layers is unlikely to have a practical relevance to vision.

Differentiation of visual spectra and nuptial colorations of two Paratanakia himantegus subspecies (Cyprinoidea: Acheilognathidae) in response to the distinct photic conditions of their habitats.

Vision, an important sensory modality of many animals, exhibits plasticity in that it adapts to environmental conditions to maintain its sensory efficiency. Nuptial coloration is used to attract mates and hence should be tightly coupled to vision. In Taiwan, two closely related bitterlings (Paratanakia himantegus himantegus and Paratanakia himantegus chii) with different male nuptial colorations reside in different habitats. We compared the visual spectral sensitivities of these subspecies with the ambient light spectra of their habitats to determine whether their visual abilities correspond with photic parameters and correlate with nuptial colorations. Theelectroretinogram (ERG) results revealed that the relative spectral sensitivity of P.h. himantegus was higher at 670 nm, but lower at 370 nm, than the sensitivity of P. h. chii. Both bitterlings could perceive and reflect UV light, but the UV reflection patterns differed between genders. Furthermore, the relative irradiance intensity of the light spectra in the habitat of P. h. himantegus was higher at long wavelengths (480-700 nm), but lower at short wavelengths (350-450 nm), than the light spectra in the habitats of P. h.chii. Two phylogenetically closely related bitterlings, P. h. himantegus and P. h. chii, dwell in different waters and exhibit different nuptial colorations and spectral sensitivities, which may be the results of speciation by sensory drive. Sensory ability and signal diversity accommodating photic environment may promote diversity of bitterling fishes. UV light was demonstrated to be a possible component of bitterling visual communication. The UV cue may assist bitterlings in genderidentification.

Radiometric calibration of optical microscopy and microspectroscopy apparata over a broad spectral range using a special thin-film luminescence standard

Application capabilities of optical microscopes and microspectroscopes can be considerably enhanced by a proper calibration of their spectral sensitivity. We propose and demonstrate a method of relative and absolute calibration of a microspectroscope over an extraordinary broad spectral range covered by two (parallel) detection branches in visible and near-infrared spectral regions. The key point of the absolute calibration of a relative spectral sensitivity is application of the standard sample formed by a thin layer of Si nanocrystals with stable and efficient photoluminescence. The spectral PL quantum yield and the PL spatial distribution of the standard sample must be characterized by separate experiments. The absolutely calibrated microspectroscope enables to characterize spectral photon emittance of a studied object or even its luminescence quantum yield (QY) if additional knowledge about spatial distribution of emission and about excitance is available. Capabilities of the calibrated microspectroscope are demonstrated by measuring external QY of electroluminescence from a standard poly-Si solar-cell and of photoluminescence of Er-doped Si nanocrystals.

Androgens increase lws opsin expression and red sensitivity in male three-spined sticklebacks.

Optomotor studies have shown that three-spined sticklebacks (Gasterosteus aculeatus) are more sensitive to red during summer than winter, which may be related to the need to detect the red breeding colour of males. This study aimed to determine whether this change of red light sensitivity is specifically related to reproductive physiology. The mRNA levels of opsin genes were examined in the retinae of sexually mature and immature fish, as well as in sham-operated males, castrated control males, or castrated males implanted with androgen 11-ketoandrostenedione (11 KA), maintained under stimulatory (L16:D8) or inhibitory (L8:D16) photoperiods. In both sexes, red-sensitive opsin gene (lws) mRNA levels were higher in sexually mature than in immature fish. Under L16:D8, lws mRNA levels were higher in intact than in castrated males, and were up-regulated by 11 KA treatment in castrated males. Moreover, electroretinogram data confirmed that sexual maturation resulted in higher relative red spectral sensitivity. Mature males under L16:D8 were more sensitive to red light than males under L8:D16. Red light sensitivity under L16:D8 was diminished by castration, but increased by 11 KA treatment. Thus, in sexually mature male sticklebacks, androgen is a key factor in enhancing sensitivity to red light via regulation of opsin gene expression. This is the first study to demonstrate that sex hormones can regulate spectral vision sensitivity.

Determination of calcium in wine using reconfigurable PSoC based spectrophotometer

This paper discusses the determination of calcium in wine samples using Programmable Systemon-Chip (PSoC) microcontroller. This embedded system uses a PSoC CY8C27443 integrated circuit (IC) spectrophotometer as core unit, high intensity orange LED as light source and photodiode as light detector having the relative spectral sensitivity above 93% in the range of 550–650 nm. This single-chip design reduces hardware complexity and increases the stability by miniaturizing the device. The instrument obeys Beer’s law up to the concentration of 160 mg/L. Coloring agent Methylthymol Blue (MTB) forms a complex with calcium in presence of alkali (pH ≈ 12); the complex exhibits maximum absorbance at 610 nm. The spectral range, concentration of MTB and pH of the solution at which the reaction is carried out are optimized. The results of the developed method are compared statistically with those obtained by a conventional method by applying Student’s t-test and F-test. The regression analysis reveals excellent correlation (R2 = 0.9998) and regression line equation obtained for that line Y = 0.29 + 0.99X with standard error of 0.62. It can be concluded that the obtained results are in good agreement with the reference method at 95% confidence level.

Artificial neural nets in color measurements

An integral colorimeter that functions according to the principles of artificial neural nets is proposed. Methods of increasing the precision of reproduction of the relative spectral sensitivity of the colorimeter’s measurement channels, which must correspond to the color addition function of a standard observer in the course of production, are considered.

Transmission-Type Ionization Chamber for Monitoring Dose Power of an X-Ray Therapeutic Apparatus

A transmission-type ionization chamber for monitoring dose power of the Roentgen-TA 150/10 X-ray therapeutic apparatus is described. The X-ray working dose range of the apparatus is 4.5-70 keV. The X-ray chamber sensitivity at Al equivalent 100 nm for X-ray energy 4.5 keV is 2·10–11 A/mGy/sec. Relative spectral sensitivity error of the chamber within the given range is ±13.0 %. The correction of the apparatus reduces this error to ±3.0 %.

Monochromatic radiation source for calibration of the relative spectral sensitivity of earth observation instruments

The design of the major components and parts of a wide-aperture monochromatic radiation source for calibration of earth observation instruments, and its technical and metrological characteristics, are discussed. The uncertainty budget for reproducing the relative spectral distribution of the source at wavelengths of 0.3–2.5 μm is calculated.